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f45cb6b29c
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Wen Gong f45cb6b29c wifi: ath11k: avoid deadlock during regulatory update in ath11k_regd_update() 
(cherry picked from commit d99884ad9e in ath-next
as users are seeing this bug more now, also cc stable)

Running this test in a loop it is easy to reproduce an rtnl deadlock:

iw reg set FI
ifconfig wlan0 down

What happens is that thread A (workqueue) tries to update the regulatory:

    try to acquire the rtnl_lock of ar->regd_update_work

    rtnl_lock+0x17/0x20
    ath11k_regd_update+0x15a/0x260 [ath11k]
    ath11k_regd_update_work+0x15/0x20 [ath11k]
    process_one_work+0x228/0x670
    worker_thread+0x4d/0x440
    kthread+0x16d/0x1b0
    ret_from_fork+0x22/0x30

And thread B (ifconfig) tries to stop the interface:

    try to cancel_work_sync(&ar->regd_update_work) in ath11k_mac_op_stop().
    ifconfig  3109 [003]  2414.232506: probe:

    ath11k_mac_op_stop: (ffffffffc14187a0)
    drv_stop+0x30 ([mac80211])
    ieee80211_do_stop+0x5d2 ([mac80211])
    ieee80211_stop+0x3e ([mac80211])
    __dev_close_many+0x9e ([kernel.kallsyms])
    __dev_change_flags+0xbe ([kernel.kallsyms])
    dev_change_flags+0x23 ([kernel.kallsyms])
    devinet_ioctl+0x5e3 ([kernel.kallsyms])
    inet_ioctl+0x197 ([kernel.kallsyms])
    sock_do_ioctl+0x4d ([kernel.kallsyms])
    sock_ioctl+0x264 ([kernel.kallsyms])
    __x64_sys_ioctl+0x92 ([kernel.kallsyms])
    do_syscall_64+0x3a ([kernel.kallsyms])
    entry_SYSCALL_64_after_hwframe+0x63 ([kernel.kallsyms])
    __GI___ioctl+0x7 (/lib/x86_64-linux-gnu/libc-2.23.so)

The sequence of deadlock is:

1. Thread B calls rtnl_lock().

2. Thread A starts to run and calls rtnl_lock() from within
   ath11k_regd_update_work(), then enters wait state because the lock is owned by
   thread B.

3. Thread B continues to run and tries to call
   cancel_work_sync(&ar->regd_update_work), but thread A is in
   ath11k_regd_update_work() waiting for rtnl_lock(). So cancel_work_sync()
   forever waits for ath11k_regd_update_work() to finish and we have a deadlock.

Fix this by switching from using regulatory_set_wiphy_regd_sync() to
regulatory_set_wiphy_regd(). Now cfg80211 will schedule another workqueue which
handles the locking on it's own. So the ath11k workqueue can simply exit without
taking any locks, avoiding the deadlock.

Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3

Cc: <stable@vger.kernel.org>
Signed-off-by: Wen Gong <quic_wgong@quicinc.com>
[kvalo: improve commit log]
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
2022-11-02 19:16:45 +02:00
arch Random number generator fixes for Linux 6.1-rc1. 2022-10-16 15:27:07 -07:00
block Random number generator fixes for Linux 6.1-rc1. 2022-10-16 15:27:07 -07:00
certs certs: make system keyring depend on built-in x509 parser 2022-09-24 04:31:18 +09:00
crypto treewide: use get_random_bytes() when possible 2022-10-11 17:42:58 -06:00
Documentation Networking fixes for 6.1-rc2, including fixes from netfilter 2022-10-20 17:24:59 -07:00
drivers wifi: ath11k: avoid deadlock during regulatory update in ath11k_regd_update() 2022-11-02 19:16:45 +02:00
fs for-6.1-rc1-tag 2022-10-18 11:25:50 -07:00
include Networking fixes for 6.1-rc2, including fixes from netfilter 2022-10-20 17:24:59 -07:00
init - hfs and hfsplus kmap API modernization from Fabio Francesco 2022-10-12 11:00:22 -07:00
io_uring io_uring/rw: ensure kiocb_end_write() is always called 2022-10-12 16:30:56 -06:00
ipc - hfs and hfsplus kmap API modernization from Fabio Francesco 2022-10-12 11:00:22 -07:00
kernel cgroup fixes for v6.1-rc1 2022-10-17 18:52:43 -07:00
lib Random number generator fixes for Linux 6.1-rc1. 2022-10-16 15:27:07 -07:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm Random number generator fixes for Linux 6.1-rc1. 2022-10-16 15:27:07 -07:00
net wifi: mac80211: Set TWT Information Frame Disabled bit as 1 2022-11-02 09:50:40 +01:00
rust Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
samples VFIO updates for v6.1-rc1 2022-10-12 14:46:48 -07:00
scripts Kbuild fixes for v6.1 2022-10-16 11:12:22 -07:00
security - Yu Zhao's Multi-Gen LRU patches are here. They've been under test in 2022-10-10 17:53:04 -07:00
sound sound fixes for 6.1-rc1 2022-10-14 13:22:14 -07:00
tools Networking fixes for 6.1-rc2, including fixes from netfilter 2022-10-20 17:24:59 -07:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt VFIO updates for v6.1-rc1 2022-10-12 14:46:48 -07:00
.clang-format PCI/DOE: Add DOE mailbox support functions 2022-07-19 15:38:04 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap - hfs and hfsplus kmap API modernization from Fabio Francesco 2022-10-12 11:00:22 -07:00
.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 drm for 5.20/6.0 2022-08-03 19:52:08 -07:00
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 Networking fixes for 6.1-rc2, including fixes from netfilter 2022-10-20 17:24:59 -07:00
Makefile Linux 6.1-rc1 2022-10-16 15:36:24 -07:00
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.