mirror of
https://github.com/torvalds/linux.git
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9187210eee
Core & protocols ---------------- - Large effort by Eric to lower rtnl_lock pressure and remove locks: - Make commonly used parts of rtnetlink (address, route dumps etc.) lockless, protected by RCU instead of rtnl_lock. - Add a netns exit callback which already holds rtnl_lock, allowing netns exit to take rtnl_lock once in the core instead of once for each driver / callback. - Remove locks / serialization in the socket diag interface. - Remove 6 calls to synchronize_rcu() while holding rtnl_lock. - Remove the dev_base_lock, depend on RCU where necessary. - Support busy polling on a per-epoll context basis. Poll length and budget parameters can be set independently of system defaults. - Introduce struct net_hotdata, to make sure read-mostly global config variables fit in as few cache lines as possible. - Add optional per-nexthop statistics to ease monitoring / debug of ECMP imbalance problems. - Support TCP_NOTSENT_LOWAT in MPTCP. - Ensure that IPv6 temporary addresses' preferred lifetimes are long enough, compared to other configured lifetimes, and at least 2 sec. - Support forwarding of ICMP Error messages in IPSec, per RFC 4301. - Add support for the independent control state machine for bonding per IEEE 802.1AX-2008 5.4.15 in addition to the existing coupled control state machine. - Add "network ID" to MCTP socket APIs to support hosts with multiple disjoint MCTP networks. - Re-use the mono_delivery_time skbuff bit for packets which user space wants to be sent at a specified time. Maintain the timing information while traversing veth links, bridge etc. - Take advantage of MSG_SPLICE_PAGES for RxRPC DATA and ACK packets. - Simplify many places iterating over netdevs by using an xarray instead of a hash table walk (hash table remains in place, for use on fastpaths). - Speed up scanning for expired routes by keeping a dedicated list. - Speed up "generic" XDP by trying harder to avoid large allocations. - Support attaching arbitrary metadata to netconsole messages. Things we sprinkled into general kernel code -------------------------------------------- - Enforce VM_IOREMAP flag and range in ioremap_page_range and introduce VM_SPARSE kind and vm_area_[un]map_pages (used by bpf_arena). - Rework selftest harness to enable the use of the full range of ksft exit code (pass, fail, skip, xfail, xpass). Netfilter --------- - Allow userspace to define a table that is exclusively owned by a daemon (via netlink socket aliveness) without auto-removing this table when the userspace program exits. Such table gets marked as orphaned and a restarting management daemon can re-attach/regain ownership. - Speed up element insertions to nftables' concatenated-ranges set type. Compact a few related data structures. BPF --- - Add BPF token support for delegating a subset of BPF subsystem functionality from privileged system-wide daemons such as systemd through special mount options for userns-bound BPF fs to a trusted & unprivileged application. - Introduce bpf_arena which is sparse shared memory region between BPF program and user space where structures inside the arena can have pointers to other areas of the arena, and pointers work seamlessly for both user-space programs and BPF programs. - Introduce may_goto instruction that is a contract between the verifier and the program. The verifier allows the program to loop assuming it's behaving well, but reserves the right to terminate it. - Extend the BPF verifier to enable static subprog calls in spin lock critical sections. - Support registration of struct_ops types from modules which helps projects like fuse-bpf that seeks to implement a new struct_ops type. - Add support for retrieval of cookies for perf/kprobe multi links. - Support arbitrary TCP SYN cookie generation / validation in the TC layer with BPF to allow creating SYN flood handling in BPF firewalls. - Add code generation to inline the bpf_kptr_xchg() helper which improves performance when stashing/popping the allocated BPF objects. Wireless -------- - Add SPP (signaling and payload protected) AMSDU support. - Support wider bandwidth OFDMA, as required for EHT operation. Driver API ---------- - Major overhaul of the Energy Efficient Ethernet internals to support new link modes (2.5GE, 5GE), share more code between drivers (especially those using phylib), and encourage more uniform behavior. Convert and clean up drivers. - Define an API for querying per netdev queue statistics from drivers. - IPSec: account in global stats for fully offloaded sessions. - Create a concept of Ethernet PHY Packages at the Device Tree level, to allow parameterizing the existing PHY package code. - Enable Rx hashing (RSS) on GTP protocol fields. Misc ---- - Improvements and refactoring all over networking selftests. - Create uniform module aliases for TC classifiers, actions, and packet schedulers to simplify creating modprobe policies. - Address all missing MODULE_DESCRIPTION() warnings in networking. - Extend the Netlink descriptions in YAML to cover message encapsulation or "Netlink polymorphism", where interpretation of nested attributes depends on link type, classifier type or some other "class type". Drivers ------- - Ethernet high-speed NICs: - Add a new driver for Marvell's Octeon PCI Endpoint NIC VF. - Intel (100G, ice, idpf): - support E825-C devices - nVidia/Mellanox: - support devices with one port and multiple PCIe links - Broadcom (bnxt): - support n-tuple filters - support configuring the RSS key - Wangxun (ngbe/txgbe): - implement irq_domain for TXGBE's sub-interrupts - Pensando/AMD: - support XDP - optimize queue submission and wakeup handling (+17% bps) - optimize struct layout, saving 28% of memory on queues - Ethernet NICs embedded and virtual: - Google cloud vNIC: - refactor driver to perform memory allocations for new queue config before stopping and freeing the old queue memory - Synopsys (stmmac): - obey queueMaxSDU and implement counters required by 802.1Qbv - Renesas (ravb): - support packet checksum offload - suspend to RAM and runtime PM support - Ethernet switches: - nVidia/Mellanox: - support for nexthop group statistics - Microchip: - ksz8: implement PHY loopback - add support for KSZ8567, a 7-port 10/100Mbps switch - PTP: - New driver for RENESAS FemtoClock3 Wireless clock generator. - Support OCP PTP cards designed and built by Adva. - CAN: - Support recvmsg() flags for own, local and remote traffic on CAN BCM sockets. - Support for esd GmbH PCIe/402 CAN device family. - m_can: - Rx/Tx submission coalescing - wake on frame Rx - WiFi: - Intel (iwlwifi): - enable signaling and payload protected A-MSDUs - support wider-bandwidth OFDMA - support for new devices - bump FW API to 89 for AX devices; 90 for BZ/SC devices - MediaTek (mt76): - mt7915: newer ADIE version support - mt7925: radio temperature sensor support - Qualcomm (ath11k): - support 6 GHz station power modes: Low Power Indoor (LPI), Standard Power) SP and Very Low Power (VLP) - QCA6390 & WCN6855: support 2 concurrent station interfaces - QCA2066 support - Qualcomm (ath12k): - refactoring in preparation for Multi-Link Operation (MLO) support - 1024 Block Ack window size support - firmware-2.bin support - support having multiple identical PCI devices (firmware needs to have ATH12K_FW_FEATURE_MULTI_QRTR_ID) - QCN9274: support split-PHY devices - WCN7850: enable Power Save Mode in station mode - WCN7850: P2P support - RealTek: - rtw88: support for more rtw8811cu and rtw8821cu devices - rtw89: support SCAN_RANDOM_SN and SET_SCAN_DWELL - rtlwifi: speed up USB firmware initialization - rtwl8xxxu: - RTL8188F: concurrent interface support - Channel Switch Announcement (CSA) support in AP mode - Broadcom (brcmfmac): - per-vendor feature support - per-vendor SAE password setup - DMI nvram filename quirk for ACEPC W5 Pro Signed-off-by: Jakub Kicinski <kuba@kernel.org> -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEE6jPA+I1ugmIBA4hXMUZtbf5SIrsFAmXv0mgACgkQMUZtbf5S IrtgMxAAuRd+WJW++SENr4KxIWhYO1q6Xcxnai43wrNkan9swD24icG8TYALt4f3 yoT6idQvWReAb5JNlh9rUQz8R7E0nJXlvEFn5MtJwcthx2C6wFo/XkJlddlRrT+j c2xGILwLjRhW65LaC0MZ2ECbEERkFz8xcGfK2SWzUgh6KYvPjcRfKFxugpM7xOQK P/Wnqhs4fVRS/Mj/bCcXcO+yhwC121Q3qVeQVjGS0AzEC65hAW87a/kc2BfgcegD EyI9R7mf6criQwX+0awubjfoIdr4oW/8oDVNvUDczkJkbaEVaLMQk9P5x/0XnnVS UHUchWXyI80Q8Rj12uN1/I0h3WtwNQnCRBuLSmtm6GLfCAwbLvp2nGWDnaXiqryW DVKUIHGvqPKjkOOMOVfSvfB3LvkS3xsFVVYiQBQCn0YSs/gtu4CoF2Nty9CiLPbK tTuxUnLdPDZDxU//l0VArZmP8p2JM7XQGJ+JH8GFH4SBTyBR23e0iyPSoyaxjnYn RReDnHMVsrS1i7GPhbqDJWn+uqMSs7N149i0XmmyeqwQHUVSJN3J2BApP2nCaDfy H2lTuYly5FfEezt61NvCE4qr/VsWeEjm1fYlFQ9dFn4pGn+HghyCpw+xD1ZN56DN lujemau5B3kk1UTtAT4ypPqvuqjkRFqpNV2LzsJSk/Js+hApw8Y= =oY52 -----END PGP SIGNATURE----- Merge tag 'net-next-6.9' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next Pull networking updates from Jakub Kicinski: "Core & protocols: - Large effort by Eric to lower rtnl_lock pressure and remove locks: - Make commonly used parts of rtnetlink (address, route dumps etc) lockless, protected by RCU instead of rtnl_lock. - Add a netns exit callback which already holds rtnl_lock, allowing netns exit to take rtnl_lock once in the core instead of once for each driver / callback. - Remove locks / serialization in the socket diag interface. - Remove 6 calls to synchronize_rcu() while holding rtnl_lock. - Remove the dev_base_lock, depend on RCU where necessary. - Support busy polling on a per-epoll context basis. Poll length and budget parameters can be set independently of system defaults. - Introduce struct net_hotdata, to make sure read-mostly global config variables fit in as few cache lines as possible. - Add optional per-nexthop statistics to ease monitoring / debug of ECMP imbalance problems. - Support TCP_NOTSENT_LOWAT in MPTCP. - Ensure that IPv6 temporary addresses' preferred lifetimes are long enough, compared to other configured lifetimes, and at least 2 sec. - Support forwarding of ICMP Error messages in IPSec, per RFC 4301. - Add support for the independent control state machine for bonding per IEEE 802.1AX-2008 5.4.15 in addition to the existing coupled control state machine. - Add "network ID" to MCTP socket APIs to support hosts with multiple disjoint MCTP networks. - Re-use the mono_delivery_time skbuff bit for packets which user space wants to be sent at a specified time. Maintain the timing information while traversing veth links, bridge etc. - Take advantage of MSG_SPLICE_PAGES for RxRPC DATA and ACK packets. - Simplify many places iterating over netdevs by using an xarray instead of a hash table walk (hash table remains in place, for use on fastpaths). - Speed up scanning for expired routes by keeping a dedicated list. - Speed up "generic" XDP by trying harder to avoid large allocations. - Support attaching arbitrary metadata to netconsole messages. Things we sprinkled into general kernel code: - Enforce VM_IOREMAP flag and range in ioremap_page_range and introduce VM_SPARSE kind and vm_area_[un]map_pages (used by bpf_arena). - Rework selftest harness to enable the use of the full range of ksft exit code (pass, fail, skip, xfail, xpass). Netfilter: - Allow userspace to define a table that is exclusively owned by a daemon (via netlink socket aliveness) without auto-removing this table when the userspace program exits. Such table gets marked as orphaned and a restarting management daemon can re-attach/regain ownership. - Speed up element insertions to nftables' concatenated-ranges set type. Compact a few related data structures. BPF: - Add BPF token support for delegating a subset of BPF subsystem functionality from privileged system-wide daemons such as systemd through special mount options for userns-bound BPF fs to a trusted & unprivileged application. - Introduce bpf_arena which is sparse shared memory region between BPF program and user space where structures inside the arena can have pointers to other areas of the arena, and pointers work seamlessly for both user-space programs and BPF programs. - Introduce may_goto instruction that is a contract between the verifier and the program. The verifier allows the program to loop assuming it's behaving well, but reserves the right to terminate it. - Extend the BPF verifier to enable static subprog calls in spin lock critical sections. - Support registration of struct_ops types from modules which helps projects like fuse-bpf that seeks to implement a new struct_ops type. - Add support for retrieval of cookies for perf/kprobe multi links. - Support arbitrary TCP SYN cookie generation / validation in the TC layer with BPF to allow creating SYN flood handling in BPF firewalls. - Add code generation to inline the bpf_kptr_xchg() helper which improves performance when stashing/popping the allocated BPF objects. Wireless: - Add SPP (signaling and payload protected) AMSDU support. - Support wider bandwidth OFDMA, as required for EHT operation. Driver API: - Major overhaul of the Energy Efficient Ethernet internals to support new link modes (2.5GE, 5GE), share more code between drivers (especially those using phylib), and encourage more uniform behavior. Convert and clean up drivers. - Define an API for querying per netdev queue statistics from drivers. - IPSec: account in global stats for fully offloaded sessions. - Create a concept of Ethernet PHY Packages at the Device Tree level, to allow parameterizing the existing PHY package code. - Enable Rx hashing (RSS) on GTP protocol fields. Misc: - Improvements and refactoring all over networking selftests. - Create uniform module aliases for TC classifiers, actions, and packet schedulers to simplify creating modprobe policies. - Address all missing MODULE_DESCRIPTION() warnings in networking. - Extend the Netlink descriptions in YAML to cover message encapsulation or "Netlink polymorphism", where interpretation of nested attributes depends on link type, classifier type or some other "class type". Drivers: - Ethernet high-speed NICs: - Add a new driver for Marvell's Octeon PCI Endpoint NIC VF. - Intel (100G, ice, idpf): - support E825-C devices - nVidia/Mellanox: - support devices with one port and multiple PCIe links - Broadcom (bnxt): - support n-tuple filters - support configuring the RSS key - Wangxun (ngbe/txgbe): - implement irq_domain for TXGBE's sub-interrupts - Pensando/AMD: - support XDP - optimize queue submission and wakeup handling (+17% bps) - optimize struct layout, saving 28% of memory on queues - Ethernet NICs embedded and virtual: - Google cloud vNIC: - refactor driver to perform memory allocations for new queue config before stopping and freeing the old queue memory - Synopsys (stmmac): - obey queueMaxSDU and implement counters required by 802.1Qbv - Renesas (ravb): - support packet checksum offload - suspend to RAM and runtime PM support - Ethernet switches: - nVidia/Mellanox: - support for nexthop group statistics - Microchip: - ksz8: implement PHY loopback - add support for KSZ8567, a 7-port 10/100Mbps switch - PTP: - New driver for RENESAS FemtoClock3 Wireless clock generator. - Support OCP PTP cards designed and built by Adva. - CAN: - Support recvmsg() flags for own, local and remote traffic on CAN BCM sockets. - Support for esd GmbH PCIe/402 CAN device family. - m_can: - Rx/Tx submission coalescing - wake on frame Rx - WiFi: - Intel (iwlwifi): - enable signaling and payload protected A-MSDUs - support wider-bandwidth OFDMA - support for new devices - bump FW API to 89 for AX devices; 90 for BZ/SC devices - MediaTek (mt76): - mt7915: newer ADIE version support - mt7925: radio temperature sensor support - Qualcomm (ath11k): - support 6 GHz station power modes: Low Power Indoor (LPI), Standard Power) SP and Very Low Power (VLP) - QCA6390 & WCN6855: support 2 concurrent station interfaces - QCA2066 support - Qualcomm (ath12k): - refactoring in preparation for Multi-Link Operation (MLO) support - 1024 Block Ack window size support - firmware-2.bin support - support having multiple identical PCI devices (firmware needs to have ATH12K_FW_FEATURE_MULTI_QRTR_ID) - QCN9274: support split-PHY devices - WCN7850: enable Power Save Mode in station mode - WCN7850: P2P support - RealTek: - rtw88: support for more rtw8811cu and rtw8821cu devices - rtw89: support SCAN_RANDOM_SN and SET_SCAN_DWELL - rtlwifi: speed up USB firmware initialization - rtwl8xxxu: - RTL8188F: concurrent interface support - Channel Switch Announcement (CSA) support in AP mode - Broadcom (brcmfmac): - per-vendor feature support - per-vendor SAE password setup - DMI nvram filename quirk for ACEPC W5 Pro" * tag 'net-next-6.9' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (2255 commits) nexthop: Fix splat with CONFIG_DEBUG_PREEMPT=y nexthop: Fix out-of-bounds access during attribute validation nexthop: Only parse NHA_OP_FLAGS for dump messages that require it nexthop: Only parse NHA_OP_FLAGS for get messages that require it bpf: move sleepable flag from bpf_prog_aux to bpf_prog bpf: hardcode BPF_PROG_PACK_SIZE to 2MB * num_possible_nodes() selftests/bpf: Add kprobe multi triggering benchmarks ptp: Move from simple ida to xarray vxlan: Remove generic .ndo_get_stats64 vxlan: Do not alloc tstats manually devlink: Add comments to use netlink gen tool nfp: flower: handle acti_netdevs allocation failure net/packet: Add getsockopt support for PACKET_COPY_THRESH net/netlink: Add getsockopt support for NETLINK_LISTEN_ALL_NSID selftests/bpf: Add bpf_arena_htab test. selftests/bpf: Add bpf_arena_list test. selftests/bpf: Add unit tests for bpf_arena_alloc/free_pages bpf: Add helper macro bpf_addr_space_cast() libbpf: Recognize __arena global variables. bpftool: Recognize arena map type ...
2590 lines
69 KiB
C
2590 lines
69 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* fs/eventpoll.c (Efficient event retrieval implementation)
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* Copyright (C) 2001,...,2009 Davide Libenzi
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*
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* Davide Libenzi <davidel@xmailserver.org>
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*/
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/sched/signal.h>
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#include <linux/fs.h>
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#include <linux/file.h>
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#include <linux/signal.h>
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#include <linux/errno.h>
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/poll.h>
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#include <linux/string.h>
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#include <linux/list.h>
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#include <linux/hash.h>
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#include <linux/spinlock.h>
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#include <linux/syscalls.h>
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#include <linux/rbtree.h>
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#include <linux/wait.h>
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#include <linux/eventpoll.h>
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#include <linux/mount.h>
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#include <linux/bitops.h>
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#include <linux/mutex.h>
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#include <linux/anon_inodes.h>
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#include <linux/device.h>
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#include <linux/uaccess.h>
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#include <asm/io.h>
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#include <asm/mman.h>
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#include <linux/atomic.h>
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#include <linux/proc_fs.h>
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#include <linux/seq_file.h>
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#include <linux/compat.h>
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#include <linux/rculist.h>
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#include <linux/capability.h>
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#include <net/busy_poll.h>
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/*
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* LOCKING:
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* There are three level of locking required by epoll :
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*
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* 1) epnested_mutex (mutex)
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* 2) ep->mtx (mutex)
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* 3) ep->lock (rwlock)
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*
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* The acquire order is the one listed above, from 1 to 3.
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* We need a rwlock (ep->lock) because we manipulate objects
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* from inside the poll callback, that might be triggered from
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* a wake_up() that in turn might be called from IRQ context.
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* So we can't sleep inside the poll callback and hence we need
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* a spinlock. During the event transfer loop (from kernel to
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* user space) we could end up sleeping due a copy_to_user(), so
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* we need a lock that will allow us to sleep. This lock is a
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* mutex (ep->mtx). It is acquired during the event transfer loop,
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* during epoll_ctl(EPOLL_CTL_DEL) and during eventpoll_release_file().
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* The epnested_mutex is acquired when inserting an epoll fd onto another
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* epoll fd. We do this so that we walk the epoll tree and ensure that this
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* insertion does not create a cycle of epoll file descriptors, which
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* could lead to deadlock. We need a global mutex to prevent two
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* simultaneous inserts (A into B and B into A) from racing and
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* constructing a cycle without either insert observing that it is
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* going to.
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* It is necessary to acquire multiple "ep->mtx"es at once in the
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* case when one epoll fd is added to another. In this case, we
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* always acquire the locks in the order of nesting (i.e. after
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* epoll_ctl(e1, EPOLL_CTL_ADD, e2), e1->mtx will always be acquired
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* before e2->mtx). Since we disallow cycles of epoll file
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* descriptors, this ensures that the mutexes are well-ordered. In
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* order to communicate this nesting to lockdep, when walking a tree
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* of epoll file descriptors, we use the current recursion depth as
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* the lockdep subkey.
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* It is possible to drop the "ep->mtx" and to use the global
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* mutex "epnested_mutex" (together with "ep->lock") to have it working,
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* but having "ep->mtx" will make the interface more scalable.
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* Events that require holding "epnested_mutex" are very rare, while for
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* normal operations the epoll private "ep->mtx" will guarantee
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* a better scalability.
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*/
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/* Epoll private bits inside the event mask */
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#define EP_PRIVATE_BITS (EPOLLWAKEUP | EPOLLONESHOT | EPOLLET | EPOLLEXCLUSIVE)
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#define EPOLLINOUT_BITS (EPOLLIN | EPOLLOUT)
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#define EPOLLEXCLUSIVE_OK_BITS (EPOLLINOUT_BITS | EPOLLERR | EPOLLHUP | \
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EPOLLWAKEUP | EPOLLET | EPOLLEXCLUSIVE)
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/* Maximum number of nesting allowed inside epoll sets */
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#define EP_MAX_NESTS 4
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#define EP_MAX_EVENTS (INT_MAX / sizeof(struct epoll_event))
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#define EP_UNACTIVE_PTR ((void *) -1L)
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#define EP_ITEM_COST (sizeof(struct epitem) + sizeof(struct eppoll_entry))
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struct epoll_filefd {
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struct file *file;
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int fd;
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} __packed;
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/* Wait structure used by the poll hooks */
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struct eppoll_entry {
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/* List header used to link this structure to the "struct epitem" */
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struct eppoll_entry *next;
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/* The "base" pointer is set to the container "struct epitem" */
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struct epitem *base;
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/*
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* Wait queue item that will be linked to the target file wait
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* queue head.
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*/
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wait_queue_entry_t wait;
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/* The wait queue head that linked the "wait" wait queue item */
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wait_queue_head_t *whead;
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};
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/*
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* Each file descriptor added to the eventpoll interface will
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* have an entry of this type linked to the "rbr" RB tree.
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* Avoid increasing the size of this struct, there can be many thousands
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* of these on a server and we do not want this to take another cache line.
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*/
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struct epitem {
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union {
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/* RB tree node links this structure to the eventpoll RB tree */
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struct rb_node rbn;
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/* Used to free the struct epitem */
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struct rcu_head rcu;
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};
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/* List header used to link this structure to the eventpoll ready list */
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struct list_head rdllink;
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/*
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* Works together "struct eventpoll"->ovflist in keeping the
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* single linked chain of items.
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*/
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struct epitem *next;
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/* The file descriptor information this item refers to */
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struct epoll_filefd ffd;
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/*
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* Protected by file->f_lock, true for to-be-released epitem already
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* removed from the "struct file" items list; together with
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* eventpoll->refcount orchestrates "struct eventpoll" disposal
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*/
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bool dying;
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/* List containing poll wait queues */
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struct eppoll_entry *pwqlist;
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/* The "container" of this item */
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struct eventpoll *ep;
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/* List header used to link this item to the "struct file" items list */
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struct hlist_node fllink;
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/* wakeup_source used when EPOLLWAKEUP is set */
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struct wakeup_source __rcu *ws;
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/* The structure that describe the interested events and the source fd */
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struct epoll_event event;
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};
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/*
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* This structure is stored inside the "private_data" member of the file
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* structure and represents the main data structure for the eventpoll
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* interface.
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*/
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struct eventpoll {
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/*
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* This mutex is used to ensure that files are not removed
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* while epoll is using them. This is held during the event
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* collection loop, the file cleanup path, the epoll file exit
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* code and the ctl operations.
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*/
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struct mutex mtx;
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/* Wait queue used by sys_epoll_wait() */
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wait_queue_head_t wq;
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/* Wait queue used by file->poll() */
|
|
wait_queue_head_t poll_wait;
|
|
|
|
/* List of ready file descriptors */
|
|
struct list_head rdllist;
|
|
|
|
/* Lock which protects rdllist and ovflist */
|
|
rwlock_t lock;
|
|
|
|
/* RB tree root used to store monitored fd structs */
|
|
struct rb_root_cached rbr;
|
|
|
|
/*
|
|
* This is a single linked list that chains all the "struct epitem" that
|
|
* happened while transferring ready events to userspace w/out
|
|
* holding ->lock.
|
|
*/
|
|
struct epitem *ovflist;
|
|
|
|
/* wakeup_source used when ep_send_events or __ep_eventpoll_poll is running */
|
|
struct wakeup_source *ws;
|
|
|
|
/* The user that created the eventpoll descriptor */
|
|
struct user_struct *user;
|
|
|
|
struct file *file;
|
|
|
|
/* used to optimize loop detection check */
|
|
u64 gen;
|
|
struct hlist_head refs;
|
|
|
|
/*
|
|
* usage count, used together with epitem->dying to
|
|
* orchestrate the disposal of this struct
|
|
*/
|
|
refcount_t refcount;
|
|
|
|
#ifdef CONFIG_NET_RX_BUSY_POLL
|
|
/* used to track busy poll napi_id */
|
|
unsigned int napi_id;
|
|
/* busy poll timeout */
|
|
u32 busy_poll_usecs;
|
|
/* busy poll packet budget */
|
|
u16 busy_poll_budget;
|
|
bool prefer_busy_poll;
|
|
#endif
|
|
|
|
#ifdef CONFIG_DEBUG_LOCK_ALLOC
|
|
/* tracks wakeup nests for lockdep validation */
|
|
u8 nests;
|
|
#endif
|
|
};
|
|
|
|
/* Wrapper struct used by poll queueing */
|
|
struct ep_pqueue {
|
|
poll_table pt;
|
|
struct epitem *epi;
|
|
};
|
|
|
|
/*
|
|
* Configuration options available inside /proc/sys/fs/epoll/
|
|
*/
|
|
/* Maximum number of epoll watched descriptors, per user */
|
|
static long max_user_watches __read_mostly;
|
|
|
|
/* Used for cycles detection */
|
|
static DEFINE_MUTEX(epnested_mutex);
|
|
|
|
static u64 loop_check_gen = 0;
|
|
|
|
/* Used to check for epoll file descriptor inclusion loops */
|
|
static struct eventpoll *inserting_into;
|
|
|
|
/* Slab cache used to allocate "struct epitem" */
|
|
static struct kmem_cache *epi_cache __ro_after_init;
|
|
|
|
/* Slab cache used to allocate "struct eppoll_entry" */
|
|
static struct kmem_cache *pwq_cache __ro_after_init;
|
|
|
|
/*
|
|
* List of files with newly added links, where we may need to limit the number
|
|
* of emanating paths. Protected by the epnested_mutex.
|
|
*/
|
|
struct epitems_head {
|
|
struct hlist_head epitems;
|
|
struct epitems_head *next;
|
|
};
|
|
static struct epitems_head *tfile_check_list = EP_UNACTIVE_PTR;
|
|
|
|
static struct kmem_cache *ephead_cache __ro_after_init;
|
|
|
|
static inline void free_ephead(struct epitems_head *head)
|
|
{
|
|
if (head)
|
|
kmem_cache_free(ephead_cache, head);
|
|
}
|
|
|
|
static void list_file(struct file *file)
|
|
{
|
|
struct epitems_head *head;
|
|
|
|
head = container_of(file->f_ep, struct epitems_head, epitems);
|
|
if (!head->next) {
|
|
head->next = tfile_check_list;
|
|
tfile_check_list = head;
|
|
}
|
|
}
|
|
|
|
static void unlist_file(struct epitems_head *head)
|
|
{
|
|
struct epitems_head *to_free = head;
|
|
struct hlist_node *p = rcu_dereference(hlist_first_rcu(&head->epitems));
|
|
if (p) {
|
|
struct epitem *epi= container_of(p, struct epitem, fllink);
|
|
spin_lock(&epi->ffd.file->f_lock);
|
|
if (!hlist_empty(&head->epitems))
|
|
to_free = NULL;
|
|
head->next = NULL;
|
|
spin_unlock(&epi->ffd.file->f_lock);
|
|
}
|
|
free_ephead(to_free);
|
|
}
|
|
|
|
#ifdef CONFIG_SYSCTL
|
|
|
|
#include <linux/sysctl.h>
|
|
|
|
static long long_zero;
|
|
static long long_max = LONG_MAX;
|
|
|
|
static struct ctl_table epoll_table[] = {
|
|
{
|
|
.procname = "max_user_watches",
|
|
.data = &max_user_watches,
|
|
.maxlen = sizeof(max_user_watches),
|
|
.mode = 0644,
|
|
.proc_handler = proc_doulongvec_minmax,
|
|
.extra1 = &long_zero,
|
|
.extra2 = &long_max,
|
|
},
|
|
};
|
|
|
|
static void __init epoll_sysctls_init(void)
|
|
{
|
|
register_sysctl("fs/epoll", epoll_table);
|
|
}
|
|
#else
|
|
#define epoll_sysctls_init() do { } while (0)
|
|
#endif /* CONFIG_SYSCTL */
|
|
|
|
static const struct file_operations eventpoll_fops;
|
|
|
|
static inline int is_file_epoll(struct file *f)
|
|
{
|
|
return f->f_op == &eventpoll_fops;
|
|
}
|
|
|
|
/* Setup the structure that is used as key for the RB tree */
|
|
static inline void ep_set_ffd(struct epoll_filefd *ffd,
|
|
struct file *file, int fd)
|
|
{
|
|
ffd->file = file;
|
|
ffd->fd = fd;
|
|
}
|
|
|
|
/* Compare RB tree keys */
|
|
static inline int ep_cmp_ffd(struct epoll_filefd *p1,
|
|
struct epoll_filefd *p2)
|
|
{
|
|
return (p1->file > p2->file ? +1:
|
|
(p1->file < p2->file ? -1 : p1->fd - p2->fd));
|
|
}
|
|
|
|
/* Tells us if the item is currently linked */
|
|
static inline int ep_is_linked(struct epitem *epi)
|
|
{
|
|
return !list_empty(&epi->rdllink);
|
|
}
|
|
|
|
static inline struct eppoll_entry *ep_pwq_from_wait(wait_queue_entry_t *p)
|
|
{
|
|
return container_of(p, struct eppoll_entry, wait);
|
|
}
|
|
|
|
/* Get the "struct epitem" from a wait queue pointer */
|
|
static inline struct epitem *ep_item_from_wait(wait_queue_entry_t *p)
|
|
{
|
|
return container_of(p, struct eppoll_entry, wait)->base;
|
|
}
|
|
|
|
/**
|
|
* ep_events_available - Checks if ready events might be available.
|
|
*
|
|
* @ep: Pointer to the eventpoll context.
|
|
*
|
|
* Return: a value different than %zero if ready events are available,
|
|
* or %zero otherwise.
|
|
*/
|
|
static inline int ep_events_available(struct eventpoll *ep)
|
|
{
|
|
return !list_empty_careful(&ep->rdllist) ||
|
|
READ_ONCE(ep->ovflist) != EP_UNACTIVE_PTR;
|
|
}
|
|
|
|
#ifdef CONFIG_NET_RX_BUSY_POLL
|
|
/**
|
|
* busy_loop_ep_timeout - check if busy poll has timed out. The timeout value
|
|
* from the epoll instance ep is preferred, but if it is not set fallback to
|
|
* the system-wide global via busy_loop_timeout.
|
|
*
|
|
* @start_time: The start time used to compute the remaining time until timeout.
|
|
* @ep: Pointer to the eventpoll context.
|
|
*
|
|
* Return: true if the timeout has expired, false otherwise.
|
|
*/
|
|
static bool busy_loop_ep_timeout(unsigned long start_time,
|
|
struct eventpoll *ep)
|
|
{
|
|
unsigned long bp_usec = READ_ONCE(ep->busy_poll_usecs);
|
|
|
|
if (bp_usec) {
|
|
unsigned long end_time = start_time + bp_usec;
|
|
unsigned long now = busy_loop_current_time();
|
|
|
|
return time_after(now, end_time);
|
|
} else {
|
|
return busy_loop_timeout(start_time);
|
|
}
|
|
}
|
|
|
|
static bool ep_busy_loop_on(struct eventpoll *ep)
|
|
{
|
|
return !!ep->busy_poll_usecs || net_busy_loop_on();
|
|
}
|
|
|
|
static bool ep_busy_loop_end(void *p, unsigned long start_time)
|
|
{
|
|
struct eventpoll *ep = p;
|
|
|
|
return ep_events_available(ep) || busy_loop_ep_timeout(start_time, ep);
|
|
}
|
|
|
|
/*
|
|
* Busy poll if globally on and supporting sockets found && no events,
|
|
* busy loop will return if need_resched or ep_events_available.
|
|
*
|
|
* we must do our busy polling with irqs enabled
|
|
*/
|
|
static bool ep_busy_loop(struct eventpoll *ep, int nonblock)
|
|
{
|
|
unsigned int napi_id = READ_ONCE(ep->napi_id);
|
|
u16 budget = READ_ONCE(ep->busy_poll_budget);
|
|
bool prefer_busy_poll = READ_ONCE(ep->prefer_busy_poll);
|
|
|
|
if (!budget)
|
|
budget = BUSY_POLL_BUDGET;
|
|
|
|
if (napi_id >= MIN_NAPI_ID && ep_busy_loop_on(ep)) {
|
|
napi_busy_loop(napi_id, nonblock ? NULL : ep_busy_loop_end,
|
|
ep, prefer_busy_poll, budget);
|
|
if (ep_events_available(ep))
|
|
return true;
|
|
/*
|
|
* Busy poll timed out. Drop NAPI ID for now, we can add
|
|
* it back in when we have moved a socket with a valid NAPI
|
|
* ID onto the ready list.
|
|
*/
|
|
ep->napi_id = 0;
|
|
return false;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* Set epoll busy poll NAPI ID from sk.
|
|
*/
|
|
static inline void ep_set_busy_poll_napi_id(struct epitem *epi)
|
|
{
|
|
struct eventpoll *ep = epi->ep;
|
|
unsigned int napi_id;
|
|
struct socket *sock;
|
|
struct sock *sk;
|
|
|
|
if (!ep_busy_loop_on(ep))
|
|
return;
|
|
|
|
sock = sock_from_file(epi->ffd.file);
|
|
if (!sock)
|
|
return;
|
|
|
|
sk = sock->sk;
|
|
if (!sk)
|
|
return;
|
|
|
|
napi_id = READ_ONCE(sk->sk_napi_id);
|
|
|
|
/* Non-NAPI IDs can be rejected
|
|
* or
|
|
* Nothing to do if we already have this ID
|
|
*/
|
|
if (napi_id < MIN_NAPI_ID || napi_id == ep->napi_id)
|
|
return;
|
|
|
|
/* record NAPI ID for use in next busy poll */
|
|
ep->napi_id = napi_id;
|
|
}
|
|
|
|
static long ep_eventpoll_bp_ioctl(struct file *file, unsigned int cmd,
|
|
unsigned long arg)
|
|
{
|
|
struct eventpoll *ep = file->private_data;
|
|
void __user *uarg = (void __user *)arg;
|
|
struct epoll_params epoll_params;
|
|
|
|
switch (cmd) {
|
|
case EPIOCSPARAMS:
|
|
if (copy_from_user(&epoll_params, uarg, sizeof(epoll_params)))
|
|
return -EFAULT;
|
|
|
|
/* pad byte must be zero */
|
|
if (epoll_params.__pad)
|
|
return -EINVAL;
|
|
|
|
if (epoll_params.busy_poll_usecs > S32_MAX)
|
|
return -EINVAL;
|
|
|
|
if (epoll_params.prefer_busy_poll > 1)
|
|
return -EINVAL;
|
|
|
|
if (epoll_params.busy_poll_budget > NAPI_POLL_WEIGHT &&
|
|
!capable(CAP_NET_ADMIN))
|
|
return -EPERM;
|
|
|
|
WRITE_ONCE(ep->busy_poll_usecs, epoll_params.busy_poll_usecs);
|
|
WRITE_ONCE(ep->busy_poll_budget, epoll_params.busy_poll_budget);
|
|
WRITE_ONCE(ep->prefer_busy_poll, epoll_params.prefer_busy_poll);
|
|
return 0;
|
|
case EPIOCGPARAMS:
|
|
memset(&epoll_params, 0, sizeof(epoll_params));
|
|
epoll_params.busy_poll_usecs = READ_ONCE(ep->busy_poll_usecs);
|
|
epoll_params.busy_poll_budget = READ_ONCE(ep->busy_poll_budget);
|
|
epoll_params.prefer_busy_poll = READ_ONCE(ep->prefer_busy_poll);
|
|
if (copy_to_user(uarg, &epoll_params, sizeof(epoll_params)))
|
|
return -EFAULT;
|
|
return 0;
|
|
default:
|
|
return -ENOIOCTLCMD;
|
|
}
|
|
}
|
|
|
|
#else
|
|
|
|
static inline bool ep_busy_loop(struct eventpoll *ep, int nonblock)
|
|
{
|
|
return false;
|
|
}
|
|
|
|
static inline void ep_set_busy_poll_napi_id(struct epitem *epi)
|
|
{
|
|
}
|
|
|
|
static long ep_eventpoll_bp_ioctl(struct file *file, unsigned int cmd,
|
|
unsigned long arg)
|
|
{
|
|
return -EOPNOTSUPP;
|
|
}
|
|
|
|
#endif /* CONFIG_NET_RX_BUSY_POLL */
|
|
|
|
/*
|
|
* As described in commit 0ccf831cb lockdep: annotate epoll
|
|
* the use of wait queues used by epoll is done in a very controlled
|
|
* manner. Wake ups can nest inside each other, but are never done
|
|
* with the same locking. For example:
|
|
*
|
|
* dfd = socket(...);
|
|
* efd1 = epoll_create();
|
|
* efd2 = epoll_create();
|
|
* epoll_ctl(efd1, EPOLL_CTL_ADD, dfd, ...);
|
|
* epoll_ctl(efd2, EPOLL_CTL_ADD, efd1, ...);
|
|
*
|
|
* When a packet arrives to the device underneath "dfd", the net code will
|
|
* issue a wake_up() on its poll wake list. Epoll (efd1) has installed a
|
|
* callback wakeup entry on that queue, and the wake_up() performed by the
|
|
* "dfd" net code will end up in ep_poll_callback(). At this point epoll
|
|
* (efd1) notices that it may have some event ready, so it needs to wake up
|
|
* the waiters on its poll wait list (efd2). So it calls ep_poll_safewake()
|
|
* that ends up in another wake_up(), after having checked about the
|
|
* recursion constraints. That are, no more than EP_MAX_NESTS, to avoid
|
|
* stack blasting.
|
|
*
|
|
* When CONFIG_DEBUG_LOCK_ALLOC is enabled, make sure lockdep can handle
|
|
* this special case of epoll.
|
|
*/
|
|
#ifdef CONFIG_DEBUG_LOCK_ALLOC
|
|
|
|
static void ep_poll_safewake(struct eventpoll *ep, struct epitem *epi,
|
|
unsigned pollflags)
|
|
{
|
|
struct eventpoll *ep_src;
|
|
unsigned long flags;
|
|
u8 nests = 0;
|
|
|
|
/*
|
|
* To set the subclass or nesting level for spin_lock_irqsave_nested()
|
|
* it might be natural to create a per-cpu nest count. However, since
|
|
* we can recurse on ep->poll_wait.lock, and a non-raw spinlock can
|
|
* schedule() in the -rt kernel, the per-cpu variable are no longer
|
|
* protected. Thus, we are introducing a per eventpoll nest field.
|
|
* If we are not being call from ep_poll_callback(), epi is NULL and
|
|
* we are at the first level of nesting, 0. Otherwise, we are being
|
|
* called from ep_poll_callback() and if a previous wakeup source is
|
|
* not an epoll file itself, we are at depth 1 since the wakeup source
|
|
* is depth 0. If the wakeup source is a previous epoll file in the
|
|
* wakeup chain then we use its nests value and record ours as
|
|
* nests + 1. The previous epoll file nests value is stable since its
|
|
* already holding its own poll_wait.lock.
|
|
*/
|
|
if (epi) {
|
|
if ((is_file_epoll(epi->ffd.file))) {
|
|
ep_src = epi->ffd.file->private_data;
|
|
nests = ep_src->nests;
|
|
} else {
|
|
nests = 1;
|
|
}
|
|
}
|
|
spin_lock_irqsave_nested(&ep->poll_wait.lock, flags, nests);
|
|
ep->nests = nests + 1;
|
|
wake_up_locked_poll(&ep->poll_wait, EPOLLIN | pollflags);
|
|
ep->nests = 0;
|
|
spin_unlock_irqrestore(&ep->poll_wait.lock, flags);
|
|
}
|
|
|
|
#else
|
|
|
|
static void ep_poll_safewake(struct eventpoll *ep, struct epitem *epi,
|
|
__poll_t pollflags)
|
|
{
|
|
wake_up_poll(&ep->poll_wait, EPOLLIN | pollflags);
|
|
}
|
|
|
|
#endif
|
|
|
|
static void ep_remove_wait_queue(struct eppoll_entry *pwq)
|
|
{
|
|
wait_queue_head_t *whead;
|
|
|
|
rcu_read_lock();
|
|
/*
|
|
* If it is cleared by POLLFREE, it should be rcu-safe.
|
|
* If we read NULL we need a barrier paired with
|
|
* smp_store_release() in ep_poll_callback(), otherwise
|
|
* we rely on whead->lock.
|
|
*/
|
|
whead = smp_load_acquire(&pwq->whead);
|
|
if (whead)
|
|
remove_wait_queue(whead, &pwq->wait);
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
/*
|
|
* This function unregisters poll callbacks from the associated file
|
|
* descriptor. Must be called with "mtx" held.
|
|
*/
|
|
static void ep_unregister_pollwait(struct eventpoll *ep, struct epitem *epi)
|
|
{
|
|
struct eppoll_entry **p = &epi->pwqlist;
|
|
struct eppoll_entry *pwq;
|
|
|
|
while ((pwq = *p) != NULL) {
|
|
*p = pwq->next;
|
|
ep_remove_wait_queue(pwq);
|
|
kmem_cache_free(pwq_cache, pwq);
|
|
}
|
|
}
|
|
|
|
/* call only when ep->mtx is held */
|
|
static inline struct wakeup_source *ep_wakeup_source(struct epitem *epi)
|
|
{
|
|
return rcu_dereference_check(epi->ws, lockdep_is_held(&epi->ep->mtx));
|
|
}
|
|
|
|
/* call only when ep->mtx is held */
|
|
static inline void ep_pm_stay_awake(struct epitem *epi)
|
|
{
|
|
struct wakeup_source *ws = ep_wakeup_source(epi);
|
|
|
|
if (ws)
|
|
__pm_stay_awake(ws);
|
|
}
|
|
|
|
static inline bool ep_has_wakeup_source(struct epitem *epi)
|
|
{
|
|
return rcu_access_pointer(epi->ws) ? true : false;
|
|
}
|
|
|
|
/* call when ep->mtx cannot be held (ep_poll_callback) */
|
|
static inline void ep_pm_stay_awake_rcu(struct epitem *epi)
|
|
{
|
|
struct wakeup_source *ws;
|
|
|
|
rcu_read_lock();
|
|
ws = rcu_dereference(epi->ws);
|
|
if (ws)
|
|
__pm_stay_awake(ws);
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
|
|
/*
|
|
* ep->mutex needs to be held because we could be hit by
|
|
* eventpoll_release_file() and epoll_ctl().
|
|
*/
|
|
static void ep_start_scan(struct eventpoll *ep, struct list_head *txlist)
|
|
{
|
|
/*
|
|
* Steal the ready list, and re-init the original one to the
|
|
* empty list. Also, set ep->ovflist to NULL so that events
|
|
* happening while looping w/out locks, are not lost. We cannot
|
|
* have the poll callback to queue directly on ep->rdllist,
|
|
* because we want the "sproc" callback to be able to do it
|
|
* in a lockless way.
|
|
*/
|
|
lockdep_assert_irqs_enabled();
|
|
write_lock_irq(&ep->lock);
|
|
list_splice_init(&ep->rdllist, txlist);
|
|
WRITE_ONCE(ep->ovflist, NULL);
|
|
write_unlock_irq(&ep->lock);
|
|
}
|
|
|
|
static void ep_done_scan(struct eventpoll *ep,
|
|
struct list_head *txlist)
|
|
{
|
|
struct epitem *epi, *nepi;
|
|
|
|
write_lock_irq(&ep->lock);
|
|
/*
|
|
* During the time we spent inside the "sproc" callback, some
|
|
* other events might have been queued by the poll callback.
|
|
* We re-insert them inside the main ready-list here.
|
|
*/
|
|
for (nepi = READ_ONCE(ep->ovflist); (epi = nepi) != NULL;
|
|
nepi = epi->next, epi->next = EP_UNACTIVE_PTR) {
|
|
/*
|
|
* We need to check if the item is already in the list.
|
|
* During the "sproc" callback execution time, items are
|
|
* queued into ->ovflist but the "txlist" might already
|
|
* contain them, and the list_splice() below takes care of them.
|
|
*/
|
|
if (!ep_is_linked(epi)) {
|
|
/*
|
|
* ->ovflist is LIFO, so we have to reverse it in order
|
|
* to keep in FIFO.
|
|
*/
|
|
list_add(&epi->rdllink, &ep->rdllist);
|
|
ep_pm_stay_awake(epi);
|
|
}
|
|
}
|
|
/*
|
|
* We need to set back ep->ovflist to EP_UNACTIVE_PTR, so that after
|
|
* releasing the lock, events will be queued in the normal way inside
|
|
* ep->rdllist.
|
|
*/
|
|
WRITE_ONCE(ep->ovflist, EP_UNACTIVE_PTR);
|
|
|
|
/*
|
|
* Quickly re-inject items left on "txlist".
|
|
*/
|
|
list_splice(txlist, &ep->rdllist);
|
|
__pm_relax(ep->ws);
|
|
|
|
if (!list_empty(&ep->rdllist)) {
|
|
if (waitqueue_active(&ep->wq))
|
|
wake_up(&ep->wq);
|
|
}
|
|
|
|
write_unlock_irq(&ep->lock);
|
|
}
|
|
|
|
static void ep_get(struct eventpoll *ep)
|
|
{
|
|
refcount_inc(&ep->refcount);
|
|
}
|
|
|
|
/*
|
|
* Returns true if the event poll can be disposed
|
|
*/
|
|
static bool ep_refcount_dec_and_test(struct eventpoll *ep)
|
|
{
|
|
if (!refcount_dec_and_test(&ep->refcount))
|
|
return false;
|
|
|
|
WARN_ON_ONCE(!RB_EMPTY_ROOT(&ep->rbr.rb_root));
|
|
return true;
|
|
}
|
|
|
|
static void ep_free(struct eventpoll *ep)
|
|
{
|
|
mutex_destroy(&ep->mtx);
|
|
free_uid(ep->user);
|
|
wakeup_source_unregister(ep->ws);
|
|
kfree(ep);
|
|
}
|
|
|
|
/*
|
|
* Removes a "struct epitem" from the eventpoll RB tree and deallocates
|
|
* all the associated resources. Must be called with "mtx" held.
|
|
* If the dying flag is set, do the removal only if force is true.
|
|
* This prevents ep_clear_and_put() from dropping all the ep references
|
|
* while running concurrently with eventpoll_release_file().
|
|
* Returns true if the eventpoll can be disposed.
|
|
*/
|
|
static bool __ep_remove(struct eventpoll *ep, struct epitem *epi, bool force)
|
|
{
|
|
struct file *file = epi->ffd.file;
|
|
struct epitems_head *to_free;
|
|
struct hlist_head *head;
|
|
|
|
lockdep_assert_irqs_enabled();
|
|
|
|
/*
|
|
* Removes poll wait queue hooks.
|
|
*/
|
|
ep_unregister_pollwait(ep, epi);
|
|
|
|
/* Remove the current item from the list of epoll hooks */
|
|
spin_lock(&file->f_lock);
|
|
if (epi->dying && !force) {
|
|
spin_unlock(&file->f_lock);
|
|
return false;
|
|
}
|
|
|
|
to_free = NULL;
|
|
head = file->f_ep;
|
|
if (head->first == &epi->fllink && !epi->fllink.next) {
|
|
file->f_ep = NULL;
|
|
if (!is_file_epoll(file)) {
|
|
struct epitems_head *v;
|
|
v = container_of(head, struct epitems_head, epitems);
|
|
if (!smp_load_acquire(&v->next))
|
|
to_free = v;
|
|
}
|
|
}
|
|
hlist_del_rcu(&epi->fllink);
|
|
spin_unlock(&file->f_lock);
|
|
free_ephead(to_free);
|
|
|
|
rb_erase_cached(&epi->rbn, &ep->rbr);
|
|
|
|
write_lock_irq(&ep->lock);
|
|
if (ep_is_linked(epi))
|
|
list_del_init(&epi->rdllink);
|
|
write_unlock_irq(&ep->lock);
|
|
|
|
wakeup_source_unregister(ep_wakeup_source(epi));
|
|
/*
|
|
* At this point it is safe to free the eventpoll item. Use the union
|
|
* field epi->rcu, since we are trying to minimize the size of
|
|
* 'struct epitem'. The 'rbn' field is no longer in use. Protected by
|
|
* ep->mtx. The rcu read side, reverse_path_check_proc(), does not make
|
|
* use of the rbn field.
|
|
*/
|
|
kfree_rcu(epi, rcu);
|
|
|
|
percpu_counter_dec(&ep->user->epoll_watches);
|
|
return ep_refcount_dec_and_test(ep);
|
|
}
|
|
|
|
/*
|
|
* ep_remove variant for callers owing an additional reference to the ep
|
|
*/
|
|
static void ep_remove_safe(struct eventpoll *ep, struct epitem *epi)
|
|
{
|
|
WARN_ON_ONCE(__ep_remove(ep, epi, false));
|
|
}
|
|
|
|
static void ep_clear_and_put(struct eventpoll *ep)
|
|
{
|
|
struct rb_node *rbp, *next;
|
|
struct epitem *epi;
|
|
bool dispose;
|
|
|
|
/* We need to release all tasks waiting for these file */
|
|
if (waitqueue_active(&ep->poll_wait))
|
|
ep_poll_safewake(ep, NULL, 0);
|
|
|
|
mutex_lock(&ep->mtx);
|
|
|
|
/*
|
|
* Walks through the whole tree by unregistering poll callbacks.
|
|
*/
|
|
for (rbp = rb_first_cached(&ep->rbr); rbp; rbp = rb_next(rbp)) {
|
|
epi = rb_entry(rbp, struct epitem, rbn);
|
|
|
|
ep_unregister_pollwait(ep, epi);
|
|
cond_resched();
|
|
}
|
|
|
|
/*
|
|
* Walks through the whole tree and try to free each "struct epitem".
|
|
* Note that ep_remove_safe() will not remove the epitem in case of a
|
|
* racing eventpoll_release_file(); the latter will do the removal.
|
|
* At this point we are sure no poll callbacks will be lingering around.
|
|
* Since we still own a reference to the eventpoll struct, the loop can't
|
|
* dispose it.
|
|
*/
|
|
for (rbp = rb_first_cached(&ep->rbr); rbp; rbp = next) {
|
|
next = rb_next(rbp);
|
|
epi = rb_entry(rbp, struct epitem, rbn);
|
|
ep_remove_safe(ep, epi);
|
|
cond_resched();
|
|
}
|
|
|
|
dispose = ep_refcount_dec_and_test(ep);
|
|
mutex_unlock(&ep->mtx);
|
|
|
|
if (dispose)
|
|
ep_free(ep);
|
|
}
|
|
|
|
static long ep_eventpoll_ioctl(struct file *file, unsigned int cmd,
|
|
unsigned long arg)
|
|
{
|
|
int ret;
|
|
|
|
if (!is_file_epoll(file))
|
|
return -EINVAL;
|
|
|
|
switch (cmd) {
|
|
case EPIOCSPARAMS:
|
|
case EPIOCGPARAMS:
|
|
ret = ep_eventpoll_bp_ioctl(file, cmd, arg);
|
|
break;
|
|
default:
|
|
ret = -EINVAL;
|
|
break;
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int ep_eventpoll_release(struct inode *inode, struct file *file)
|
|
{
|
|
struct eventpoll *ep = file->private_data;
|
|
|
|
if (ep)
|
|
ep_clear_and_put(ep);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static __poll_t ep_item_poll(const struct epitem *epi, poll_table *pt, int depth);
|
|
|
|
static __poll_t __ep_eventpoll_poll(struct file *file, poll_table *wait, int depth)
|
|
{
|
|
struct eventpoll *ep = file->private_data;
|
|
LIST_HEAD(txlist);
|
|
struct epitem *epi, *tmp;
|
|
poll_table pt;
|
|
__poll_t res = 0;
|
|
|
|
init_poll_funcptr(&pt, NULL);
|
|
|
|
/* Insert inside our poll wait queue */
|
|
poll_wait(file, &ep->poll_wait, wait);
|
|
|
|
/*
|
|
* Proceed to find out if wanted events are really available inside
|
|
* the ready list.
|
|
*/
|
|
mutex_lock_nested(&ep->mtx, depth);
|
|
ep_start_scan(ep, &txlist);
|
|
list_for_each_entry_safe(epi, tmp, &txlist, rdllink) {
|
|
if (ep_item_poll(epi, &pt, depth + 1)) {
|
|
res = EPOLLIN | EPOLLRDNORM;
|
|
break;
|
|
} else {
|
|
/*
|
|
* Item has been dropped into the ready list by the poll
|
|
* callback, but it's not actually ready, as far as
|
|
* caller requested events goes. We can remove it here.
|
|
*/
|
|
__pm_relax(ep_wakeup_source(epi));
|
|
list_del_init(&epi->rdllink);
|
|
}
|
|
}
|
|
ep_done_scan(ep, &txlist);
|
|
mutex_unlock(&ep->mtx);
|
|
return res;
|
|
}
|
|
|
|
/*
|
|
* Differs from ep_eventpoll_poll() in that internal callers already have
|
|
* the ep->mtx so we need to start from depth=1, such that mutex_lock_nested()
|
|
* is correctly annotated.
|
|
*/
|
|
static __poll_t ep_item_poll(const struct epitem *epi, poll_table *pt,
|
|
int depth)
|
|
{
|
|
struct file *file = epi->ffd.file;
|
|
__poll_t res;
|
|
|
|
pt->_key = epi->event.events;
|
|
if (!is_file_epoll(file))
|
|
res = vfs_poll(file, pt);
|
|
else
|
|
res = __ep_eventpoll_poll(file, pt, depth);
|
|
return res & epi->event.events;
|
|
}
|
|
|
|
static __poll_t ep_eventpoll_poll(struct file *file, poll_table *wait)
|
|
{
|
|
return __ep_eventpoll_poll(file, wait, 0);
|
|
}
|
|
|
|
#ifdef CONFIG_PROC_FS
|
|
static void ep_show_fdinfo(struct seq_file *m, struct file *f)
|
|
{
|
|
struct eventpoll *ep = f->private_data;
|
|
struct rb_node *rbp;
|
|
|
|
mutex_lock(&ep->mtx);
|
|
for (rbp = rb_first_cached(&ep->rbr); rbp; rbp = rb_next(rbp)) {
|
|
struct epitem *epi = rb_entry(rbp, struct epitem, rbn);
|
|
struct inode *inode = file_inode(epi->ffd.file);
|
|
|
|
seq_printf(m, "tfd: %8d events: %8x data: %16llx "
|
|
" pos:%lli ino:%lx sdev:%x\n",
|
|
epi->ffd.fd, epi->event.events,
|
|
(long long)epi->event.data,
|
|
(long long)epi->ffd.file->f_pos,
|
|
inode->i_ino, inode->i_sb->s_dev);
|
|
if (seq_has_overflowed(m))
|
|
break;
|
|
}
|
|
mutex_unlock(&ep->mtx);
|
|
}
|
|
#endif
|
|
|
|
/* File callbacks that implement the eventpoll file behaviour */
|
|
static const struct file_operations eventpoll_fops = {
|
|
#ifdef CONFIG_PROC_FS
|
|
.show_fdinfo = ep_show_fdinfo,
|
|
#endif
|
|
.release = ep_eventpoll_release,
|
|
.poll = ep_eventpoll_poll,
|
|
.llseek = noop_llseek,
|
|
.unlocked_ioctl = ep_eventpoll_ioctl,
|
|
.compat_ioctl = compat_ptr_ioctl,
|
|
};
|
|
|
|
/*
|
|
* This is called from eventpoll_release() to unlink files from the eventpoll
|
|
* interface. We need to have this facility to cleanup correctly files that are
|
|
* closed without being removed from the eventpoll interface.
|
|
*/
|
|
void eventpoll_release_file(struct file *file)
|
|
{
|
|
struct eventpoll *ep;
|
|
struct epitem *epi;
|
|
bool dispose;
|
|
|
|
/*
|
|
* Use the 'dying' flag to prevent a concurrent ep_clear_and_put() from
|
|
* touching the epitems list before eventpoll_release_file() can access
|
|
* the ep->mtx.
|
|
*/
|
|
again:
|
|
spin_lock(&file->f_lock);
|
|
if (file->f_ep && file->f_ep->first) {
|
|
epi = hlist_entry(file->f_ep->first, struct epitem, fllink);
|
|
epi->dying = true;
|
|
spin_unlock(&file->f_lock);
|
|
|
|
/*
|
|
* ep access is safe as we still own a reference to the ep
|
|
* struct
|
|
*/
|
|
ep = epi->ep;
|
|
mutex_lock(&ep->mtx);
|
|
dispose = __ep_remove(ep, epi, true);
|
|
mutex_unlock(&ep->mtx);
|
|
|
|
if (dispose)
|
|
ep_free(ep);
|
|
goto again;
|
|
}
|
|
spin_unlock(&file->f_lock);
|
|
}
|
|
|
|
static int ep_alloc(struct eventpoll **pep)
|
|
{
|
|
struct eventpoll *ep;
|
|
|
|
ep = kzalloc(sizeof(*ep), GFP_KERNEL);
|
|
if (unlikely(!ep))
|
|
return -ENOMEM;
|
|
|
|
mutex_init(&ep->mtx);
|
|
rwlock_init(&ep->lock);
|
|
init_waitqueue_head(&ep->wq);
|
|
init_waitqueue_head(&ep->poll_wait);
|
|
INIT_LIST_HEAD(&ep->rdllist);
|
|
ep->rbr = RB_ROOT_CACHED;
|
|
ep->ovflist = EP_UNACTIVE_PTR;
|
|
ep->user = get_current_user();
|
|
refcount_set(&ep->refcount, 1);
|
|
|
|
*pep = ep;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Search the file inside the eventpoll tree. The RB tree operations
|
|
* are protected by the "mtx" mutex, and ep_find() must be called with
|
|
* "mtx" held.
|
|
*/
|
|
static struct epitem *ep_find(struct eventpoll *ep, struct file *file, int fd)
|
|
{
|
|
int kcmp;
|
|
struct rb_node *rbp;
|
|
struct epitem *epi, *epir = NULL;
|
|
struct epoll_filefd ffd;
|
|
|
|
ep_set_ffd(&ffd, file, fd);
|
|
for (rbp = ep->rbr.rb_root.rb_node; rbp; ) {
|
|
epi = rb_entry(rbp, struct epitem, rbn);
|
|
kcmp = ep_cmp_ffd(&ffd, &epi->ffd);
|
|
if (kcmp > 0)
|
|
rbp = rbp->rb_right;
|
|
else if (kcmp < 0)
|
|
rbp = rbp->rb_left;
|
|
else {
|
|
epir = epi;
|
|
break;
|
|
}
|
|
}
|
|
|
|
return epir;
|
|
}
|
|
|
|
#ifdef CONFIG_KCMP
|
|
static struct epitem *ep_find_tfd(struct eventpoll *ep, int tfd, unsigned long toff)
|
|
{
|
|
struct rb_node *rbp;
|
|
struct epitem *epi;
|
|
|
|
for (rbp = rb_first_cached(&ep->rbr); rbp; rbp = rb_next(rbp)) {
|
|
epi = rb_entry(rbp, struct epitem, rbn);
|
|
if (epi->ffd.fd == tfd) {
|
|
if (toff == 0)
|
|
return epi;
|
|
else
|
|
toff--;
|
|
}
|
|
cond_resched();
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
struct file *get_epoll_tfile_raw_ptr(struct file *file, int tfd,
|
|
unsigned long toff)
|
|
{
|
|
struct file *file_raw;
|
|
struct eventpoll *ep;
|
|
struct epitem *epi;
|
|
|
|
if (!is_file_epoll(file))
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
ep = file->private_data;
|
|
|
|
mutex_lock(&ep->mtx);
|
|
epi = ep_find_tfd(ep, tfd, toff);
|
|
if (epi)
|
|
file_raw = epi->ffd.file;
|
|
else
|
|
file_raw = ERR_PTR(-ENOENT);
|
|
mutex_unlock(&ep->mtx);
|
|
|
|
return file_raw;
|
|
}
|
|
#endif /* CONFIG_KCMP */
|
|
|
|
/*
|
|
* Adds a new entry to the tail of the list in a lockless way, i.e.
|
|
* multiple CPUs are allowed to call this function concurrently.
|
|
*
|
|
* Beware: it is necessary to prevent any other modifications of the
|
|
* existing list until all changes are completed, in other words
|
|
* concurrent list_add_tail_lockless() calls should be protected
|
|
* with a read lock, where write lock acts as a barrier which
|
|
* makes sure all list_add_tail_lockless() calls are fully
|
|
* completed.
|
|
*
|
|
* Also an element can be locklessly added to the list only in one
|
|
* direction i.e. either to the tail or to the head, otherwise
|
|
* concurrent access will corrupt the list.
|
|
*
|
|
* Return: %false if element has been already added to the list, %true
|
|
* otherwise.
|
|
*/
|
|
static inline bool list_add_tail_lockless(struct list_head *new,
|
|
struct list_head *head)
|
|
{
|
|
struct list_head *prev;
|
|
|
|
/*
|
|
* This is simple 'new->next = head' operation, but cmpxchg()
|
|
* is used in order to detect that same element has been just
|
|
* added to the list from another CPU: the winner observes
|
|
* new->next == new.
|
|
*/
|
|
if (!try_cmpxchg(&new->next, &new, head))
|
|
return false;
|
|
|
|
/*
|
|
* Initially ->next of a new element must be updated with the head
|
|
* (we are inserting to the tail) and only then pointers are atomically
|
|
* exchanged. XCHG guarantees memory ordering, thus ->next should be
|
|
* updated before pointers are actually swapped and pointers are
|
|
* swapped before prev->next is updated.
|
|
*/
|
|
|
|
prev = xchg(&head->prev, new);
|
|
|
|
/*
|
|
* It is safe to modify prev->next and new->prev, because a new element
|
|
* is added only to the tail and new->next is updated before XCHG.
|
|
*/
|
|
|
|
prev->next = new;
|
|
new->prev = prev;
|
|
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* Chains a new epi entry to the tail of the ep->ovflist in a lockless way,
|
|
* i.e. multiple CPUs are allowed to call this function concurrently.
|
|
*
|
|
* Return: %false if epi element has been already chained, %true otherwise.
|
|
*/
|
|
static inline bool chain_epi_lockless(struct epitem *epi)
|
|
{
|
|
struct eventpoll *ep = epi->ep;
|
|
|
|
/* Fast preliminary check */
|
|
if (epi->next != EP_UNACTIVE_PTR)
|
|
return false;
|
|
|
|
/* Check that the same epi has not been just chained from another CPU */
|
|
if (cmpxchg(&epi->next, EP_UNACTIVE_PTR, NULL) != EP_UNACTIVE_PTR)
|
|
return false;
|
|
|
|
/* Atomically exchange tail */
|
|
epi->next = xchg(&ep->ovflist, epi);
|
|
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* This is the callback that is passed to the wait queue wakeup
|
|
* mechanism. It is called by the stored file descriptors when they
|
|
* have events to report.
|
|
*
|
|
* This callback takes a read lock in order not to contend with concurrent
|
|
* events from another file descriptor, thus all modifications to ->rdllist
|
|
* or ->ovflist are lockless. Read lock is paired with the write lock from
|
|
* ep_start/done_scan(), which stops all list modifications and guarantees
|
|
* that lists state is seen correctly.
|
|
*
|
|
* Another thing worth to mention is that ep_poll_callback() can be called
|
|
* concurrently for the same @epi from different CPUs if poll table was inited
|
|
* with several wait queues entries. Plural wakeup from different CPUs of a
|
|
* single wait queue is serialized by wq.lock, but the case when multiple wait
|
|
* queues are used should be detected accordingly. This is detected using
|
|
* cmpxchg() operation.
|
|
*/
|
|
static int ep_poll_callback(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
|
|
{
|
|
int pwake = 0;
|
|
struct epitem *epi = ep_item_from_wait(wait);
|
|
struct eventpoll *ep = epi->ep;
|
|
__poll_t pollflags = key_to_poll(key);
|
|
unsigned long flags;
|
|
int ewake = 0;
|
|
|
|
read_lock_irqsave(&ep->lock, flags);
|
|
|
|
ep_set_busy_poll_napi_id(epi);
|
|
|
|
/*
|
|
* If the event mask does not contain any poll(2) event, we consider the
|
|
* descriptor to be disabled. This condition is likely the effect of the
|
|
* EPOLLONESHOT bit that disables the descriptor when an event is received,
|
|
* until the next EPOLL_CTL_MOD will be issued.
|
|
*/
|
|
if (!(epi->event.events & ~EP_PRIVATE_BITS))
|
|
goto out_unlock;
|
|
|
|
/*
|
|
* Check the events coming with the callback. At this stage, not
|
|
* every device reports the events in the "key" parameter of the
|
|
* callback. We need to be able to handle both cases here, hence the
|
|
* test for "key" != NULL before the event match test.
|
|
*/
|
|
if (pollflags && !(pollflags & epi->event.events))
|
|
goto out_unlock;
|
|
|
|
/*
|
|
* If we are transferring events to userspace, we can hold no locks
|
|
* (because we're accessing user memory, and because of linux f_op->poll()
|
|
* semantics). All the events that happen during that period of time are
|
|
* chained in ep->ovflist and requeued later on.
|
|
*/
|
|
if (READ_ONCE(ep->ovflist) != EP_UNACTIVE_PTR) {
|
|
if (chain_epi_lockless(epi))
|
|
ep_pm_stay_awake_rcu(epi);
|
|
} else if (!ep_is_linked(epi)) {
|
|
/* In the usual case, add event to ready list. */
|
|
if (list_add_tail_lockless(&epi->rdllink, &ep->rdllist))
|
|
ep_pm_stay_awake_rcu(epi);
|
|
}
|
|
|
|
/*
|
|
* Wake up ( if active ) both the eventpoll wait list and the ->poll()
|
|
* wait list.
|
|
*/
|
|
if (waitqueue_active(&ep->wq)) {
|
|
if ((epi->event.events & EPOLLEXCLUSIVE) &&
|
|
!(pollflags & POLLFREE)) {
|
|
switch (pollflags & EPOLLINOUT_BITS) {
|
|
case EPOLLIN:
|
|
if (epi->event.events & EPOLLIN)
|
|
ewake = 1;
|
|
break;
|
|
case EPOLLOUT:
|
|
if (epi->event.events & EPOLLOUT)
|
|
ewake = 1;
|
|
break;
|
|
case 0:
|
|
ewake = 1;
|
|
break;
|
|
}
|
|
}
|
|
wake_up(&ep->wq);
|
|
}
|
|
if (waitqueue_active(&ep->poll_wait))
|
|
pwake++;
|
|
|
|
out_unlock:
|
|
read_unlock_irqrestore(&ep->lock, flags);
|
|
|
|
/* We have to call this outside the lock */
|
|
if (pwake)
|
|
ep_poll_safewake(ep, epi, pollflags & EPOLL_URING_WAKE);
|
|
|
|
if (!(epi->event.events & EPOLLEXCLUSIVE))
|
|
ewake = 1;
|
|
|
|
if (pollflags & POLLFREE) {
|
|
/*
|
|
* If we race with ep_remove_wait_queue() it can miss
|
|
* ->whead = NULL and do another remove_wait_queue() after
|
|
* us, so we can't use __remove_wait_queue().
|
|
*/
|
|
list_del_init(&wait->entry);
|
|
/*
|
|
* ->whead != NULL protects us from the race with
|
|
* ep_clear_and_put() or ep_remove(), ep_remove_wait_queue()
|
|
* takes whead->lock held by the caller. Once we nullify it,
|
|
* nothing protects ep/epi or even wait.
|
|
*/
|
|
smp_store_release(&ep_pwq_from_wait(wait)->whead, NULL);
|
|
}
|
|
|
|
return ewake;
|
|
}
|
|
|
|
/*
|
|
* This is the callback that is used to add our wait queue to the
|
|
* target file wakeup lists.
|
|
*/
|
|
static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead,
|
|
poll_table *pt)
|
|
{
|
|
struct ep_pqueue *epq = container_of(pt, struct ep_pqueue, pt);
|
|
struct epitem *epi = epq->epi;
|
|
struct eppoll_entry *pwq;
|
|
|
|
if (unlikely(!epi)) // an earlier allocation has failed
|
|
return;
|
|
|
|
pwq = kmem_cache_alloc(pwq_cache, GFP_KERNEL);
|
|
if (unlikely(!pwq)) {
|
|
epq->epi = NULL;
|
|
return;
|
|
}
|
|
|
|
init_waitqueue_func_entry(&pwq->wait, ep_poll_callback);
|
|
pwq->whead = whead;
|
|
pwq->base = epi;
|
|
if (epi->event.events & EPOLLEXCLUSIVE)
|
|
add_wait_queue_exclusive(whead, &pwq->wait);
|
|
else
|
|
add_wait_queue(whead, &pwq->wait);
|
|
pwq->next = epi->pwqlist;
|
|
epi->pwqlist = pwq;
|
|
}
|
|
|
|
static void ep_rbtree_insert(struct eventpoll *ep, struct epitem *epi)
|
|
{
|
|
int kcmp;
|
|
struct rb_node **p = &ep->rbr.rb_root.rb_node, *parent = NULL;
|
|
struct epitem *epic;
|
|
bool leftmost = true;
|
|
|
|
while (*p) {
|
|
parent = *p;
|
|
epic = rb_entry(parent, struct epitem, rbn);
|
|
kcmp = ep_cmp_ffd(&epi->ffd, &epic->ffd);
|
|
if (kcmp > 0) {
|
|
p = &parent->rb_right;
|
|
leftmost = false;
|
|
} else
|
|
p = &parent->rb_left;
|
|
}
|
|
rb_link_node(&epi->rbn, parent, p);
|
|
rb_insert_color_cached(&epi->rbn, &ep->rbr, leftmost);
|
|
}
|
|
|
|
|
|
|
|
#define PATH_ARR_SIZE 5
|
|
/*
|
|
* These are the number paths of length 1 to 5, that we are allowing to emanate
|
|
* from a single file of interest. For example, we allow 1000 paths of length
|
|
* 1, to emanate from each file of interest. This essentially represents the
|
|
* potential wakeup paths, which need to be limited in order to avoid massive
|
|
* uncontrolled wakeup storms. The common use case should be a single ep which
|
|
* is connected to n file sources. In this case each file source has 1 path
|
|
* of length 1. Thus, the numbers below should be more than sufficient. These
|
|
* path limits are enforced during an EPOLL_CTL_ADD operation, since a modify
|
|
* and delete can't add additional paths. Protected by the epnested_mutex.
|
|
*/
|
|
static const int path_limits[PATH_ARR_SIZE] = { 1000, 500, 100, 50, 10 };
|
|
static int path_count[PATH_ARR_SIZE];
|
|
|
|
static int path_count_inc(int nests)
|
|
{
|
|
/* Allow an arbitrary number of depth 1 paths */
|
|
if (nests == 0)
|
|
return 0;
|
|
|
|
if (++path_count[nests] > path_limits[nests])
|
|
return -1;
|
|
return 0;
|
|
}
|
|
|
|
static void path_count_init(void)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < PATH_ARR_SIZE; i++)
|
|
path_count[i] = 0;
|
|
}
|
|
|
|
static int reverse_path_check_proc(struct hlist_head *refs, int depth)
|
|
{
|
|
int error = 0;
|
|
struct epitem *epi;
|
|
|
|
if (depth > EP_MAX_NESTS) /* too deep nesting */
|
|
return -1;
|
|
|
|
/* CTL_DEL can remove links here, but that can't increase our count */
|
|
hlist_for_each_entry_rcu(epi, refs, fllink) {
|
|
struct hlist_head *refs = &epi->ep->refs;
|
|
if (hlist_empty(refs))
|
|
error = path_count_inc(depth);
|
|
else
|
|
error = reverse_path_check_proc(refs, depth + 1);
|
|
if (error != 0)
|
|
break;
|
|
}
|
|
return error;
|
|
}
|
|
|
|
/**
|
|
* reverse_path_check - The tfile_check_list is list of epitem_head, which have
|
|
* links that are proposed to be newly added. We need to
|
|
* make sure that those added links don't add too many
|
|
* paths such that we will spend all our time waking up
|
|
* eventpoll objects.
|
|
*
|
|
* Return: %zero if the proposed links don't create too many paths,
|
|
* %-1 otherwise.
|
|
*/
|
|
static int reverse_path_check(void)
|
|
{
|
|
struct epitems_head *p;
|
|
|
|
for (p = tfile_check_list; p != EP_UNACTIVE_PTR; p = p->next) {
|
|
int error;
|
|
path_count_init();
|
|
rcu_read_lock();
|
|
error = reverse_path_check_proc(&p->epitems, 0);
|
|
rcu_read_unlock();
|
|
if (error)
|
|
return error;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int ep_create_wakeup_source(struct epitem *epi)
|
|
{
|
|
struct name_snapshot n;
|
|
struct wakeup_source *ws;
|
|
|
|
if (!epi->ep->ws) {
|
|
epi->ep->ws = wakeup_source_register(NULL, "eventpoll");
|
|
if (!epi->ep->ws)
|
|
return -ENOMEM;
|
|
}
|
|
|
|
take_dentry_name_snapshot(&n, epi->ffd.file->f_path.dentry);
|
|
ws = wakeup_source_register(NULL, n.name.name);
|
|
release_dentry_name_snapshot(&n);
|
|
|
|
if (!ws)
|
|
return -ENOMEM;
|
|
rcu_assign_pointer(epi->ws, ws);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* rare code path, only used when EPOLL_CTL_MOD removes a wakeup source */
|
|
static noinline void ep_destroy_wakeup_source(struct epitem *epi)
|
|
{
|
|
struct wakeup_source *ws = ep_wakeup_source(epi);
|
|
|
|
RCU_INIT_POINTER(epi->ws, NULL);
|
|
|
|
/*
|
|
* wait for ep_pm_stay_awake_rcu to finish, synchronize_rcu is
|
|
* used internally by wakeup_source_remove, too (called by
|
|
* wakeup_source_unregister), so we cannot use call_rcu
|
|
*/
|
|
synchronize_rcu();
|
|
wakeup_source_unregister(ws);
|
|
}
|
|
|
|
static int attach_epitem(struct file *file, struct epitem *epi)
|
|
{
|
|
struct epitems_head *to_free = NULL;
|
|
struct hlist_head *head = NULL;
|
|
struct eventpoll *ep = NULL;
|
|
|
|
if (is_file_epoll(file))
|
|
ep = file->private_data;
|
|
|
|
if (ep) {
|
|
head = &ep->refs;
|
|
} else if (!READ_ONCE(file->f_ep)) {
|
|
allocate:
|
|
to_free = kmem_cache_zalloc(ephead_cache, GFP_KERNEL);
|
|
if (!to_free)
|
|
return -ENOMEM;
|
|
head = &to_free->epitems;
|
|
}
|
|
spin_lock(&file->f_lock);
|
|
if (!file->f_ep) {
|
|
if (unlikely(!head)) {
|
|
spin_unlock(&file->f_lock);
|
|
goto allocate;
|
|
}
|
|
file->f_ep = head;
|
|
to_free = NULL;
|
|
}
|
|
hlist_add_head_rcu(&epi->fllink, file->f_ep);
|
|
spin_unlock(&file->f_lock);
|
|
free_ephead(to_free);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Must be called with "mtx" held.
|
|
*/
|
|
static int ep_insert(struct eventpoll *ep, const struct epoll_event *event,
|
|
struct file *tfile, int fd, int full_check)
|
|
{
|
|
int error, pwake = 0;
|
|
__poll_t revents;
|
|
struct epitem *epi;
|
|
struct ep_pqueue epq;
|
|
struct eventpoll *tep = NULL;
|
|
|
|
if (is_file_epoll(tfile))
|
|
tep = tfile->private_data;
|
|
|
|
lockdep_assert_irqs_enabled();
|
|
|
|
if (unlikely(percpu_counter_compare(&ep->user->epoll_watches,
|
|
max_user_watches) >= 0))
|
|
return -ENOSPC;
|
|
percpu_counter_inc(&ep->user->epoll_watches);
|
|
|
|
if (!(epi = kmem_cache_zalloc(epi_cache, GFP_KERNEL))) {
|
|
percpu_counter_dec(&ep->user->epoll_watches);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/* Item initialization follow here ... */
|
|
INIT_LIST_HEAD(&epi->rdllink);
|
|
epi->ep = ep;
|
|
ep_set_ffd(&epi->ffd, tfile, fd);
|
|
epi->event = *event;
|
|
epi->next = EP_UNACTIVE_PTR;
|
|
|
|
if (tep)
|
|
mutex_lock_nested(&tep->mtx, 1);
|
|
/* Add the current item to the list of active epoll hook for this file */
|
|
if (unlikely(attach_epitem(tfile, epi) < 0)) {
|
|
if (tep)
|
|
mutex_unlock(&tep->mtx);
|
|
kmem_cache_free(epi_cache, epi);
|
|
percpu_counter_dec(&ep->user->epoll_watches);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
if (full_check && !tep)
|
|
list_file(tfile);
|
|
|
|
/*
|
|
* Add the current item to the RB tree. All RB tree operations are
|
|
* protected by "mtx", and ep_insert() is called with "mtx" held.
|
|
*/
|
|
ep_rbtree_insert(ep, epi);
|
|
if (tep)
|
|
mutex_unlock(&tep->mtx);
|
|
|
|
/*
|
|
* ep_remove_safe() calls in the later error paths can't lead to
|
|
* ep_free() as the ep file itself still holds an ep reference.
|
|
*/
|
|
ep_get(ep);
|
|
|
|
/* now check if we've created too many backpaths */
|
|
if (unlikely(full_check && reverse_path_check())) {
|
|
ep_remove_safe(ep, epi);
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (epi->event.events & EPOLLWAKEUP) {
|
|
error = ep_create_wakeup_source(epi);
|
|
if (error) {
|
|
ep_remove_safe(ep, epi);
|
|
return error;
|
|
}
|
|
}
|
|
|
|
/* Initialize the poll table using the queue callback */
|
|
epq.epi = epi;
|
|
init_poll_funcptr(&epq.pt, ep_ptable_queue_proc);
|
|
|
|
/*
|
|
* Attach the item to the poll hooks and get current event bits.
|
|
* We can safely use the file* here because its usage count has
|
|
* been increased by the caller of this function. Note that after
|
|
* this operation completes, the poll callback can start hitting
|
|
* the new item.
|
|
*/
|
|
revents = ep_item_poll(epi, &epq.pt, 1);
|
|
|
|
/*
|
|
* We have to check if something went wrong during the poll wait queue
|
|
* install process. Namely an allocation for a wait queue failed due
|
|
* high memory pressure.
|
|
*/
|
|
if (unlikely(!epq.epi)) {
|
|
ep_remove_safe(ep, epi);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/* We have to drop the new item inside our item list to keep track of it */
|
|
write_lock_irq(&ep->lock);
|
|
|
|
/* record NAPI ID of new item if present */
|
|
ep_set_busy_poll_napi_id(epi);
|
|
|
|
/* If the file is already "ready" we drop it inside the ready list */
|
|
if (revents && !ep_is_linked(epi)) {
|
|
list_add_tail(&epi->rdllink, &ep->rdllist);
|
|
ep_pm_stay_awake(epi);
|
|
|
|
/* Notify waiting tasks that events are available */
|
|
if (waitqueue_active(&ep->wq))
|
|
wake_up(&ep->wq);
|
|
if (waitqueue_active(&ep->poll_wait))
|
|
pwake++;
|
|
}
|
|
|
|
write_unlock_irq(&ep->lock);
|
|
|
|
/* We have to call this outside the lock */
|
|
if (pwake)
|
|
ep_poll_safewake(ep, NULL, 0);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Modify the interest event mask by dropping an event if the new mask
|
|
* has a match in the current file status. Must be called with "mtx" held.
|
|
*/
|
|
static int ep_modify(struct eventpoll *ep, struct epitem *epi,
|
|
const struct epoll_event *event)
|
|
{
|
|
int pwake = 0;
|
|
poll_table pt;
|
|
|
|
lockdep_assert_irqs_enabled();
|
|
|
|
init_poll_funcptr(&pt, NULL);
|
|
|
|
/*
|
|
* Set the new event interest mask before calling f_op->poll();
|
|
* otherwise we might miss an event that happens between the
|
|
* f_op->poll() call and the new event set registering.
|
|
*/
|
|
epi->event.events = event->events; /* need barrier below */
|
|
epi->event.data = event->data; /* protected by mtx */
|
|
if (epi->event.events & EPOLLWAKEUP) {
|
|
if (!ep_has_wakeup_source(epi))
|
|
ep_create_wakeup_source(epi);
|
|
} else if (ep_has_wakeup_source(epi)) {
|
|
ep_destroy_wakeup_source(epi);
|
|
}
|
|
|
|
/*
|
|
* The following barrier has two effects:
|
|
*
|
|
* 1) Flush epi changes above to other CPUs. This ensures
|
|
* we do not miss events from ep_poll_callback if an
|
|
* event occurs immediately after we call f_op->poll().
|
|
* We need this because we did not take ep->lock while
|
|
* changing epi above (but ep_poll_callback does take
|
|
* ep->lock).
|
|
*
|
|
* 2) We also need to ensure we do not miss _past_ events
|
|
* when calling f_op->poll(). This barrier also
|
|
* pairs with the barrier in wq_has_sleeper (see
|
|
* comments for wq_has_sleeper).
|
|
*
|
|
* This barrier will now guarantee ep_poll_callback or f_op->poll
|
|
* (or both) will notice the readiness of an item.
|
|
*/
|
|
smp_mb();
|
|
|
|
/*
|
|
* Get current event bits. We can safely use the file* here because
|
|
* its usage count has been increased by the caller of this function.
|
|
* If the item is "hot" and it is not registered inside the ready
|
|
* list, push it inside.
|
|
*/
|
|
if (ep_item_poll(epi, &pt, 1)) {
|
|
write_lock_irq(&ep->lock);
|
|
if (!ep_is_linked(epi)) {
|
|
list_add_tail(&epi->rdllink, &ep->rdllist);
|
|
ep_pm_stay_awake(epi);
|
|
|
|
/* Notify waiting tasks that events are available */
|
|
if (waitqueue_active(&ep->wq))
|
|
wake_up(&ep->wq);
|
|
if (waitqueue_active(&ep->poll_wait))
|
|
pwake++;
|
|
}
|
|
write_unlock_irq(&ep->lock);
|
|
}
|
|
|
|
/* We have to call this outside the lock */
|
|
if (pwake)
|
|
ep_poll_safewake(ep, NULL, 0);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int ep_send_events(struct eventpoll *ep,
|
|
struct epoll_event __user *events, int maxevents)
|
|
{
|
|
struct epitem *epi, *tmp;
|
|
LIST_HEAD(txlist);
|
|
poll_table pt;
|
|
int res = 0;
|
|
|
|
/*
|
|
* Always short-circuit for fatal signals to allow threads to make a
|
|
* timely exit without the chance of finding more events available and
|
|
* fetching repeatedly.
|
|
*/
|
|
if (fatal_signal_pending(current))
|
|
return -EINTR;
|
|
|
|
init_poll_funcptr(&pt, NULL);
|
|
|
|
mutex_lock(&ep->mtx);
|
|
ep_start_scan(ep, &txlist);
|
|
|
|
/*
|
|
* We can loop without lock because we are passed a task private list.
|
|
* Items cannot vanish during the loop we are holding ep->mtx.
|
|
*/
|
|
list_for_each_entry_safe(epi, tmp, &txlist, rdllink) {
|
|
struct wakeup_source *ws;
|
|
__poll_t revents;
|
|
|
|
if (res >= maxevents)
|
|
break;
|
|
|
|
/*
|
|
* Activate ep->ws before deactivating epi->ws to prevent
|
|
* triggering auto-suspend here (in case we reactive epi->ws
|
|
* below).
|
|
*
|
|
* This could be rearranged to delay the deactivation of epi->ws
|
|
* instead, but then epi->ws would temporarily be out of sync
|
|
* with ep_is_linked().
|
|
*/
|
|
ws = ep_wakeup_source(epi);
|
|
if (ws) {
|
|
if (ws->active)
|
|
__pm_stay_awake(ep->ws);
|
|
__pm_relax(ws);
|
|
}
|
|
|
|
list_del_init(&epi->rdllink);
|
|
|
|
/*
|
|
* If the event mask intersect the caller-requested one,
|
|
* deliver the event to userspace. Again, we are holding ep->mtx,
|
|
* so no operations coming from userspace can change the item.
|
|
*/
|
|
revents = ep_item_poll(epi, &pt, 1);
|
|
if (!revents)
|
|
continue;
|
|
|
|
events = epoll_put_uevent(revents, epi->event.data, events);
|
|
if (!events) {
|
|
list_add(&epi->rdllink, &txlist);
|
|
ep_pm_stay_awake(epi);
|
|
if (!res)
|
|
res = -EFAULT;
|
|
break;
|
|
}
|
|
res++;
|
|
if (epi->event.events & EPOLLONESHOT)
|
|
epi->event.events &= EP_PRIVATE_BITS;
|
|
else if (!(epi->event.events & EPOLLET)) {
|
|
/*
|
|
* If this file has been added with Level
|
|
* Trigger mode, we need to insert back inside
|
|
* the ready list, so that the next call to
|
|
* epoll_wait() will check again the events
|
|
* availability. At this point, no one can insert
|
|
* into ep->rdllist besides us. The epoll_ctl()
|
|
* callers are locked out by
|
|
* ep_send_events() holding "mtx" and the
|
|
* poll callback will queue them in ep->ovflist.
|
|
*/
|
|
list_add_tail(&epi->rdllink, &ep->rdllist);
|
|
ep_pm_stay_awake(epi);
|
|
}
|
|
}
|
|
ep_done_scan(ep, &txlist);
|
|
mutex_unlock(&ep->mtx);
|
|
|
|
return res;
|
|
}
|
|
|
|
static struct timespec64 *ep_timeout_to_timespec(struct timespec64 *to, long ms)
|
|
{
|
|
struct timespec64 now;
|
|
|
|
if (ms < 0)
|
|
return NULL;
|
|
|
|
if (!ms) {
|
|
to->tv_sec = 0;
|
|
to->tv_nsec = 0;
|
|
return to;
|
|
}
|
|
|
|
to->tv_sec = ms / MSEC_PER_SEC;
|
|
to->tv_nsec = NSEC_PER_MSEC * (ms % MSEC_PER_SEC);
|
|
|
|
ktime_get_ts64(&now);
|
|
*to = timespec64_add_safe(now, *to);
|
|
return to;
|
|
}
|
|
|
|
/*
|
|
* autoremove_wake_function, but remove even on failure to wake up, because we
|
|
* know that default_wake_function/ttwu will only fail if the thread is already
|
|
* woken, and in that case the ep_poll loop will remove the entry anyways, not
|
|
* try to reuse it.
|
|
*/
|
|
static int ep_autoremove_wake_function(struct wait_queue_entry *wq_entry,
|
|
unsigned int mode, int sync, void *key)
|
|
{
|
|
int ret = default_wake_function(wq_entry, mode, sync, key);
|
|
|
|
/*
|
|
* Pairs with list_empty_careful in ep_poll, and ensures future loop
|
|
* iterations see the cause of this wakeup.
|
|
*/
|
|
list_del_init_careful(&wq_entry->entry);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* ep_poll - Retrieves ready events, and delivers them to the caller-supplied
|
|
* event buffer.
|
|
*
|
|
* @ep: Pointer to the eventpoll context.
|
|
* @events: Pointer to the userspace buffer where the ready events should be
|
|
* stored.
|
|
* @maxevents: Size (in terms of number of events) of the caller event buffer.
|
|
* @timeout: Maximum timeout for the ready events fetch operation, in
|
|
* timespec. If the timeout is zero, the function will not block,
|
|
* while if the @timeout ptr is NULL, the function will block
|
|
* until at least one event has been retrieved (or an error
|
|
* occurred).
|
|
*
|
|
* Return: the number of ready events which have been fetched, or an
|
|
* error code, in case of error.
|
|
*/
|
|
static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
|
|
int maxevents, struct timespec64 *timeout)
|
|
{
|
|
int res, eavail, timed_out = 0;
|
|
u64 slack = 0;
|
|
wait_queue_entry_t wait;
|
|
ktime_t expires, *to = NULL;
|
|
|
|
lockdep_assert_irqs_enabled();
|
|
|
|
if (timeout && (timeout->tv_sec | timeout->tv_nsec)) {
|
|
slack = select_estimate_accuracy(timeout);
|
|
to = &expires;
|
|
*to = timespec64_to_ktime(*timeout);
|
|
} else if (timeout) {
|
|
/*
|
|
* Avoid the unnecessary trip to the wait queue loop, if the
|
|
* caller specified a non blocking operation.
|
|
*/
|
|
timed_out = 1;
|
|
}
|
|
|
|
/*
|
|
* This call is racy: We may or may not see events that are being added
|
|
* to the ready list under the lock (e.g., in IRQ callbacks). For cases
|
|
* with a non-zero timeout, this thread will check the ready list under
|
|
* lock and will add to the wait queue. For cases with a zero
|
|
* timeout, the user by definition should not care and will have to
|
|
* recheck again.
|
|
*/
|
|
eavail = ep_events_available(ep);
|
|
|
|
while (1) {
|
|
if (eavail) {
|
|
/*
|
|
* Try to transfer events to user space. In case we get
|
|
* 0 events and there's still timeout left over, we go
|
|
* trying again in search of more luck.
|
|
*/
|
|
res = ep_send_events(ep, events, maxevents);
|
|
if (res)
|
|
return res;
|
|
}
|
|
|
|
if (timed_out)
|
|
return 0;
|
|
|
|
eavail = ep_busy_loop(ep, timed_out);
|
|
if (eavail)
|
|
continue;
|
|
|
|
if (signal_pending(current))
|
|
return -EINTR;
|
|
|
|
/*
|
|
* Internally init_wait() uses autoremove_wake_function(),
|
|
* thus wait entry is removed from the wait queue on each
|
|
* wakeup. Why it is important? In case of several waiters
|
|
* each new wakeup will hit the next waiter, giving it the
|
|
* chance to harvest new event. Otherwise wakeup can be
|
|
* lost. This is also good performance-wise, because on
|
|
* normal wakeup path no need to call __remove_wait_queue()
|
|
* explicitly, thus ep->lock is not taken, which halts the
|
|
* event delivery.
|
|
*
|
|
* In fact, we now use an even more aggressive function that
|
|
* unconditionally removes, because we don't reuse the wait
|
|
* entry between loop iterations. This lets us also avoid the
|
|
* performance issue if a process is killed, causing all of its
|
|
* threads to wake up without being removed normally.
|
|
*/
|
|
init_wait(&wait);
|
|
wait.func = ep_autoremove_wake_function;
|
|
|
|
write_lock_irq(&ep->lock);
|
|
/*
|
|
* Barrierless variant, waitqueue_active() is called under
|
|
* the same lock on wakeup ep_poll_callback() side, so it
|
|
* is safe to avoid an explicit barrier.
|
|
*/
|
|
__set_current_state(TASK_INTERRUPTIBLE);
|
|
|
|
/*
|
|
* Do the final check under the lock. ep_start/done_scan()
|
|
* plays with two lists (->rdllist and ->ovflist) and there
|
|
* is always a race when both lists are empty for short
|
|
* period of time although events are pending, so lock is
|
|
* important.
|
|
*/
|
|
eavail = ep_events_available(ep);
|
|
if (!eavail)
|
|
__add_wait_queue_exclusive(&ep->wq, &wait);
|
|
|
|
write_unlock_irq(&ep->lock);
|
|
|
|
if (!eavail)
|
|
timed_out = !schedule_hrtimeout_range(to, slack,
|
|
HRTIMER_MODE_ABS);
|
|
__set_current_state(TASK_RUNNING);
|
|
|
|
/*
|
|
* We were woken up, thus go and try to harvest some events.
|
|
* If timed out and still on the wait queue, recheck eavail
|
|
* carefully under lock, below.
|
|
*/
|
|
eavail = 1;
|
|
|
|
if (!list_empty_careful(&wait.entry)) {
|
|
write_lock_irq(&ep->lock);
|
|
/*
|
|
* If the thread timed out and is not on the wait queue,
|
|
* it means that the thread was woken up after its
|
|
* timeout expired before it could reacquire the lock.
|
|
* Thus, when wait.entry is empty, it needs to harvest
|
|
* events.
|
|
*/
|
|
if (timed_out)
|
|
eavail = list_empty(&wait.entry);
|
|
__remove_wait_queue(&ep->wq, &wait);
|
|
write_unlock_irq(&ep->lock);
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* ep_loop_check_proc - verify that adding an epoll file inside another
|
|
* epoll structure does not violate the constraints, in
|
|
* terms of closed loops, or too deep chains (which can
|
|
* result in excessive stack usage).
|
|
*
|
|
* @ep: the &struct eventpoll to be currently checked.
|
|
* @depth: Current depth of the path being checked.
|
|
*
|
|
* Return: %zero if adding the epoll @file inside current epoll
|
|
* structure @ep does not violate the constraints, or %-1 otherwise.
|
|
*/
|
|
static int ep_loop_check_proc(struct eventpoll *ep, int depth)
|
|
{
|
|
int error = 0;
|
|
struct rb_node *rbp;
|
|
struct epitem *epi;
|
|
|
|
mutex_lock_nested(&ep->mtx, depth + 1);
|
|
ep->gen = loop_check_gen;
|
|
for (rbp = rb_first_cached(&ep->rbr); rbp; rbp = rb_next(rbp)) {
|
|
epi = rb_entry(rbp, struct epitem, rbn);
|
|
if (unlikely(is_file_epoll(epi->ffd.file))) {
|
|
struct eventpoll *ep_tovisit;
|
|
ep_tovisit = epi->ffd.file->private_data;
|
|
if (ep_tovisit->gen == loop_check_gen)
|
|
continue;
|
|
if (ep_tovisit == inserting_into || depth > EP_MAX_NESTS)
|
|
error = -1;
|
|
else
|
|
error = ep_loop_check_proc(ep_tovisit, depth + 1);
|
|
if (error != 0)
|
|
break;
|
|
} else {
|
|
/*
|
|
* If we've reached a file that is not associated with
|
|
* an ep, then we need to check if the newly added
|
|
* links are going to add too many wakeup paths. We do
|
|
* this by adding it to the tfile_check_list, if it's
|
|
* not already there, and calling reverse_path_check()
|
|
* during ep_insert().
|
|
*/
|
|
list_file(epi->ffd.file);
|
|
}
|
|
}
|
|
mutex_unlock(&ep->mtx);
|
|
|
|
return error;
|
|
}
|
|
|
|
/**
|
|
* ep_loop_check - Performs a check to verify that adding an epoll file (@to)
|
|
* into another epoll file (represented by @ep) does not create
|
|
* closed loops or too deep chains.
|
|
*
|
|
* @ep: Pointer to the epoll we are inserting into.
|
|
* @to: Pointer to the epoll to be inserted.
|
|
*
|
|
* Return: %zero if adding the epoll @to inside the epoll @from
|
|
* does not violate the constraints, or %-1 otherwise.
|
|
*/
|
|
static int ep_loop_check(struct eventpoll *ep, struct eventpoll *to)
|
|
{
|
|
inserting_into = ep;
|
|
return ep_loop_check_proc(to, 0);
|
|
}
|
|
|
|
static void clear_tfile_check_list(void)
|
|
{
|
|
rcu_read_lock();
|
|
while (tfile_check_list != EP_UNACTIVE_PTR) {
|
|
struct epitems_head *head = tfile_check_list;
|
|
tfile_check_list = head->next;
|
|
unlist_file(head);
|
|
}
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
/*
|
|
* Open an eventpoll file descriptor.
|
|
*/
|
|
static int do_epoll_create(int flags)
|
|
{
|
|
int error, fd;
|
|
struct eventpoll *ep = NULL;
|
|
struct file *file;
|
|
|
|
/* Check the EPOLL_* constant for consistency. */
|
|
BUILD_BUG_ON(EPOLL_CLOEXEC != O_CLOEXEC);
|
|
|
|
if (flags & ~EPOLL_CLOEXEC)
|
|
return -EINVAL;
|
|
/*
|
|
* Create the internal data structure ("struct eventpoll").
|
|
*/
|
|
error = ep_alloc(&ep);
|
|
if (error < 0)
|
|
return error;
|
|
/*
|
|
* Creates all the items needed to setup an eventpoll file. That is,
|
|
* a file structure and a free file descriptor.
|
|
*/
|
|
fd = get_unused_fd_flags(O_RDWR | (flags & O_CLOEXEC));
|
|
if (fd < 0) {
|
|
error = fd;
|
|
goto out_free_ep;
|
|
}
|
|
file = anon_inode_getfile("[eventpoll]", &eventpoll_fops, ep,
|
|
O_RDWR | (flags & O_CLOEXEC));
|
|
if (IS_ERR(file)) {
|
|
error = PTR_ERR(file);
|
|
goto out_free_fd;
|
|
}
|
|
#ifdef CONFIG_NET_RX_BUSY_POLL
|
|
ep->busy_poll_usecs = 0;
|
|
ep->busy_poll_budget = 0;
|
|
ep->prefer_busy_poll = false;
|
|
#endif
|
|
ep->file = file;
|
|
fd_install(fd, file);
|
|
return fd;
|
|
|
|
out_free_fd:
|
|
put_unused_fd(fd);
|
|
out_free_ep:
|
|
ep_clear_and_put(ep);
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE1(epoll_create1, int, flags)
|
|
{
|
|
return do_epoll_create(flags);
|
|
}
|
|
|
|
SYSCALL_DEFINE1(epoll_create, int, size)
|
|
{
|
|
if (size <= 0)
|
|
return -EINVAL;
|
|
|
|
return do_epoll_create(0);
|
|
}
|
|
|
|
#ifdef CONFIG_PM_SLEEP
|
|
static inline void ep_take_care_of_epollwakeup(struct epoll_event *epev)
|
|
{
|
|
if ((epev->events & EPOLLWAKEUP) && !capable(CAP_BLOCK_SUSPEND))
|
|
epev->events &= ~EPOLLWAKEUP;
|
|
}
|
|
#else
|
|
static inline void ep_take_care_of_epollwakeup(struct epoll_event *epev)
|
|
{
|
|
epev->events &= ~EPOLLWAKEUP;
|
|
}
|
|
#endif
|
|
|
|
static inline int epoll_mutex_lock(struct mutex *mutex, int depth,
|
|
bool nonblock)
|
|
{
|
|
if (!nonblock) {
|
|
mutex_lock_nested(mutex, depth);
|
|
return 0;
|
|
}
|
|
if (mutex_trylock(mutex))
|
|
return 0;
|
|
return -EAGAIN;
|
|
}
|
|
|
|
int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds,
|
|
bool nonblock)
|
|
{
|
|
int error;
|
|
int full_check = 0;
|
|
struct fd f, tf;
|
|
struct eventpoll *ep;
|
|
struct epitem *epi;
|
|
struct eventpoll *tep = NULL;
|
|
|
|
error = -EBADF;
|
|
f = fdget(epfd);
|
|
if (!f.file)
|
|
goto error_return;
|
|
|
|
/* Get the "struct file *" for the target file */
|
|
tf = fdget(fd);
|
|
if (!tf.file)
|
|
goto error_fput;
|
|
|
|
/* The target file descriptor must support poll */
|
|
error = -EPERM;
|
|
if (!file_can_poll(tf.file))
|
|
goto error_tgt_fput;
|
|
|
|
/* Check if EPOLLWAKEUP is allowed */
|
|
if (ep_op_has_event(op))
|
|
ep_take_care_of_epollwakeup(epds);
|
|
|
|
/*
|
|
* We have to check that the file structure underneath the file descriptor
|
|
* the user passed to us _is_ an eventpoll file. And also we do not permit
|
|
* adding an epoll file descriptor inside itself.
|
|
*/
|
|
error = -EINVAL;
|
|
if (f.file == tf.file || !is_file_epoll(f.file))
|
|
goto error_tgt_fput;
|
|
|
|
/*
|
|
* epoll adds to the wakeup queue at EPOLL_CTL_ADD time only,
|
|
* so EPOLLEXCLUSIVE is not allowed for a EPOLL_CTL_MOD operation.
|
|
* Also, we do not currently supported nested exclusive wakeups.
|
|
*/
|
|
if (ep_op_has_event(op) && (epds->events & EPOLLEXCLUSIVE)) {
|
|
if (op == EPOLL_CTL_MOD)
|
|
goto error_tgt_fput;
|
|
if (op == EPOLL_CTL_ADD && (is_file_epoll(tf.file) ||
|
|
(epds->events & ~EPOLLEXCLUSIVE_OK_BITS)))
|
|
goto error_tgt_fput;
|
|
}
|
|
|
|
/*
|
|
* At this point it is safe to assume that the "private_data" contains
|
|
* our own data structure.
|
|
*/
|
|
ep = f.file->private_data;
|
|
|
|
/*
|
|
* When we insert an epoll file descriptor inside another epoll file
|
|
* descriptor, there is the chance of creating closed loops, which are
|
|
* better be handled here, than in more critical paths. While we are
|
|
* checking for loops we also determine the list of files reachable
|
|
* and hang them on the tfile_check_list, so we can check that we
|
|
* haven't created too many possible wakeup paths.
|
|
*
|
|
* We do not need to take the global 'epumutex' on EPOLL_CTL_ADD when
|
|
* the epoll file descriptor is attaching directly to a wakeup source,
|
|
* unless the epoll file descriptor is nested. The purpose of taking the
|
|
* 'epnested_mutex' on add is to prevent complex toplogies such as loops and
|
|
* deep wakeup paths from forming in parallel through multiple
|
|
* EPOLL_CTL_ADD operations.
|
|
*/
|
|
error = epoll_mutex_lock(&ep->mtx, 0, nonblock);
|
|
if (error)
|
|
goto error_tgt_fput;
|
|
if (op == EPOLL_CTL_ADD) {
|
|
if (READ_ONCE(f.file->f_ep) || ep->gen == loop_check_gen ||
|
|
is_file_epoll(tf.file)) {
|
|
mutex_unlock(&ep->mtx);
|
|
error = epoll_mutex_lock(&epnested_mutex, 0, nonblock);
|
|
if (error)
|
|
goto error_tgt_fput;
|
|
loop_check_gen++;
|
|
full_check = 1;
|
|
if (is_file_epoll(tf.file)) {
|
|
tep = tf.file->private_data;
|
|
error = -ELOOP;
|
|
if (ep_loop_check(ep, tep) != 0)
|
|
goto error_tgt_fput;
|
|
}
|
|
error = epoll_mutex_lock(&ep->mtx, 0, nonblock);
|
|
if (error)
|
|
goto error_tgt_fput;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Try to lookup the file inside our RB tree. Since we grabbed "mtx"
|
|
* above, we can be sure to be able to use the item looked up by
|
|
* ep_find() till we release the mutex.
|
|
*/
|
|
epi = ep_find(ep, tf.file, fd);
|
|
|
|
error = -EINVAL;
|
|
switch (op) {
|
|
case EPOLL_CTL_ADD:
|
|
if (!epi) {
|
|
epds->events |= EPOLLERR | EPOLLHUP;
|
|
error = ep_insert(ep, epds, tf.file, fd, full_check);
|
|
} else
|
|
error = -EEXIST;
|
|
break;
|
|
case EPOLL_CTL_DEL:
|
|
if (epi) {
|
|
/*
|
|
* The eventpoll itself is still alive: the refcount
|
|
* can't go to zero here.
|
|
*/
|
|
ep_remove_safe(ep, epi);
|
|
error = 0;
|
|
} else {
|
|
error = -ENOENT;
|
|
}
|
|
break;
|
|
case EPOLL_CTL_MOD:
|
|
if (epi) {
|
|
if (!(epi->event.events & EPOLLEXCLUSIVE)) {
|
|
epds->events |= EPOLLERR | EPOLLHUP;
|
|
error = ep_modify(ep, epi, epds);
|
|
}
|
|
} else
|
|
error = -ENOENT;
|
|
break;
|
|
}
|
|
mutex_unlock(&ep->mtx);
|
|
|
|
error_tgt_fput:
|
|
if (full_check) {
|
|
clear_tfile_check_list();
|
|
loop_check_gen++;
|
|
mutex_unlock(&epnested_mutex);
|
|
}
|
|
|
|
fdput(tf);
|
|
error_fput:
|
|
fdput(f);
|
|
error_return:
|
|
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* The following function implements the controller interface for
|
|
* the eventpoll file that enables the insertion/removal/change of
|
|
* file descriptors inside the interest set.
|
|
*/
|
|
SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
|
|
struct epoll_event __user *, event)
|
|
{
|
|
struct epoll_event epds;
|
|
|
|
if (ep_op_has_event(op) &&
|
|
copy_from_user(&epds, event, sizeof(struct epoll_event)))
|
|
return -EFAULT;
|
|
|
|
return do_epoll_ctl(epfd, op, fd, &epds, false);
|
|
}
|
|
|
|
/*
|
|
* Implement the event wait interface for the eventpoll file. It is the kernel
|
|
* part of the user space epoll_wait(2).
|
|
*/
|
|
static int do_epoll_wait(int epfd, struct epoll_event __user *events,
|
|
int maxevents, struct timespec64 *to)
|
|
{
|
|
int error;
|
|
struct fd f;
|
|
struct eventpoll *ep;
|
|
|
|
/* The maximum number of event must be greater than zero */
|
|
if (maxevents <= 0 || maxevents > EP_MAX_EVENTS)
|
|
return -EINVAL;
|
|
|
|
/* Verify that the area passed by the user is writeable */
|
|
if (!access_ok(events, maxevents * sizeof(struct epoll_event)))
|
|
return -EFAULT;
|
|
|
|
/* Get the "struct file *" for the eventpoll file */
|
|
f = fdget(epfd);
|
|
if (!f.file)
|
|
return -EBADF;
|
|
|
|
/*
|
|
* We have to check that the file structure underneath the fd
|
|
* the user passed to us _is_ an eventpoll file.
|
|
*/
|
|
error = -EINVAL;
|
|
if (!is_file_epoll(f.file))
|
|
goto error_fput;
|
|
|
|
/*
|
|
* At this point it is safe to assume that the "private_data" contains
|
|
* our own data structure.
|
|
*/
|
|
ep = f.file->private_data;
|
|
|
|
/* Time to fish for events ... */
|
|
error = ep_poll(ep, events, maxevents, to);
|
|
|
|
error_fput:
|
|
fdput(f);
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE4(epoll_wait, int, epfd, struct epoll_event __user *, events,
|
|
int, maxevents, int, timeout)
|
|
{
|
|
struct timespec64 to;
|
|
|
|
return do_epoll_wait(epfd, events, maxevents,
|
|
ep_timeout_to_timespec(&to, timeout));
|
|
}
|
|
|
|
/*
|
|
* Implement the event wait interface for the eventpoll file. It is the kernel
|
|
* part of the user space epoll_pwait(2).
|
|
*/
|
|
static int do_epoll_pwait(int epfd, struct epoll_event __user *events,
|
|
int maxevents, struct timespec64 *to,
|
|
const sigset_t __user *sigmask, size_t sigsetsize)
|
|
{
|
|
int error;
|
|
|
|
/*
|
|
* If the caller wants a certain signal mask to be set during the wait,
|
|
* we apply it here.
|
|
*/
|
|
error = set_user_sigmask(sigmask, sigsetsize);
|
|
if (error)
|
|
return error;
|
|
|
|
error = do_epoll_wait(epfd, events, maxevents, to);
|
|
|
|
restore_saved_sigmask_unless(error == -EINTR);
|
|
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE6(epoll_pwait, int, epfd, struct epoll_event __user *, events,
|
|
int, maxevents, int, timeout, const sigset_t __user *, sigmask,
|
|
size_t, sigsetsize)
|
|
{
|
|
struct timespec64 to;
|
|
|
|
return do_epoll_pwait(epfd, events, maxevents,
|
|
ep_timeout_to_timespec(&to, timeout),
|
|
sigmask, sigsetsize);
|
|
}
|
|
|
|
SYSCALL_DEFINE6(epoll_pwait2, int, epfd, struct epoll_event __user *, events,
|
|
int, maxevents, const struct __kernel_timespec __user *, timeout,
|
|
const sigset_t __user *, sigmask, size_t, sigsetsize)
|
|
{
|
|
struct timespec64 ts, *to = NULL;
|
|
|
|
if (timeout) {
|
|
if (get_timespec64(&ts, timeout))
|
|
return -EFAULT;
|
|
to = &ts;
|
|
if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
|
|
return -EINVAL;
|
|
}
|
|
|
|
return do_epoll_pwait(epfd, events, maxevents, to,
|
|
sigmask, sigsetsize);
|
|
}
|
|
|
|
#ifdef CONFIG_COMPAT
|
|
static int do_compat_epoll_pwait(int epfd, struct epoll_event __user *events,
|
|
int maxevents, struct timespec64 *timeout,
|
|
const compat_sigset_t __user *sigmask,
|
|
compat_size_t sigsetsize)
|
|
{
|
|
long err;
|
|
|
|
/*
|
|
* If the caller wants a certain signal mask to be set during the wait,
|
|
* we apply it here.
|
|
*/
|
|
err = set_compat_user_sigmask(sigmask, sigsetsize);
|
|
if (err)
|
|
return err;
|
|
|
|
err = do_epoll_wait(epfd, events, maxevents, timeout);
|
|
|
|
restore_saved_sigmask_unless(err == -EINTR);
|
|
|
|
return err;
|
|
}
|
|
|
|
COMPAT_SYSCALL_DEFINE6(epoll_pwait, int, epfd,
|
|
struct epoll_event __user *, events,
|
|
int, maxevents, int, timeout,
|
|
const compat_sigset_t __user *, sigmask,
|
|
compat_size_t, sigsetsize)
|
|
{
|
|
struct timespec64 to;
|
|
|
|
return do_compat_epoll_pwait(epfd, events, maxevents,
|
|
ep_timeout_to_timespec(&to, timeout),
|
|
sigmask, sigsetsize);
|
|
}
|
|
|
|
COMPAT_SYSCALL_DEFINE6(epoll_pwait2, int, epfd,
|
|
struct epoll_event __user *, events,
|
|
int, maxevents,
|
|
const struct __kernel_timespec __user *, timeout,
|
|
const compat_sigset_t __user *, sigmask,
|
|
compat_size_t, sigsetsize)
|
|
{
|
|
struct timespec64 ts, *to = NULL;
|
|
|
|
if (timeout) {
|
|
if (get_timespec64(&ts, timeout))
|
|
return -EFAULT;
|
|
to = &ts;
|
|
if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
|
|
return -EINVAL;
|
|
}
|
|
|
|
return do_compat_epoll_pwait(epfd, events, maxevents, to,
|
|
sigmask, sigsetsize);
|
|
}
|
|
|
|
#endif
|
|
|
|
static int __init eventpoll_init(void)
|
|
{
|
|
struct sysinfo si;
|
|
|
|
si_meminfo(&si);
|
|
/*
|
|
* Allows top 4% of lomem to be allocated for epoll watches (per user).
|
|
*/
|
|
max_user_watches = (((si.totalram - si.totalhigh) / 25) << PAGE_SHIFT) /
|
|
EP_ITEM_COST;
|
|
BUG_ON(max_user_watches < 0);
|
|
|
|
/*
|
|
* We can have many thousands of epitems, so prevent this from
|
|
* using an extra cache line on 64-bit (and smaller) CPUs
|
|
*/
|
|
BUILD_BUG_ON(sizeof(void *) <= 8 && sizeof(struct epitem) > 128);
|
|
|
|
/* Allocates slab cache used to allocate "struct epitem" items */
|
|
epi_cache = kmem_cache_create("eventpoll_epi", sizeof(struct epitem),
|
|
0, SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, NULL);
|
|
|
|
/* Allocates slab cache used to allocate "struct eppoll_entry" */
|
|
pwq_cache = kmem_cache_create("eventpoll_pwq",
|
|
sizeof(struct eppoll_entry), 0, SLAB_PANIC|SLAB_ACCOUNT, NULL);
|
|
epoll_sysctls_init();
|
|
|
|
ephead_cache = kmem_cache_create("ep_head",
|
|
sizeof(struct epitems_head), 0, SLAB_PANIC|SLAB_ACCOUNT, NULL);
|
|
|
|
return 0;
|
|
}
|
|
fs_initcall(eventpoll_init);
|