This is a note to let you know that I've just added the patch titled usb: chipidea: fix deadlock in ci_otg_del_timer to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: usb-chipidea-fix-deadlock-in-ci_otg_del_timer.patch and it can be found in the queue-4.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 7a58b8d6021426b796eebfae80983374d9a80a75 Mon Sep 17 00:00:00 2001 From: Duoming Zhou <duoming@xxxxxxxxxx> Date: Sun, 18 Sep 2022 11:33:12 +0800 Subject: usb: chipidea: fix deadlock in ci_otg_del_timer From: Duoming Zhou <duoming@xxxxxxxxxx> commit 7a58b8d6021426b796eebfae80983374d9a80a75 upstream. There is a deadlock in ci_otg_del_timer(), the process is shown below: (thread 1) | (thread 2) ci_otg_del_timer() | ci_otg_hrtimer_func() ... | spin_lock_irqsave() //(1) | ... ... | hrtimer_cancel() | spin_lock_irqsave() //(2) (block forever) We hold ci->lock in position (1) and use hrtimer_cancel() to wait ci_otg_hrtimer_func() to stop, but ci_otg_hrtimer_func() also need ci->lock in position (2). As a result, the hrtimer_cancel() in ci_otg_del_timer() will be blocked forever. This patch extracts hrtimer_cancel() from the protection of spin_lock_irqsave() in order that the ci_otg_hrtimer_func() could obtain the ci->lock. What`s more, there will be no race happen. Because the "next_timer" is always under the protection of spin_lock_irqsave() and we only check whether "next_timer" equals to NUM_OTG_FSM_TIMERS in the following code. Fixes: 3a316ec4c91c ("usb: chipidea: use hrtimer for otg fsm timers") Cc: stable <stable@xxxxxxxxxx> Signed-off-by: Duoming Zhou <duoming@xxxxxxxxxx> Link: https://lore.kernel.org/r/20220918033312.94348-1-duoming@xxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/usb/chipidea/otg_fsm.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/usb/chipidea/otg_fsm.c +++ b/drivers/usb/chipidea/otg_fsm.c @@ -260,8 +260,10 @@ static void ci_otg_del_timer(struct ci_h ci->enabled_otg_timer_bits &= ~(1 << t); if (ci->next_otg_timer == t) { if (ci->enabled_otg_timer_bits == 0) { + spin_unlock_irqrestore(&ci->lock, flags); /* No enabled timers after delete it */ hrtimer_cancel(&ci->otg_fsm_hrtimer); + spin_lock_irqsave(&ci->lock, flags); ci->next_otg_timer = NUM_OTG_FSM_TIMERS; } else { /* Find the next timer */ Patches currently in stable-queue which might be from duoming@xxxxxxxxxx are queue-4.14/usb-chipidea-fix-deadlock-in-ci_otg_del_timer.patch queue-4.14/tty-n_gsm-fix-sleep-in-atomic-context-bug-in-gsm_con.patch