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Message-Id: <20220607174846.477972-12-sashal@kernel.org>
Date: Tue, 7 Jun 2022 13:47:38 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc: Duoming Zhou <duoming@....edu.cn>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Sasha Levin <sashal@...nel.org>, baihaowen@...zu.com,
dan.carpenter@...cle.com, wjsota@...il.com, len.baker@....com,
dave@...olabs.net, edumazet@...gle.com, yangyingliang@...wei.com,
linux-staging@...ts.linux.dev
Subject: [PATCH AUTOSEL 5.18 12/68] drivers: staging: rtl8192e: Fix deadlock in rtllib_beacons_stop()
From: Duoming Zhou <duoming@....edu.cn>
[ Upstream commit 9b6bdbd9337de3917945847bde262a34a87a6303 ]
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@....edu.cn>
Link: https://lore.kernel.org/r/20220417141641.124388-1-duoming@zju.edu.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
drivers/staging/rtl8192e/rtllib_softmac.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/staging/rtl8192e/rtllib_softmac.c b/drivers/staging/rtl8192e/rtllib_softmac.c
index 4b6c2295a3cf..b5a38f0a8d79 100644
--- a/drivers/staging/rtl8192e/rtllib_softmac.c
+++ b/drivers/staging/rtl8192e/rtllib_softmac.c
@@ -651,9 +651,9 @@ 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);
}
--
2.35.1
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