[PATCH 2/4] staging: rtl8192e: Remove mutex from rtllib_softmac_free()
From: Philipp Hortmann
Date: Sun Sep 24 2023 - 15:51:07 EST
The following commands use the mutex ieee->wx_mutex:
cancel_delayed_work_sync(&ieee->associate_retry_wq)
cancel_delayed_work_sync(&ieee->associate_procedure_wq)
cancel_work_sync(&ieee->wx_sync_scan_wq)
Therefore they cannot be canceled with ieee->wx_mutex locked. As the
work functions are executed time shifted during normal operation of the
driver, proper locking can only be done inside the functions.
Signed-off-by: Philipp Hortmann <philipp.g.hortmann@xxxxxxxxx>
---
Tested with rtl8192e (WLL6130-D99) in Mode n (12.5 MB/s)
Transferred this patch over wlan connection of rtl8192e.
[ 261.339100] ======================================================
[ 261.339102] WARNING: possible circular locking dependency detected
[ 261.339103] 6.6.0-rc1+ #15 Tainted: G C OE
[ 261.339105] ------------------------------------------------------
[ 261.339106] rmmod/6566 is trying to acquire lock:
[ 261.339109] ffff888113ca8800 ((work_completion)(&(&ieee->associate_procedure_wq)->work)){+.+.}-{0:0}, at: __flush_work+0x4d/0x490
[ 261.339118]
but task is already holding lock:
[ 261.339119] ffff888113ca7aa0 (&ieee->wx_mutex){+.+.}-{4:4}, at: rtllib_softmac_free+0x20/0xd0 [rtllib]
[ 261.339134]
which lock already depends on the new lock.
[ 261.339136]
the existing dependency chain (in reverse order) is:
[ 261.339137]
-> #1 (&ieee->wx_mutex){+.+.}-{4:4}:
[ 261.339140] __mutex_lock+0x99/0xce0
[ 261.339146] mutex_lock_nested+0x1b/0x30
[ 261.339149] rtllib_associate_procedure_wq+0x5b/0x4b0 [rtllib]
[ 261.339159] process_scheduled_works+0x308/0x580
[ 261.339161] worker_thread+0x19b/0x360
[ 261.339163] kthread+0x116/0x150
[ 261.339166] ret_from_fork+0x3c/0x60
[ 261.339170] ret_from_fork_asm+0x1b/0x30
[ 261.339174]
-> #0 ((work_completion)(&(&ieee->associate_procedure_wq)->work)){+.+.}-{0:0}:
[ 261.339177] __lock_acquire+0x12e0/0x1de0
[ 261.339182] lock_acquire+0xdc/0x2c0
[ 261.339185] __flush_work+0x6d/0x490
[ 261.339187] __cancel_work_timer+0x137/0x1c0
[ 261.339190] cancel_delayed_work_sync+0x13/0x20
[ 261.339192] rtllib_softmac_free+0x5b/0xd0 [rtllib]
[ 261.339201] free_rtllib+0x27/0x70 [rtllib]
[ 261.339209] _rtl92e_pci_disconnect+0xaf/0x140 [r8192e_pci]
[ 261.339217] pci_device_remove+0x39/0xb0
[ 261.339221] device_remove+0x46/0x70
[ 261.339225] device_release_driver_internal+0xb9/0x140
[ 261.339228] driver_detach+0x4d/0xa0
[ 261.339231] bus_remove_driver+0x6e/0xf0
[ 261.339233] driver_unregister+0x31/0x50
[ 261.339236] pci_unregister_driver+0x40/0x90
[ 261.339239] rtl8192_pci_driver_exit+0x10/0x380 [r8192e_pci]
[ 261.339247] __do_sys_delete_module.isra.0+0x187/0x2f0
[ 261.339251] __x64_sys_delete_module+0x12/0x20
[ 261.339254] do_syscall_64+0x3b/0x90
[ 261.339257] entry_SYSCALL_64_after_hwframe+0x6e/0xd8
[ 261.339261]
other info that might help us debug this:
[ 261.339262] Possible unsafe locking scenario:
[ 261.339263] CPU0 CPU1
[ 261.339264] ---- ----
[ 261.339265] lock(&ieee->wx_mutex);
[ 261.339268] lock((work_completion)(&(&ieee->associate_procedure_wq)->work));
[ 261.339270] lock(&ieee->wx_mutex);
[ 261.339272] lock((work_completion)(&(&ieee->associate_procedure_wq)->work));
[ 261.339274]
*** DEADLOCK ***
[ 261.339275] 2 locks held by rmmod/6566:
[ 261.339277] #0: ffff8881015d51b0 (&dev->mutex){....}-{4:4}, at: __device_driver_lock+0x2d/0x50
[ 261.339283] #1: ffff888113ca7aa0 (&ieee->wx_mutex){+.+.}-{4:4}, at: rtllib_softmac_free+0x20/0xd0 [rtllib]
[ 261.339295]
stack backtrace:
[ 261.339296] CPU: 1 PID: 6566 Comm: rmmod Tainted: G C OE 6.6.0-rc1+ #15
[ 261.339299] Hardware name: FUJITSU ESPRIMO P710/D3161-A1, BIOS V4.6.5.3 R1.16.0 for D3161-A1x 10/29/2012
[ 261.339301] Call Trace:
[ 261.339302] <TASK>
[ 261.339304] dump_stack_lvl+0x5c/0xa0
[ 261.339309] dump_stack+0x10/0x20
[ 261.339311] print_circular_bug.isra.0+0x300/0x440
[ 261.339316] check_noncircular+0x136/0x150
[ 261.339319] ? register_lock_class+0x4c/0x460
[ 261.339322] ? __bfs+0x110/0x250
[ 261.339326] __lock_acquire+0x12e0/0x1de0
[ 261.339330] ? hugetlb_init+0x5b2/0x720
[ 261.339335] lock_acquire+0xdc/0x2c0
[ 261.339339] ? __flush_work+0x4d/0x490
[ 261.339342] ? __this_cpu_preempt_check+0x13/0x20
[ 261.339345] ? lock_release+0x14f/0x380
[ 261.339349] __flush_work+0x6d/0x490
[ 261.339352] ? __flush_work+0x4d/0x490
[ 261.339354] ? lock_timer_base+0x72/0xa0
[ 261.339357] ? __this_cpu_preempt_check+0x13/0x20
[ 261.339359] ? lock_acquired+0xef/0x3b0
[ 261.339362] ? sched_clock_noinstr+0x9/0x10
[ 261.339367] ? __cancel_work_timer+0x10d/0x1c0
[ 261.339369] ? __this_cpu_preempt_check+0x13/0x20
[ 261.339373] __cancel_work_timer+0x137/0x1c0
[ 261.339377] cancel_delayed_work_sync+0x13/0x20
[ 261.339380] rtllib_softmac_free+0x5b/0xd0 [rtllib]
[ 261.339389] free_rtllib+0x27/0x70 [rtllib]
[ 261.339397] _rtl92e_pci_disconnect+0xaf/0x140 [r8192e_pci]
[ 261.339406] pci_device_remove+0x39/0xb0
[ 261.339410] device_remove+0x46/0x70
[ 261.339413] device_release_driver_internal+0xb9/0x140
[ 261.339417] driver_detach+0x4d/0xa0
[ 261.339420] bus_remove_driver+0x6e/0xf0
[ 261.339424] driver_unregister+0x31/0x50
[ 261.339427] pci_unregister_driver+0x40/0x90
[ 261.339431] rtl8192_pci_driver_exit+0x10/0x380 [r8192e_pci]
[ 261.339439] __do_sys_delete_module.isra.0+0x187/0x2f0
[ 261.339442] ? syscall_enter_from_user_mode+0x21/0x60
[ 261.339446] ? lockdep_hardirqs_on+0x86/0x110
[ 261.339450] __x64_sys_delete_module+0x12/0x20
[ 261.339454] do_syscall_64+0x3b/0x90
[ 261.339457] entry_SYSCALL_64_after_hwframe+0x6e/0xd8
[ 261.339461] RIP: 0033:0x7f3b2132da6b
[ 261.339464] Code: 73 01 c3 48 8b 0d 25 c4 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 b0 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d f5 c3 0c 00 f7 d8 64 89 01 48
[ 261.339466] RSP: 002b:00007ffea140e858 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
[ 261.339469] RAX: ffffffffffffffda RBX: 00005637c0086770 RCX: 00007f3b2132da6b
[ 261.339471] RDX: 000000000000000a RSI: 0000000000000800 RDI: 00005637c00867d8
[ 261.339473] RBP: 00007ffea140e8b8 R08: 0000000000000000 R09: 0000000000000000
[ 261.339474] R10: 00007f3b213a9ac0 R11: 0000000000000206 R12: 00007ffea140ea90
[ 261.339476] R13: 00007ffea140f7c0 R14: 00005637c00862a0 R15: 00005637c0086770
[ 261.339480] </TASK>
---
drivers/staging/rtl8192e/rtllib_softmac.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/drivers/staging/rtl8192e/rtllib_softmac.c b/drivers/staging/rtl8192e/rtllib_softmac.c
index d3468b646ca8..c874468d075c 100644
--- a/drivers/staging/rtl8192e/rtllib_softmac.c
+++ b/drivers/staging/rtl8192e/rtllib_softmac.c
@@ -2461,7 +2461,6 @@ int rtllib_softmac_init(struct rtllib_device *ieee)
void rtllib_softmac_free(struct rtllib_device *ieee)
{
- mutex_lock(&ieee->wx_mutex);
del_timer_sync(&ieee->associate_timer);
cancel_delayed_work_sync(&ieee->associate_retry_wq);
@@ -2477,7 +2476,6 @@ void rtllib_softmac_free(struct rtllib_device *ieee)
kfree(ieee->dot11d_info);
ieee->dot11d_info = NULL;
- mutex_unlock(&ieee->wx_mutex);
}
static inline struct sk_buff *
--
2.42.0