| Message ID | 30b73126e09c47d9f86d705c26efb63da0bab157.1649310812.git.duoming@zju.edu.cn |
|---|---|
| State | New |
| Headers | show |
| Series | Fix deadlocks caused by del_timer_sync() | expand |
diff --git a/drivers/staging/rtl8192e/rtllib_softmac.c b/drivers/staging/rtl8192e/rtllib_softmac.c index 4b6c2295a3c..3ea542e9008 100644 --- a/drivers/staging/rtl8192e/rtllib_softmac.c +++ b/drivers/staging/rtl8192e/rtllib_softmac.c @@ -651,10 +651,10 @@ static void rtllib_beacons_stop(struct rtllib_device *ieee) spin_lock_irqsave(&ieee->beacon_lock, flags); ieee->beacon_txing = 0; - del_timer_sync(&ieee->beacon_timer); spin_unlock_irqrestore(&ieee->beacon_lock, flags); + del_timer_sync(&ieee->beacon_timer); }
There is a deadlock in rtllib_beacons_stop(), which is shown below: (Thread 1) | (Thread 2) | rtllib_send_beacon() rtllib_beacons_stop() | mod_timer() spin_lock_irqsave() //(1) | (wait a time) ... | rtllib_send_beacon_cb() del_timer_sync() | spin_lock_irqsave() //(2) (wait timer to stop) | ... We hold ieee->beacon_lock in position (1) of thread 1 and use del_timer_sync() to wait timer to stop, but timer handler also need ieee->beacon_lock in position (2) of thread 2. As a result, rtllib_beacons_stop() will block forever. This patch extracts del_timer_sync() from the protection of spin_lock_irqsave(), which could let timer handler to obtain the needed lock. Signed-off-by: Duoming Zhou <duoming@zju.edu.cn> --- drivers/staging/rtl8192e/rtllib_softmac.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)