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
