diff options
| author | Duoming Zhou <duoming@zju.edu.cn> | 2022-04-17 21:54:07 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-04-20 18:47:22 +0200 |
| commit | 806c7b53414934ba2a39449b31fd1a038e500273 (patch) | |
| tree | c4c4445a6d1da2b74cbb90cf66a608d86c61d399 | |
| parent | bb5369edbab8363a8a9a0c9ba59cb85020accb68 (diff) | |
drivers: staging: rtl8192u: Fix deadlock in ieee80211_beacons_stop()
There is a deadlock in ieee80211_beacons_stop(), which is shown below:
(Thread 1) | (Thread 2)
| ieee80211_send_beacon()
ieee80211_beacons_stop() | mod_timer()
spin_lock_irqsave() //(1) | (wait a time)
... | ieee80211_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, ieee80211_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>
Link: https://lore.kernel.org/r/20220417135407.109536-1-duoming@zju.edu.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/staging/rtl8192u/ieee80211/ieee80211_softmac.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/staging/rtl8192u/ieee80211/ieee80211_softmac.c b/drivers/staging/rtl8192u/ieee80211/ieee80211_softmac.c index 4e8fbd2410a1..f0ee018b8106 100644 --- a/drivers/staging/rtl8192u/ieee80211/ieee80211_softmac.c +++ b/drivers/staging/rtl8192u/ieee80211/ieee80211_softmac.c @@ -528,9 +528,9 @@ static void ieee80211_beacons_stop(struct ieee80211_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); } void ieee80211_stop_send_beacons(struct ieee80211_device *ieee) |