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Commit 96ea91e7 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
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powerpc/watchdog: add locking around init/exit functions 



When CPUs start and stop the watchdog, they manipulate shared data
that is normally protected by the lock. Other CPUs can be running
concurrently at this time, so it's a good idea to use locking here
to be on the safe side.

Remove the barrier which is undocumented and didn't do anything.

Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 87607a30

arch/powerpc/kernel/watchdog.c

+10 −1
Original line number Diff line number Diff line
@@ -297,6 +297,8 @@ static void stop_watchdog_timer_on(unsigned int cpu) 


static int start_wd_on_cpu(unsigned int cpu)

{

	unsigned long flags;



	if (cpumask_test_cpu(cpu, &wd_cpus_enabled)) {

		WARN_ON(1);

		return 0;
@@ -311,12 +313,14 @@ static int start_wd_on_cpu(unsigned int cpu) 
	if (!cpumask_test_cpu(cpu, &watchdog_cpumask))

		return 0;



	wd_smp_lock(&flags);

	cpumask_set_cpu(cpu, &wd_cpus_enabled);

	if (cpumask_weight(&wd_cpus_enabled) == 1) {

		cpumask_set_cpu(cpu, &wd_smp_cpus_pending);

		wd_smp_last_reset_tb = get_tb();

	}

	smp_wmb();

	wd_smp_unlock(&flags);



	start_watchdog_timer_on(cpu);



	return 0;
@@ -324,12 +328,17 @@ static int start_wd_on_cpu(unsigned int cpu) 


static int stop_wd_on_cpu(unsigned int cpu)

{

	unsigned long flags;



	if (!cpumask_test_cpu(cpu, &wd_cpus_enabled))

		return 0; /* Can happen in CPU unplug case */



	stop_watchdog_timer_on(cpu);



	wd_smp_lock(&flags);

	cpumask_clear_cpu(cpu, &wd_cpus_enabled);

	wd_smp_unlock(&flags);



	wd_smp_clear_cpu_pending(cpu, get_tb());



	return 0;