diff options
| -rw-r--r-- | kernel/smp.c | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/kernel/smp.c b/kernel/smp.c index 7c6ded5effd9..954548906afb 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -450,7 +450,7 @@ void smp_call_function_many(const struct cpumask *mask, { struct call_function_data *data; unsigned long flags; - int cpu, next_cpu, this_cpu = smp_processor_id(); + int refs, cpu, next_cpu, this_cpu = smp_processor_id(); /* * Can deadlock when called with interrupts disabled. @@ -461,7 +461,7 @@ void smp_call_function_many(const struct cpumask *mask, WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled() && !oops_in_progress && !early_boot_irqs_disabled); - /* So, what's a CPU they want? Ignoring this one. */ + /* Try to fastpath. So, what's a CPU they want? Ignoring this one. */ cpu = cpumask_first_and(mask, cpu_online_mask); if (cpu == this_cpu) cpu = cpumask_next_and(cpu, mask, cpu_online_mask); @@ -519,6 +519,13 @@ void smp_call_function_many(const struct cpumask *mask, /* We rely on the "and" being processed before the store */ cpumask_and(data->cpumask, mask, cpu_online_mask); cpumask_clear_cpu(this_cpu, data->cpumask); + refs = cpumask_weight(data->cpumask); + + /* Some callers race with other cpus changing the passed mask */ + if (unlikely(!refs)) { + csd_unlock(&data->csd); + return; + } raw_spin_lock_irqsave(&call_function.lock, flags); /* @@ -532,7 +539,7 @@ void smp_call_function_many(const struct cpumask *mask, * to the cpumask before this write to refs, which indicates * data is on the list and is ready to be processed. */ - atomic_set(&data->refs, cpumask_weight(data->cpumask)); + atomic_set(&data->refs, refs); raw_spin_unlock_irqrestore(&call_function.lock, flags); /* |