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Date: Mon, 7 Feb 2022 23:31:26 +0800 From: Jia-Ju Bai <baijiaju1990@...il.com> To: chunkeey@...glemail.com, kvalo@...nel.org, davem@...emloft.net, kuba@...nel.org Cc: linux-wireless@...r.kernel.org, netdev@...r.kernel.org, linux-kernel@...r.kernel.org Subject: [BUG] intersil: p54: possible deadlock in p54_remove_interface() and p54_stop() Hello, My static analysis tool reports a possible deadlock in the p54 driver in Linux 5.16: p54_remove_interface() mutex_lock(&priv->conf_mutex); --> Line 262 (Lock A) wait_for_completion_interruptible_timeout(&priv->beacon_comp, HZ); --> Line 271 (Wait X) p54_stop() mutex_lock(&priv->conf_mutex); --> Line 208 (Lock A) p54p_stop() (call via priv->stop) p54_free_skb() p54_tx_qos_accounting_free() complete(&priv->beacon_comp); --> Line 230 (Wake X) When p54_remove_interface() is executed, "Wait X" is performed by holding "Lock A". If p54_stop() is executed at this time, "Wake X" cannot be performed to wake up "Wait X" in p54_remove_interface(), because "Lock A" has been already hold by p54_remove_interface(), causing a possible deadlock. I find that "Wait X" is performed with a timeout, to relieve the possible deadlock; but I think this timeout can cause inefficient execution. I am not quite sure whether this possible problem is real and how to fix it if it is real. Any feedback would be appreciated, thanks :) Best wishes, Jia-Ju Bai
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