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Hans de Goede 12cfdef56c staging: rtl8723bs: remove a second possible deadlock 
[ Upstream commit a7ac783c33 ]

Lockdep complains about rtw_free_assoc_resources() taking the sta_hash_lock
followed by it calling rtw_free_stainfo() which takes xmitpriv->lock.
While the rtl8723bs_xmit_thread takes the sta_hash_lock while already
holding the xmitpriv->lock:

[  103.849756] ======================================================
[  103.849761] WARNING: possible circular locking dependency detected
[  103.849767] 5.15.0-rc1+ #470 Tainted: G         C  E
[  103.849773] ------------------------------------------------------
[  103.849776] wpa_supplicant/695 is trying to acquire lock:
[  103.849781] ffffa5d0c0562b00 (&pxmitpriv->lock){+.-.}-{2:2}, at: rtw_free_stainfo+0x8a/0x510 [r8723bs]
[  103.849840]
               but task is already holding lock:
[  103.849843] ffffa5d0c05636a8 (&pstapriv->sta_hash_lock){+.-.}-{2:2}, at: rtw_free_assoc_resources+0x48/0x110 [r8723bs]
[  103.849881]
               which lock already depends on the new lock.

[  103.849884]
               the existing dependency chain (in reverse order) is:
[  103.849887]
               -> #1 (&pstapriv->sta_hash_lock){+.-.}-{2:2}:
[  103.849898]        _raw_spin_lock_bh+0x34/0x40
[  103.849913]        rtw_get_stainfo+0x93/0x110 [r8723bs]
[  103.849948]        rtw_make_wlanhdr+0x14a/0x270 [r8723bs]
[  103.849983]        rtw_xmitframe_coalesce+0x5c/0x6c0 [r8723bs]
[  103.850019]        rtl8723bs_xmit_thread+0x4ac/0x620 [r8723bs]
[  103.850050]        kthread+0x143/0x160
[  103.850058]        ret_from_fork+0x22/0x30
[  103.850067]
               -> #0 (&pxmitpriv->lock){+.-.}-{2:2}:
[  103.850077]        __lock_acquire+0x1158/0x1de0
[  103.850084]        lock_acquire+0xb5/0x2b0
[  103.850090]        _raw_spin_lock_bh+0x34/0x40
[  103.850095]        rtw_free_stainfo+0x8a/0x510 [r8723bs]
[  103.850130]        rtw_free_assoc_resources+0x53/0x110 [r8723bs]
[  103.850159]        PHY_IQCalibrate_8723B+0x122b/0x36a0 [r8723bs]
[  103.850189]        cfg80211_disconnect+0x173/0x320 [cfg80211]
[  103.850331]        nl80211_disconnect+0x6e/0xb0 [cfg80211]
[  103.850422]        genl_family_rcv_msg_doit+0xcd/0x110
[  103.850430]        genl_rcv_msg+0xce/0x1c0
[  103.850435]        netlink_rcv_skb+0x50/0xf0
[  103.850441]        genl_rcv+0x24/0x40
[  103.850446]        netlink_unicast+0x16d/0x230
[  103.850452]        netlink_sendmsg+0x22b/0x450
[  103.850457]        sock_sendmsg+0x5e/0x60
[  103.850465]        ____sys_sendmsg+0x22f/0x270
[  103.850472]        ___sys_sendmsg+0x81/0xc0
[  103.850479]        __sys_sendmsg+0x49/0x80
[  103.850485]        do_syscall_64+0x3b/0x90
[  103.850493]        entry_SYSCALL_64_after_hwframe+0x44/0xae
[  103.850500]
               other info that might help us debug this:

[  103.850504]  Possible unsafe locking scenario:

[  103.850507]        CPU0                    CPU1
[  103.850510]        ----                    ----
[  103.850512]   lock(&pstapriv->sta_hash_lock);
[  103.850518]                                lock(&pxmitpriv->lock);
[  103.850524]                                lock(&pstapriv->sta_hash_lock);
[  103.850530]   lock(&pxmitpriv->lock);
[  103.850535]
                *** DEADLOCK ***

Push the taking of sta_hash_lock down into rtw_free_stainfo(),
where the critical section is, this allows taking the lock after
rtw_free_stainfo() has released pxmitpriv->lock.

This requires changing rtw_free_all_stainfo() so that it does its freeing
in 2 steps, first moving all stainfo-s to free to a local list while
holding the sta_hash_lock and then walking that list to call
rtw_free_stainfo() on them without holding the sta_hash_lock.

Pushing the taking of sta_hash_lock down into rtw_free_stainfo(),
also fixes a whole bunch of callers of rtw_free_stainfo() which
were not holding that lock even though they should.

Note that this also fixes the deadlock from the "remove possible
deadlock when disconnect" patch in a different way. But the
changes from that patch offer a nice locking cleanup regardless.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20210920145502.155454-2-hdegoede@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-11-25 09:48:25 +01:00
arch ARM: dts: ux500: Skomer regulator fixes 2021-11-25 09:48:25 +01:00
block block: Hold invalidate_lock in BLKRESETZONE ioctl 2021-11-18 19:17:15 +01:00
certs certs: Add support for using elliptic curve keys for signing modules 2021-08-23 19:55:42 +03:00
crypto crypto: pcrypt - Delay write to padata->info 2021-11-18 19:16:44 +01:00
Documentation fscrypt: allow 256-bit master keys with AES-256-XTS 2021-11-18 19:16:11 +01:00
drivers staging: rtl8723bs: remove a second possible deadlock 2021-11-25 09:48:25 +01:00
fs btrfs: zoned: allow preallocation for relocation inodes 2021-11-21 13:44:13 +01:00
include bus: ti-sysc: Add quirk handling for reinit on context lost 2021-11-25 09:48:24 +01:00
init init: make unknown command line param message clearer 2021-11-18 19:17:11 +01:00
ipc ipc: remove memcg accounting for sops objects in do_semtimedop() 2021-09-14 10:22:11 -07:00
kernel perf/core: Avoid put_page() when GUP fails 2021-11-21 13:44:14 +01:00
lib string: uninline memcpy_and_pad 2021-11-21 13:44:12 +01:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm mm, oom: do not trigger out_of_memory from the #PF 2021-11-18 19:17:16 +01:00
net SUNRPC: Partial revert of commit 6f9f17287e 2021-11-18 19:17:20 +01:00
samples samples/kretprobes: Fix return value if register_kretprobe() failed 2021-11-18 19:16:42 +01:00
scripts leaking_addresses: Always print a trailing newline 2021-11-18 19:16:16 +01:00
security fortify: Explicitly disable Clang support 2021-11-21 13:44:13 +01:00
sound ASoC: mediatek: mt8195: Add missing of_node_put() 2021-11-25 09:48:24 +01:00
tools selftests/bpf: Fix also no-alu32 strobemeta selftest 2021-11-18 19:17:21 +01:00
usr .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
virt KVM: Remove tlbs_dirty 2021-09-23 11:01:12 -04:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: add Andrej Shadura 2021-10-18 20:22:03 -10:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
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 drm fixes for 5.15 final 2021-10-28 12:17:01 -07:00
Makefile Linux 5.15.4 2021-11-21 13:44:15 +01:00
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.