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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: 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
View File

@ -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;