drivers: staging: rtl8723bs: Fix locking in _rtw_join_timeout_handler()

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>

diff --git a/drivers/staging/rtl8723bs/core/rtw_mlme.c b/drivers/staging/rtl8723bs/core/rtw_mlme.c
index c6fd6cf..ea2a656 100644 (file)
--- 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);
 }
 
 /*