3.16.42-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Joonyoung Shim <[email protected]> commit bc7c36eedb0c7004aa06c2afc3c5385adada8fa3 upstream. When a CPU goes offline a potentially pending timer interrupt is not cleared. When the CPU comes online again then the pending interrupt is delivered before the per cpu clockevent device is initialized. As a consequence the tick interrupt handler dereferences a NULL pointer. [ 51.251378] Unable to handle kernel NULL pointer dereference at virtual address 00000040 [ 51.289348] task: ee942d00 task.stack: ee960000 [ 51.293861] PC is at tick_periodic+0x38/0xb0 [ 51.298102] LR is at tick_handle_periodic+0x1c/0x90 Clear the pending interrupt in the cpu dying path. Fixes: 56a94f13919c ("clocksource: exynos_mct: Avoid blocking calls in the cpu hotplug notifier") Reported-by: Seung-Woo Kim <[email protected]> Signed-off-by: Joonyoung Shim <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Thomas Gleixner <[email protected]> [bwh: Backported to 3.16: add definition of the 'mevt' variable, added earlier upstream] Signed-off-by: Ben Hutchings <[email protected]> --- --- a/drivers/clocksource/exynos_mct.c +++ b/drivers/clocksource/exynos_mct.c @@ -458,10 +458,15 @@ static int exynos4_local_timer_setup(str static void exynos4_local_timer_stop(struct clock_event_device *evt) { + struct mct_clock_event_device *mevt; + + mevt = container_of(evt, struct mct_clock_event_device, evt); + evt->set_mode(CLOCK_EVT_MODE_UNUSED, evt); if (mct_int_type == MCT_INT_SPI) { if (evt->irq != -1) disable_irq_nosync(evt->irq); + exynos4_mct_write(0x1, mevt->base + MCT_L_INT_CSTAT_OFFSET); } else { disable_percpu_irq(mct_irqs[MCT_L0_IRQ]); }
