Hi Krzysztof, Thanks for the reminder! I didn't notice that s3c2410wdt_keepalive() can also be called from .ping callback. Would send a v3 patch soon. Best Regards, Chengfeng Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx> 于2023年7月5日周三 16:58写道： > > On 05/07/2023 09:23, Chengfeng Ye wrote: > > As &wdt->lock is acquired by hard irq s3c2410wdt_irq(), other > > acquisition of the same lock under process context should > > disable irq, otherwise deadlock could happen if the irq preempt > > the execution while the lock is held in process context on the > > same CPU. > > > > [Deadlock Scenario] > > s3c2410wdt_suspend() > > -> s3c2410wdt_stop() > > -> spin_lock(&wdt->lock) > > <irq iterrupt> > > -> s3c2410wdt_irq() > > -> s3c2410wdt_keepalive() > > -> spin_lock(&wdt->lock) (deadlock here) > > > > [Deadlock Scenario] > > s3c2410wdt_probe() > > -> s3c2410wdt_start() > > -> spin_lock(&wdt->lock) > > <irq iterrupt> > > -> s3c2410wdt_irq() > > -> s3c2410wdt_keepalive() > > -> spin_lock(&wdt->lock) (deadlock here) > > > > This flaw was found by an experimental static analysis tool I am > > developing for irq-related deadlock, which reported the above > > warning when analyzing the linux kernel 6.4-rc7 release. > > > > The tentative patch fix the potential deadlock by spin_lock_irqsave() > > under process context. > > > > Signed-off-by: Chengfeng Ye <dg573847474@xxxxxxxxx> > > --- > > drivers/watchdog/s3c2410_wdt.c | 10 ++++++---- > > 1 file changed, 6 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c > > index 95416a9bdd4b..2dfc0d6a3004 100644 > > --- a/drivers/watchdog/s3c2410_wdt.c > > +++ b/drivers/watchdog/s3c2410_wdt.c > > @@ -399,10 +399,11 @@ static void __s3c2410wdt_stop(struct s3c2410_wdt *wdt) > > Why you didn't update also s3c2410wdt_keepalive()? > > Best regards, > Krzysztof >
