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powerpc/watchdog: add locking around init/exit functions

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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: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Nicholas Piggin 2017-08-09 22:41:26 +10:00 committed by Michael Ellerman
parent 87607a30be
commit 96ea91e7b6
1 changed files with 10 additions and 1 deletions
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11
arch/powerpc/kernel/watchdog.c
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@ -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;