From eb39a7c0355393c5a8d930f342ad7a6231b552c4 Mon Sep 17 00:00:00 2001 From: David Kozub Date: Thu, 19 Oct 2017 22:57:02 +0200 Subject: clockevents/drivers/cs5535: Improve resilience to spurious interrupts The interrupt handler mfgpt_tick() is not robust versus spurious interrupts which happen before the clock event device is registered and fully initialized. The reason is that the safe guard against spurious interrupts solely checks for the clockevents shutdown state, but lacks a check for detached state. If the interrupt hits while the device is in detached state it passes the safe guard and dereferences the event handler call back which is NULL. Add the missing state check. Fixes: 8f9327cbb6e8 ("clockevents/drivers/cs5535: Migrate to new 'set-state' interface") Suggested-by: Thomas Gleixner Signed-off-by: David Kozub Signed-off-by: Thomas Gleixner Cc: Daniel Lezcano Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20171020093103.3317F6004D@linux.fjfi.cvut.cz --- drivers/clocksource/cs5535-clockevt.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/clocksource/cs5535-clockevt.c b/drivers/clocksource/cs5535-clockevt.c index a1df588343f2..1de8cac99a0e 100644 --- a/drivers/clocksource/cs5535-clockevt.c +++ b/drivers/clocksource/cs5535-clockevt.c @@ -117,7 +117,8 @@ static irqreturn_t mfgpt_tick(int irq, void *dev_id) /* Turn off the clock (and clear the event) */ disable_timer(cs5535_event_clock); - if (clockevent_state_shutdown(&cs5535_clockevent)) + if (clockevent_state_detached(&cs5535_clockevent) || + clockevent_state_shutdown(&cs5535_clockevent)) return IRQ_HANDLED; /* Clear the counter */ -- cgit v1.2.3-70-g09d2