[BUG] cw1200: possible deadlock involving three functions
From: Jia-Ju Bai <hidden>
Date: 2022-02-07 16:16:51
Also in:
lkml, netdev
Hello, My static analysis tool reports a possible deadlock in the cw1200 driver in Linux 5.16: cw1200_probe_work() mutex_lock(&priv->conf_mutex); --> Line 384 (Lock A) wsm_flush_tx() wait_event_timeout(priv->bh_evt_wq, ...) --> Line 1208 (Wait X) cw1200_bh() wait_event_interruptible(priv->bh_wq, ...) --> Line 524 (Wait Y) wake_up(&priv->bh_evt_wq); --> Line 534 (Wake X) cw1200_do_join() mutex_lock(&priv->conf_mutex); --> Line 1238 (Lock A) wsm_unlock_tx() cw1200_bh_wakeup() wake_up(&priv->bh_wq); --> Line 119 (Wake Y) When cw1200_probe_work() is executed, "Wait X" is performed by holding "Lock A". If cw1200_bh() is executed at this time, because "Wait Y" is performed, "Wake X" cannot be performed to wake up "Wait X". If cw1200_do_join() is executed at this time, because "Lock A" has already been hold, "Wake Y" cannot be performed to wake up "Wait Y". 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