From: Duoming Zhou <duoming@zju.edu.cn> stable inclusion from stable-v5.10.114 commit ac3d0770437eedd6639271abeb5b49fd0b9941a4 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5IY1V Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ 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@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> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> Acked-by: Xie XiuQi <xiexiuqi@huawei.com> --- 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 22010384c4a3..b9646b369f8e 100644 --- a/drivers/net/hippi/rrunner.c +++ b/drivers/net/hippi/rrunner.c @@ -1353,7 +1353,9 @@ 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); -- 2.20.1