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
