From: Duoming Zhou duoming@zju.edu.cn
[ Upstream commit 0fcddf9c7c10202946d5b19409efbdff744fba88 ]
There is a deadlock in rtw_joinbss_event_prehandle(), which is shown below:
(Thread 1) | (Thread 2) | _set_timer() rtw_joinbss_event_prehandle()| mod_timer() spin_lock_bh() //(1) | (wait a time) ... | rtw_join_timeout_handler() | _rtw_join_timeout_handler() del_timer_sync() | spin_lock_bh() //(2) (wait timer to stop) | ...
We hold pmlmepriv->lock in position (1) of thread 1 and use del_timer_sync() to wait timer to stop, but timer handler also need pmlmepriv->lock in position (2) of thread 2. As a result, rtw_joinbss_event_prehandle() will block forever.
This patch extracts del_timer_sync() from the protection of spin_lock_bh(), which could let timer handler to obtain the needed lock. What`s more, we change spin_lock_bh() to spin_lock_irq() in _rtw_join_timeout_handler() in order to prevent deadlock.
Signed-off-by: Duoming Zhou duoming@zju.edu.cn Link: https://lore.kernel.org/r/20220409072135.74248-1-duoming@zju.edu.cn Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/staging/r8188eu/core/rtw_mlme.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/staging/r8188eu/core/rtw_mlme.c b/drivers/staging/r8188eu/core/rtw_mlme.c index 6f0bff186477..76cf6a69bf0f 100644 --- a/drivers/staging/r8188eu/core/rtw_mlme.c +++ b/drivers/staging/r8188eu/core/rtw_mlme.c @@ -1071,8 +1071,10 @@ void rtw_joinbss_event_prehandle(struct adapter *adapter, u8 *pbuf) rtw_indicate_connect(adapter); }
+ spin_unlock_bh(&pmlmepriv->lock); /* s5. Cancel assoc_timer */ del_timer_sync(&pmlmepriv->assoc_timer); + spin_lock_bh(&pmlmepriv->lock); } else { spin_unlock_bh(&pmlmepriv->scanned_queue.lock); goto ignore_joinbss_callback; @@ -1310,7 +1312,7 @@ void _rtw_join_timeout_handler (struct adapter *adapter) if (adapter->bDriverStopped || adapter->bSurpriseRemoved) return;
- spin_lock_bh(&pmlmepriv->lock); + spin_lock_irq(&pmlmepriv->lock);
if (rtw_to_roaming(adapter) > 0) { /* join timeout caused by roaming */ while (1) { @@ -1329,7 +1331,7 @@ void _rtw_join_timeout_handler (struct adapter *adapter) rtw_indicate_disconnect(adapter); free_scanqueue(pmlmepriv);/* */ } - spin_unlock_bh(&pmlmepriv->lock); + spin_unlock_irq(&pmlmepriv->lock);
}