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[POWERPC] Fix smp_call_function to be preempt-safe

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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>
This commit is contained in:
Hugh Dickins 2007-05-19 02:47:01 +10:00 committed by Paul Mackerras
parent d257905323
commit d3fdaed9e9
1 changed files with 18 additions and 16 deletions
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34
arch/powerpc/kernel/smp.c
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@ -201,13 +201,6 @@ int smp_call_function_map(void (*func) (void *info), void *info, int nonatomic,
/* 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;
@ -222,10 +215,17 @@ int smp_call_function_map(void (*func) (void *info), void *info, int nonatomic,
/* 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();
@ -263,6 +263,7 @@ int smp_call_function_map(void (*func) (void *info), void *info, int nonatomic,
}
}
done:
ret = 0;
out:
@ -282,16 +283,17 @@ EXPORT_SYMBOL(smp_call_function);
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 == smp_processor_id())
return -EBUSY;
cpu_set(cpu, map);
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);