Update Linux to v5.10.109
Sourced from [1]
[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.10.109.tar.xz
Change-Id: I19bca9fc6762d4e63bcf3e4cba88bbe560d9c76c
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/arch/powerpc/kernel/watchdog.c b/arch/powerpc/kernel/watchdog.c
index af3c15a..75b2a6c 100644
--- a/arch/powerpc/kernel/watchdog.c
+++ b/arch/powerpc/kernel/watchdog.c
@@ -132,6 +132,10 @@
{
cpumask_or(&wd_smp_cpus_stuck, &wd_smp_cpus_stuck, cpumask);
cpumask_andnot(&wd_smp_cpus_pending, &wd_smp_cpus_pending, cpumask);
+ /*
+ * See wd_smp_clear_cpu_pending()
+ */
+ smp_mb();
if (cpumask_empty(&wd_smp_cpus_pending)) {
wd_smp_last_reset_tb = tb;
cpumask_andnot(&wd_smp_cpus_pending,
@@ -217,13 +221,44 @@
cpumask_clear_cpu(cpu, &wd_smp_cpus_stuck);
wd_smp_unlock(&flags);
+ } else {
+ /*
+ * The last CPU to clear pending should have reset the
+ * watchdog so we generally should not find it empty
+ * here if our CPU was clear. However it could happen
+ * due to a rare race with another CPU taking the
+ * last CPU out of the mask concurrently.
+ *
+ * We can't add a warning for it. But just in case
+ * there is a problem with the watchdog that is causing
+ * the mask to not be reset, try to kick it along here.
+ */
+ if (unlikely(cpumask_empty(&wd_smp_cpus_pending)))
+ goto none_pending;
}
return;
}
+
cpumask_clear_cpu(cpu, &wd_smp_cpus_pending);
+
+ /*
+ * Order the store to clear pending with the load(s) to check all
+ * words in the pending mask to check they are all empty. This orders
+ * with the same barrier on another CPU. This prevents two CPUs
+ * clearing the last 2 pending bits, but neither seeing the other's
+ * store when checking if the mask is empty, and missing an empty
+ * mask, which ends with a false positive.
+ */
+ smp_mb();
if (cpumask_empty(&wd_smp_cpus_pending)) {
unsigned long flags;
+none_pending:
+ /*
+ * Double check under lock because more than one CPU could see
+ * a clear mask with the lockless check after clearing their
+ * pending bits.
+ */
wd_smp_lock(&flags);
if (cpumask_empty(&wd_smp_cpus_pending)) {
wd_smp_last_reset_tb = tb;
@@ -314,8 +349,12 @@
{
unsigned long ticks = tb_ticks_per_usec * wd_timer_period_ms * 1000;
int cpu = smp_processor_id();
- u64 tb = get_tb();
+ u64 tb;
+ if (!cpumask_test_cpu(cpu, &watchdog_cpumask))
+ return;
+
+ tb = get_tb();
if (tb - per_cpu(wd_timer_tb, cpu) >= ticks) {
per_cpu(wd_timer_tb, cpu) = tb;
wd_smp_clear_cpu_pending(cpu, tb);