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Subject[PATCH 2/2] powerpc/watchdog: ensure watchdog data accesses are protected
Date
The wd_smp_cpus_pending CPU mask should be accessed under the protection of
the __wd_smp_lock.

This prevents false alarm to be raised when the system is under an heavy
stress. This has been seen while doing LPM on large system with a big
workload.

Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
---
arch/powerpc/kernel/watchdog.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/kernel/watchdog.c b/arch/powerpc/kernel/watchdog.c
index bc7411327066..8d7a1a86187e 100644
--- a/arch/powerpc/kernel/watchdog.c
+++ b/arch/powerpc/kernel/watchdog.c
@@ -203,12 +203,13 @@ static void watchdog_smp_panic(int cpu, u64 tb)

static void wd_smp_clear_cpu_pending(int cpu, u64 tb)
{
+ unsigned long flags;
+
+ wd_smp_lock(&flags);
if (!cpumask_test_cpu(cpu, &wd_smp_cpus_pending)) {
if (unlikely(cpumask_test_cpu(cpu, &wd_smp_cpus_stuck))) {
struct pt_regs *regs = get_irq_regs();
- unsigned long flags;

- wd_smp_lock(&flags);
cpumask_clear_cpu(cpu, &wd_smp_cpus_stuck);
wd_smp_unlock(&flags);

@@ -219,22 +220,23 @@ static void wd_smp_clear_cpu_pending(int cpu, u64 tb)
show_regs(regs);
else
dump_stack();
+ return;
}
+
+ wd_smp_unlock(&flags);
return;
}
+
cpumask_clear_cpu(cpu, &wd_smp_cpus_pending);
if (cpumask_empty(&wd_smp_cpus_pending)) {
- unsigned long flags;
-
- wd_smp_lock(&flags);
if (cpumask_empty(&wd_smp_cpus_pending)) {
wd_smp_last_reset_tb = tb;
cpumask_andnot(&wd_smp_cpus_pending,
&wd_cpus_enabled,
&wd_smp_cpus_stuck);
}
- wd_smp_unlock(&flags);
}
+ wd_smp_unlock(&flags);
}

static void watchdog_timer_interrupt(int cpu)
--
2.33.1
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