smp_call_function_map() was not safe against preemption to another
cpu: its test for removing self from map was outside the spinlock.
Rearrange it a little to fix that.
smp_call_function_single() was also wrong: now get_cpu() before
excluding self, as other architectures do.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
/* Can deadlock when called with interrupts disabled */
WARN_ON(irqs_disabled());
/* Can deadlock when called with interrupts disabled */
WARN_ON(irqs_disabled());
- /* remove 'self' from the map */
- if (cpu_isset(smp_processor_id(), map))
- cpu_clear(smp_processor_id(), map);
-
- /* sanity check the map, remove any non-online processors. */
- cpus_and(map, map, cpu_online_map);
-
if (unlikely(smp_ops == NULL))
return ret;
if (unlikely(smp_ops == NULL))
return ret;
/* Must grab online cpu count with preempt disabled, otherwise
* it can change. */
num_cpus = num_online_cpus() - 1;
/* Must grab online cpu count with preempt disabled, otherwise
* it can change. */
num_cpus = num_online_cpus() - 1;
- if (!num_cpus || cpus_empty(map)) {
- ret = 0;
- goto out;
- }
+ if (!num_cpus)
+ goto done;
+
+ /* remove 'self' from the map */
+ if (cpu_isset(smp_processor_id(), map))
+ cpu_clear(smp_processor_id(), map);
+
+ /* sanity check the map, remove any non-online processors. */
+ cpus_and(map, map, cpu_online_map);
+ if (cpus_empty(map))
+ goto done;
call_data = &data;
smp_wmb();
call_data = &data;
smp_wmb();
int smp_call_function_single(int cpu, void (*func) (void *info), void *info, int nonatomic,
int wait)
{
int smp_call_function_single(int cpu, void (*func) (void *info), void *info, int nonatomic,
int wait)
{
- cpumask_t map=CPU_MASK_NONE;
+ cpumask_t map = CPU_MASK_NONE;
+ int ret = -EBUSY;
if (!cpu_online(cpu))
return -EINVAL;
if (!cpu_online(cpu))
return -EINVAL;
- if (cpu == smp_processor_id())
- return -EBUSY;
-
- return smp_call_function_map(func,info,nonatomic,wait,map);
+ if (cpu != get_cpu())
+ ret = smp_call_function_map(func,info,nonatomic,wait,map);
+ put_cpu();
+ return ret;
}
EXPORT_SYMBOL(smp_call_function_single);
}
EXPORT_SYMBOL(smp_call_function_single);