[PATCH] staging: rtl8192e: Exclude scan_mutex in rtllib_softmac_stop_scan
From: Philipp Hortmann
Date: Sun May 14 2023 - 16:40:48 EST
Exclude scan_mutex from cancel_delayed_work_sync(&ieee->softmac_scan_wq) as
ieee->softmac_scan_wq takes scan_mutex as well.
Signed-off-by: Philipp Hortmann <philipp.g.hortmann@xxxxxxxxx>
---
Tested with rtl8192e (WLL6130-D99)
Transferred this patch over wlan connection of rtl8192e
[ 1766.998408] ======================================================
[ 1766.998410] WARNING: possible circular locking dependency detected
[ 1766.998411] 6.3.0+ #8 Tainted: G C OE
[ 1766.998413] ------------------------------------------------------
[ 1766.998414] wpa_supplicant/1184 is trying to acquire lock:
[ 1766.998416] ffff91e404469ec8 ((work_completion)(&(&ieee->softmac_scan_wq)->work)){+.+.}-{0:0}, at: __flush_work+0x4d/0x490
[ 1766.998425]
but task is already holding lock:
[ 1766.998426] ffff91e404469150 (&ieee->scan_mutex){+.+.}-{4:4}, at: rtllib_softmac_stop_scan+0x20/0x80 [rtllib]
[ 1766.998439]
which lock already depends on the new lock.
[ 1766.998440]
the existing dependency chain (in reverse order) is:
[ 1766.998442]
-> #1 (&ieee->scan_mutex){+.+.}-{4:4}:
[ 1766.998445] __mutex_lock+0x99/0xce0
[ 1766.998450] mutex_lock_nested+0x1b/0x30
[ 1766.998453] rtllib_softmac_scan_wq+0x62/0x1e0 [rtllib]
[ 1766.998461] process_one_work+0x2ba/0x5a0
[ 1766.998463] worker_thread+0x4d/0x3d0
[ 1766.998465] kthread+0x116/0x150
[ 1766.998469] ret_from_fork+0x2c/0x50
[ 1766.998473]
-> #0 ((work_completion)(&(&ieee->softmac_scan_wq)->work)){+.+.}-{0:0}:
[ 1766.998476] __lock_acquire+0x1494/0x1fc0
[ 1766.998479] lock_acquire+0xdc/0x2c0
[ 1766.998480] __flush_work+0x6d/0x490
[ 1766.998482] __cancel_work_timer+0x137/0x1c0
[ 1766.998485] cancel_delayed_work_sync+0x13/0x20
[ 1766.998487] rtllib_softmac_stop_scan+0x60/0x80 [rtllib]
[ 1766.998494] rtllib_stop_protocol.part.0+0x113/0x130 [rtllib]
[ 1766.998503] rtllib_stop_protocol+0x1c/0x30 [rtllib]
[ 1766.998510] rtllib_wx_set_essid+0x12a/0x150 [rtllib]
[ 1766.998519] _rtl92e_wx_set_essid+0x4e/0xa0 [r8192e_pci]
[ 1766.998527] ioctl_standard_iw_point+0x2de/0x3b0
[ 1766.998531] ioctl_standard_call+0xaa/0xe0
[ 1766.998533] wireless_process_ioctl+0x194/0x1e0
[ 1766.998535] wext_handle_ioctl+0x9e/0x100
[ 1766.998537] sock_ioctl+0x200/0x340
[ 1766.998540] __x64_sys_ioctl+0x95/0xd0
[ 1766.998543] do_syscall_64+0x3b/0x90
[ 1766.998546] entry_SYSCALL_64_after_hwframe+0x72/0xdc
[ 1766.998550]
other info that might help us debug this:
[ 1766.998551] Possible unsafe locking scenario:
[ 1766.998552] CPU0 CPU1
[ 1766.998553] ---- ----
[ 1766.998554] lock(&ieee->scan_mutex);
[ 1766.998556] lock((work_completion)(&(&ieee->softmac_scan_wq)->work));
[ 1766.998558] lock(&ieee->scan_mutex);
[ 1766.998560] lock((work_completion)(&(&ieee->softmac_scan_wq)->work));
[ 1766.998562]
*** DEADLOCK ***
[ 1766.998563] 4 locks held by wpa_supplicant/1184:
[ 1766.998565] #0: ffffffff8a14f610 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock+0x17/0x20
[ 1766.998570] #1: ffff91e40446b078 (&priv->wx_mutex){+.+.}-{4:4}, at: _rtl92e_wx_set_essid+0x38/0xa0 [r8192e_pci]
[ 1766.998580] #2: ffff91e4044690b0 (&ieee->wx_mutex){+.+.}-{4:4}, at: rtllib_wx_set_essid+0x36/0x150 [rtllib]
[ 1766.998590] #3: ffff91e404469150 (&ieee->scan_mutex){+.+.}-{4:4}, at: rtllib_softmac_stop_scan+0x20/0x80 [rtllib]
[ 1766.998601]
stack backtrace:
[ 1766.998602] CPU: 3 PID: 1184 Comm: wpa_supplicant Tainted: G C OE 6.3.0+ #8
[ 1766.998605] Hardware name: FUJITSU ESPRIMO P710/D3161-A1, BIOS V4.6.5.3 R1.16.0 for D3161-A1x 10/29/2012
[ 1766.998607] Call Trace:
[ 1766.998608] <TASK>
[ 1766.998610] dump_stack_lvl+0x5c/0xa0
[ 1766.998614] dump_stack+0x10/0x20
[ 1766.998617] print_circular_bug.isra.0+0x2e5/0x420
[ 1766.998620] check_noncircular+0x103/0x120
[ 1766.998622] ? register_lock_class+0x4c/0x450
[ 1766.998624] ? check_path.constprop.0+0x28/0x50
[ 1766.998628] ? check_noncircular+0x80/0x120
[ 1766.998631] __lock_acquire+0x1494/0x1fc0
[ 1766.998633] ? __this_cpu_preempt_check+0x13/0x20
[ 1766.998638] lock_acquire+0xdc/0x2c0
[ 1766.998640] ? __flush_work+0x4d/0x490
[ 1766.998643] ? find_held_lock+0x38/0x90
[ 1766.998646] ? lock_timer_base+0x72/0xa0
[ 1766.998648] ? __this_cpu_preempt_check+0x13/0x20
[ 1766.998651] __flush_work+0x6d/0x490
[ 1766.998653] ? __flush_work+0x4d/0x490
[ 1766.998655] ? __this_cpu_preempt_check+0x13/0x20
[ 1766.998658] ? lock_release+0x14f/0x380
[ 1766.998662] ? __cancel_work_timer+0x10d/0x1c0
[ 1766.998664] ? __this_cpu_preempt_check+0x13/0x20
[ 1766.998667] __cancel_work_timer+0x137/0x1c0
[ 1766.998671] cancel_delayed_work_sync+0x13/0x20
[ 1766.998674] rtllib_softmac_stop_scan+0x60/0x80 [rtllib]
[ 1766.998682] rtllib_stop_protocol.part.0+0x113/0x130 [rtllib]
[ 1766.998690] rtllib_stop_protocol+0x1c/0x30 [rtllib]
[ 1766.998698] rtllib_wx_set_essid+0x12a/0x150 [rtllib]
[ 1766.998707] _rtl92e_wx_set_essid+0x4e/0xa0 [r8192e_pci]
[ 1766.998715] ioctl_standard_iw_point+0x2de/0x3b0
[ 1766.998718] ? __pfx__rtl92e_wx_set_essid+0x10/0x10 [r8192e_pci]
[ 1766.998726] ioctl_standard_call+0xaa/0xe0
[ 1766.998729] ? netdev_name_node_lookup+0x65/0x90
[ 1766.998732] ? __pfx_ioctl_private_call+0x10/0x10
[ 1766.998734] ? __pfx_ioctl_standard_call+0x10/0x10
[ 1766.998737] wireless_process_ioctl+0x194/0x1e0
[ 1766.998740] wext_handle_ioctl+0x9e/0x100
[ 1766.998744] sock_ioctl+0x200/0x340
[ 1766.998748] ? syscall_enter_from_user_mode+0x21/0x60
[ 1766.998751] __x64_sys_ioctl+0x95/0xd0
[ 1766.998753] do_syscall_64+0x3b/0x90
[ 1766.998757] entry_SYSCALL_64_after_hwframe+0x72/0xdc
[ 1766.998760] RIP: 0033:0x7f4ed5f223ab
[ 1766.998763] Code: 0f 1e fa 48 8b 05 e5 7a 0d 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d b5 7a 0d 00 f7 d8 64 89 01 48
[ 1766.998765] RSP: 002b:00007ffe820546c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[ 1766.998768] RAX: ffffffffffffffda RBX: 0000000000000020 RCX: 00007f4ed5f223ab
[ 1766.998769] RDX: 00007ffe820546d0 RSI: 0000000000008b1a RDI: 0000000000000009
[ 1766.998771] RBP: 000055d229516ff0 R08: 0000000000000000 R09: 00007f4ed5ffa240
[ 1766.998772] R10: 0000000000004000 R11: 0000000000000246 R12: 00007ffe82054780
[ 1766.998774] R13: 00007ffe820546d0 R14: 0000000000000000 R15: 00007ffe820547e0
[ 1766.998778] </TASK>
---
drivers/staging/rtl8192e/rtllib_softmac.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/staging/rtl8192e/rtllib_softmac.c b/drivers/staging/rtl8192e/rtllib_softmac.c
index 18885cda60f6..cb2dd18fa14b 100644
--- a/drivers/staging/rtl8192e/rtllib_softmac.c
+++ b/drivers/staging/rtl8192e/rtllib_softmac.c
@@ -682,11 +682,11 @@ static void rtllib_softmac_stop_scan(struct rtllib_device *ieee)
if (ieee->scanning_continue == 1) {
ieee->scanning_continue = 0;
ieee->actscanning = false;
-
+ mutex_unlock(&ieee->scan_mutex);
cancel_delayed_work_sync(&ieee->softmac_scan_wq);
+ } else {
+ mutex_unlock(&ieee->scan_mutex);
}
-
- mutex_unlock(&ieee->scan_mutex);
}
void rtllib_stop_scan(struct rtllib_device *ieee)
--
2.40.1