Patch "clocksource/exynos_mct: Clear interrupt when cpu is shut down" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

clocksource/exynos_mct: Clear interrupt when cpu is shut down

to the 4.9-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:
clocksource-exynos_mct-clear-interrupt-when-cpu-is-shut-down.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Joonyoung Shim <[email protected]>
Date: Tue, 17 Jan 2017 13:54:36 +0900
Subject: clocksource/exynos_mct: Clear interrupt when cpu is shut down

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.

---
 drivers/clocksource/exynos_mct.c |    1 +
 1 file changed, 1 insertion(+)

@@ -495,6 +495,7 @@ static int exynos4_mct_dying_cpu(unsigne
 	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]);
 	}

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/clocksource-exynos_mct-clear-interrupt-when-cpu-is-shut-down.patch