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Message-Id: <20220510130735.116361087@linuxfoundation.org>
Date: Tue, 10 May 2022 15:07:32 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Duoming Zhou <duoming@....edu.cn>,
Paolo Abeni <pabeni@...hat.com>,
Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 47/88] drivers: net: hippi: Fix deadlock in rr_close()
From: Duoming Zhou <duoming@....edu.cn>
[ Upstream commit bc6de2878429e85c1f1afaa566f7b5abb2243eef ]
There is a deadlock in rr_close(), which is shown below:
(Thread 1) | (Thread 2)
| rr_open()
rr_close() | add_timer()
spin_lock_irqsave() //(1) | (wait a time)
... | rr_timer()
del_timer_sync() | spin_lock_irqsave() //(2)
(wait timer to stop) | ...
We hold rrpriv->lock in position (1) of thread 1 and
use del_timer_sync() to wait timer to stop, but timer handler
also need rrpriv->lock in position (2) of thread 2.
As a result, rr_close() 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/20220417125519.82618-1-duoming@zju.edu.cn
Signed-off-by: Paolo Abeni <pabeni@...hat.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
drivers/net/hippi/rrunner.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/net/hippi/rrunner.c b/drivers/net/hippi/rrunner.c
index 2a8c33abb363..a24c55a6c79a 100644
--- a/drivers/net/hippi/rrunner.c
+++ b/drivers/net/hippi/rrunner.c
@@ -1352,7 +1352,9 @@ static int rr_close(struct net_device *dev)
rrpriv->fw_running = 0;
+ spin_unlock_irqrestore(&rrpriv->lock, flags);
del_timer_sync(&rrpriv->timer);
+ spin_lock_irqsave(&rrpriv->lock, flags);
writel(0, ®s->TxPi);
writel(0, ®s->IpRxPi);
--
2.35.1
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