From 215792eda008f6a1e7ed9d77fa20d582d22bb114 Mon Sep 17 00:00:00 2001
From: Hans de Goede <hdegoede@redhat.com>
Date: Tue, 21 Feb 2023 15:53:23 +0100
Subject: [PATCH] drivers: staging: rtl8723bs: Fix locking in _rtw_join_timeout_handler()
Git-commit: 215792eda008f6a1e7ed9d77fa20d582d22bb114
Patch-mainline: v6.4-rc1
References: git-fixes

Commit 041879b12ddb ("drivers: staging: rtl8192bs: Fix deadlock in
rtw_joinbss_event_prehandle()") besides fixing the deadlock also
modified _rtw_join_timeout_handler() to use spin_[un]lock_irq()
instead of spin_[un]lock_bh().

_rtw_join_timeout_handler() calls rtw_do_join() which takes
pmlmepriv->scanned_queue.lock using spin_[un]lock_bh(). This
spin_unlock_bh() call re-enables softirqs which triggers an oops in
Kernel/softirq.c: __local_bh_enable_ip() when it calls
Lockdep_assert_irqs_enabled(): 

[  244.506087] WARNING: CPU: 2 PID: 0 at kernel/softirq.c:376 __local_bh_enable_ip+0xa6/0x100
...
[  244.509022] Call Trace:
[  244.509048]  <IRQ>
[  244.509100]  _rtw_join_timeout_handler+0x134/0x170 [r8723bs]
[  244.509468]  ? __pfx__rtw_join_timeout_handler+0x10/0x10 [r8723bs]
[  244.509772]  ? __pfx__rtw_join_timeout_handler+0x10/0x10 [r8723bs]
[  244.510076]  call_timer_fn+0x95/0x2a0
[  244.510200]  __run_timers.part.0+0x1da/0x2d0

This oops is causd by the switch to spin_[un]lock_irq() which disables
the IRQs for the entire duration of _rtw_join_timeout_handler().

Disabling the IRQs is not necessary since all code taking this lock
runs from either user contexts or from softirqs, switch back to
spin_[un]lock_bh() to fix this.

Fixes: 041879b12ddb ("drivers: staging: rtl8192bs: Fix deadlock in rtw_joinbss_event_prehandle()")
Cc: Duoming Zhou <duoming@zju.edu.cn>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20230221145326.7808-1-hdegoede@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/staging/rtl8723bs/core/rtw_mlme.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/rtl8723bs/core/rtw_mlme.c b/drivers/staging/rtl8723bs/core/rtw_mlme.c
index c6fd6cf741ef..ea2a6566e51b 100644
--- a/drivers/staging/rtl8723bs/core/rtw_mlme.c
+++ b/drivers/staging/rtl8723bs/core/rtw_mlme.c
@@ -1549,7 +1549,7 @@ void _rtw_join_timeout_handler(struct timer_list *t)
 	if (adapter->bDriverStopped || adapter->bSurpriseRemoved)
 		return;
 
-	spin_lock_irq(&pmlmepriv->lock);
+	spin_lock_bh(&pmlmepriv->lock);
 
 	if (rtw_to_roam(adapter) > 0) { /* join timeout caused by roaming */
 		while (1) {
@@ -1577,7 +1577,7 @@ void _rtw_join_timeout_handler(struct timer_list *t)
 
 	}
 
-	spin_unlock_irq(&pmlmepriv->lock);
+	spin_unlock_bh(&pmlmepriv->lock);
 }
 
 /*
-- 
2.35.3