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Ido Schimmel 6aff7cbfe7 netdevsim: Block until all devices are released
Like other buses, devices on the netdevsim bus have a release callback
that is invoked when the reference count of the device drops to zero.
However, unlike other buses such as PCI, the release callback is not
necessarily built into the kernel, as netdevsim can be built as a
module.

The above is problematic as nothing prevents the module from being
unloaded before the release callback has been invoked, which can happen
asynchronously. One such example can be found in commit a380687200
("devlink: take device reference for devlink object") where devlink
calls put_device() from an RCU callback.

The issue is not theoretical and the reproducer in [1] can reliably
crash the kernel. The conclusion of this discussion was that the issue
should be solved in netdevsim, which is what this patch is trying to do.

Add a reference count that is increased when a device is added to the
bus and decreased when a device is released. Signal a completion when
the reference count drops to zero and wait for the completion when
unloading the module so that the module will not be unloaded before all
the devices were released. The reference count is initialized to one so
that completion is only signaled when unloading the module.

With this patch, the reproducer in [1] no longer crashes the kernel.

[1] https://lore.kernel.org/netdev/20230619125015.1541143-2-idosch@nvidia.com/

Fixes: a380687200 ("devlink: take device reference for devlink object")
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20231026083343.890689-1-idosch@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-10-27 14:48:36 -07:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-10-26 13:46:28 -07:00
block block: Fix regression in sed-opal for a saved key. 2023-10-13 08:16:08 -06:00
certs certs: Reference revocation list for all keyrings 2023-08-17 20:12:41 +00:00
crypto KEYS: asymmetric: Fix sign/verify on pkcs1pad without a hash 2023-10-18 12:27:10 +08:00
Documentation Documentation/tcp: Add TCP-AO documentation 2023-10-27 10:35:46 +01:00
drivers netdevsim: Block until all devices are released 2023-10-27 14:48:36 -07:00
fs fix for lock_rename() misuse in nfsd 2023-10-23 20:40:04 -10:00
include net: Add MDB get device operation 2023-10-27 10:51:41 +01:00
init workqueue: Changes for v6.6 2023-09-01 16:06:32 -07:00
io_uring io_uring: fix crash with IORING_SETUP_NO_MMAP and invalid SQ ring address 2023-10-18 09:22:14 -06:00
ipc Add x86 shadow stack support 2023-08-31 12:20:12 -07:00
kernel bpf-next-for-netdev 2023-10-26 20:02:41 -07:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-10-26 13:46:28 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm bpf-next-for-netdev 2023-10-26 20:02:41 -07:00
net af_unix: Remove module remnants. 2023-10-27 09:12:47 -07:00
rust rust: docs: fix logo replacement 2023-10-19 16:40:00 +02:00
samples samples/bpf: Allow building with custom bpftool 2023-10-26 15:32:13 +02:00
scripts kbuild: remove stale code for 'source' symlink in packaging scripts 2023-10-01 23:06:06 +09:00
security KEYS: trusted: Remove redundant static calls usage 2023-10-10 11:19:43 -07:00
sound sound fixes for 6.6-rc7 2023-10-20 10:05:10 -07:00
tools selftests: mptcp: display simult in extra_msg 2023-10-27 08:47:30 -07:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt ARM: 2023-09-07 13:52:20 -07:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: rpm-pkg: rename binkernel.spec to kernel.spec 2023-07-25 00:59:33 +09:00
.mailmap 20 hotfixes. 12 are cc:stable and the remainder address post-6.5 issues 2023-10-24 09:52:16 -10:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS USB: Remove Wireless USB and UWB documentation 2023-08-09 14:17:32 +02:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: Remove linuxwwan@intel.com mailing list 2023-10-26 22:20:58 -07:00
Makefile Linux 6.6-rc7 2023-10-22 12:11:21 -10:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.