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drivers: net: hippi: Fix deadlock in rr_close()
[ Upstream commit bc6de28784
]
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@zju.edu.cn>
Link: https://lore.kernel.org/r/20220417125519.82618-1-duoming@zju.edu.cn
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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1 changed files with 2 additions and 0 deletions
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@ -1355,7 +1355,9 @@ static int rr_close(struct net_device *dev)
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rrpriv->fw_running = 0;
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spin_unlock_irqrestore(&rrpriv->lock, flags);
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del_timer_sync(&rrpriv->timer);
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spin_lock_irqsave(&rrpriv->lock, flags);
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writel(0, ®s->TxPi);
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writel(0, ®s->IpRxPi);
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