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Jiri Kosina 295d4cd82b iwlwifi: don't call netif_napi_add() with rxq->lock held (was Re: Lockdep warning in iwl_pcie_rx_handle()) 
We can't call netif_napi_add() with rxq-lock held, as there is a potential
for deadlock as spotted by lockdep (see below). rxq->lock is not
protecting anything over the netif_napi_add() codepath anyway, so let's
drop it just before calling into NAPI.

 ========================================================
 WARNING: possible irq lock inversion dependency detected
 5.12.0-rc1-00002-gbada49429032 #5 Not tainted
 --------------------------------------------------------
 irq/136-iwlwifi/565 just changed the state of lock:
 ffff89f28433b0b0 (&rxq->lock){+.-.}-{2:2}, at: iwl_pcie_rx_handle+0x7f/0x960 [iwlwifi]
 but this lock took another, SOFTIRQ-unsafe lock in the past:
  (napi_hash_lock){+.+.}-{2:2}

 and interrupts could create inverse lock ordering between them.

 other info that might help us debug this:
  Possible interrupt unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(napi_hash_lock);
                                local_irq_disable();
                                lock(&rxq->lock);
                                lock(napi_hash_lock);
   <Interrupt>
     lock(&rxq->lock);

  *** DEADLOCK ***

 1 lock held by irq/136-iwlwifi/565:
  #0: ffff89f2b1440170 (sync_cmd_lockdep_map){+.+.}-{0:0}, at: iwl_pcie_irq_handler+0x5/0xb30

 the shortest dependencies between 2nd lock and 1st lock:
  -> (napi_hash_lock){+.+.}-{2:2} {
     HARDIRQ-ON-W at:
                       lock_acquire+0x277/0x3d0
                       _raw_spin_lock+0x2c/0x40
                       netif_napi_add+0x14b/0x270
                       e1000_probe+0x2fe/0xee0 [e1000e]
                       local_pci_probe+0x42/0x90
                       pci_device_probe+0x10b/0x1c0
                       really_probe+0xef/0x4b0
                       driver_probe_device+0xde/0x150
                       device_driver_attach+0x4f/0x60
                       __driver_attach+0x9c/0x140
                       bus_for_each_dev+0x79/0xc0
                       bus_add_driver+0x18d/0x220
                       driver_register+0x5b/0xf0
                       do_one_initcall+0x5b/0x300
                       do_init_module+0x5b/0x21c
                       load_module+0x1dae/0x22c0
                       __do_sys_finit_module+0xad/0x110
                       do_syscall_64+0x33/0x80
                       entry_SYSCALL_64_after_hwframe+0x44/0xae
     SOFTIRQ-ON-W at:
                       lock_acquire+0x277/0x3d0
                       _raw_spin_lock+0x2c/0x40
                       netif_napi_add+0x14b/0x270
                       e1000_probe+0x2fe/0xee0 [e1000e]
                       local_pci_probe+0x42/0x90
                       pci_device_probe+0x10b/0x1c0
                       really_probe+0xef/0x4b0
                       driver_probe_device+0xde/0x150
                       device_driver_attach+0x4f/0x60
                       __driver_attach+0x9c/0x140
                       bus_for_each_dev+0x79/0xc0
                       bus_add_driver+0x18d/0x220
                       driver_register+0x5b/0xf0
                       do_one_initcall+0x5b/0x300
                       do_init_module+0x5b/0x21c
                       load_module+0x1dae/0x22c0
                       __do_sys_finit_module+0xad/0x110
                       do_syscall_64+0x33/0x80
                       entry_SYSCALL_64_after_hwframe+0x44/0xae
     INITIAL USE at:
                      lock_acquire+0x277/0x3d0
                      _raw_spin_lock+0x2c/0x40
                      netif_napi_add+0x14b/0x270
                      e1000_probe+0x2fe/0xee0 [e1000e]
                      local_pci_probe+0x42/0x90
                      pci_device_probe+0x10b/0x1c0
                      really_probe+0xef/0x4b0
                      driver_probe_device+0xde/0x150
                      device_driver_attach+0x4f/0x60
                      __driver_attach+0x9c/0x140
                      bus_for_each_dev+0x79/0xc0
                      bus_add_driver+0x18d/0x220
                      driver_register+0x5b/0xf0
                      do_one_initcall+0x5b/0x300
                      do_init_module+0x5b/0x21c
                      load_module+0x1dae/0x22c0
                      __do_sys_finit_module+0xad/0x110
                      do_syscall_64+0x33/0x80
                      entry_SYSCALL_64_after_hwframe+0x44/0xae
   }
   ... key      at: [<ffffffffae84ef38>] napi_hash_lock+0x18/0x40
   ... acquired at:
    _raw_spin_lock+0x2c/0x40
    netif_napi_add+0x14b/0x270
    _iwl_pcie_rx_init+0x1f4/0x710 [iwlwifi]
    iwl_pcie_rx_init+0x1b/0x3b0 [iwlwifi]
    iwl_trans_pcie_start_fw+0x2ac/0x6a0 [iwlwifi]
    iwl_mvm_load_ucode_wait_alive+0x116/0x460 [iwlmvm]
    iwl_run_init_mvm_ucode+0xa4/0x3a0 [iwlmvm]
    iwl_op_mode_mvm_start+0x9ed/0xbf0 [iwlmvm]
    _iwl_op_mode_start.isra.4+0x42/0x80 [iwlwifi]
    iwl_opmode_register+0x71/0xe0 [iwlwifi]
    iwl_mvm_init+0x34/0x1000 [iwlmvm]
    do_one_initcall+0x5b/0x300
    do_init_module+0x5b/0x21c
    load_module+0x1dae/0x22c0
    __do_sys_finit_module+0xad/0x110
    do_syscall_64+0x33/0x80
    entry_SYSCALL_64_after_hwframe+0x44/0xae

[ ... lockdep output trimmed .... ]

Fixes: 25edc8f259 ("iwlwifi: pcie: properly implement NAPI")
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/nycvar.YFH.7.76.2103021134060.12405@cbobk.fhfr.pm
2021-03-03 17:59:16 +02:00
arch dts: marvell: add CM3 SRAM memory to cp11x ethernet device tree 2021-02-11 14:50:23 -08:00
block block-5.11-2021-02-05 2021-02-06 14:40:27 -08:00
certs .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
crypto X.509: Fix crash caused by NULL pointer 2021-01-20 11:33:51 -08:00
Documentation dt-bindings: net: xilinx_axienet: add xlnx,switch-x-sgmii attribute 2021-02-12 17:38:53 -08:00
drivers iwlwifi: don't call netif_napi_add() with rxq->lock held (was Re: Lockdep warning in iwl_pcie_rx_handle()) 2021-03-03 17:59:16 +02:00
fs nilfs2: make splice write available again 2021-02-10 11:19:58 -08:00
include tcp: factorize logic into tcp_epollin_ready() 2021-02-12 17:28:26 -08:00
init init/gcov: allow CONFIG_CONSTRUCTORS on UML to fix module gcov 2021-02-05 11:03:47 -08:00
ipc Merge branch 'akpm' (patches from Andrew) 2020-12-15 12:53:37 -08:00
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2021-02-10 13:30:12 -08:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2021-02-10 13:30:12 -08:00
LICENSES LICENSES: Add the CC-BY-4.0 license 2020-12-08 10:33:27 -07:00
mm Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2021-02-10 13:30:12 -08:00
net tcp: factorize logic into tcp_epollin_ready() 2021-02-12 17:28:26 -08:00
samples bpf: Rename BPF_XADD and prepare to encode other atomics in .imm 2021-01-14 18:34:29 -08:00
scripts kallsyms: fix nonconverging kallsyms table with lld 2021-02-05 17:53:28 +09:00
security cap: fix conversions on getxattr 2021-01-28 10:22:48 +01:00
sound ALSA: hda/via: Apply the workaround generically for Clevo machines 2021-01-26 18:05:03 +01:00
tools selftests: tc: Add generic mpls matching support for tc-flower 2021-02-12 17:13:52 -08:00
usr Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 13:29:39 -07:00
virt KVM/arm64 fixes for 5.11, take #2 2021-01-25 18:52:01 -05:00
.clang-format clang-format: Update with the latest for_each macro list 2021-01-29 15:00:23 +01:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
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.gitignore .gitignore: docs: ignore sphinx_*/ directories 2020-09-10 10:44:31 -06:00
.mailmap MAINTAINERS: update Andrey Ryabinin's email address 2021-02-09 17:26:44 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: dccp: move Gerrit Renker to CREDITS 2021-01-14 10:53:49 -08:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: update for mwifiex driver maintainers 2021-02-24 08:36:23 +02:00
Makefile Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2021-02-10 13:30:12 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.