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Commit cb9d7fd5 authored by Vincent Whitchurch's avatar Vincent Whitchurch Committed by Thomas Gleixner
Browse files

watchdog: Mark watchdog touch functions as notrace 



Some architectures need to use stop_machine() to patch functions for
ftrace, and the assumption is that the stopped CPUs do not make function
calls to traceable functions when they are in the stopped state.

Commit ce4f06dc ("stop_machine: Touch_nmi_watchdog() after
MULTI_STOP_PREPARE") added calls to the watchdog touch functions from
the stopped CPUs and those functions lack notrace annotations.  This
leads to crashes when enabling/disabling ftrace on ARM kernels built
with the Thumb-2 instruction set.

Fix it by adding the necessary notrace annotations.

Fixes: ce4f06dc ("stop_machine: Touch_nmi_watchdog() after MULTI_STOP_PREPARE")
Signed-off-by: default avatarVincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: oleg@redhat.com
Cc: tj@kernel.org
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20180821152507.18313-1-vincent.whitchurch@axis.com
parent 5b394b2d

kernel/watchdog.c

+2 −2
Original line number Diff line number Diff line
@@ -261,7 +261,7 @@ static void __touch_watchdog(void) 
 * entering idle state.  This should only be used for scheduler events.

 * Use touch_softlockup_watchdog() for everything else.

 */

void touch_softlockup_watchdog_sched(void)

notrace void touch_softlockup_watchdog_sched(void)

{

	/*

	 * Preemption can be enabled.  It doesn't matter which CPU's timestamp
@@ -270,7 +270,7 @@ void touch_softlockup_watchdog_sched(void) 
	raw_cpu_write(watchdog_touch_ts, 0);

}



void touch_softlockup_watchdog(void)

notrace void touch_softlockup_watchdog(void)

{

	touch_softlockup_watchdog_sched();

	wq_watchdog_touch(raw_smp_processor_id());

kernel/watchdog_hld.c

+1 −1
Original line number Diff line number Diff line
@@ -29,7 +29,7 @@ static struct cpumask dead_events_mask; 
static unsigned long hardlockup_allcpu_dumped;

static atomic_t watchdog_cpus = ATOMIC_INIT(0);



void arch_touch_nmi_watchdog(void)

notrace void arch_touch_nmi_watchdog(void)

{

	/*

	 * Using __raw here because some code paths have

kernel/workqueue.c

+1 −1
Original line number Diff line number Diff line
@@ -5574,7 +5574,7 @@ static void wq_watchdog_timer_fn(struct timer_list *unused) 
	mod_timer(&wq_watchdog_timer, jiffies + thresh);

}



void wq_watchdog_touch(int cpu)

notrace void wq_watchdog_touch(int cpu)

{

	if (cpu >= 0)

		per_cpu(wq_watchdog_touched_cpu, cpu) = jiffies;