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Commit 85cb185d authored by Heiko Carstens's avatar Heiko Carstens Committed by Martin Schwidefsky
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[S390] smp: __smp_call_function_map vs cpu_online_map fix. 



Both smp_call_function() and __smp_call_function_map() access
cpu_online_map. Both functions run with preemption disabled which
protects for cpus going offline. However new cpus can be added and
therefore the cpu_online_map can change unexpectedly.
So use the call_lock to protect against changes to the cpu_online_map
in start_secondary() and all smp_call_* functions.

Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent f455adcf

arch/s390/kernel/smp.c

+8 −8
Original line number Diff line number Diff line
@@ -139,7 +139,6 @@ static void __smp_call_function_map(void (*func) (void *info), void *info, 
	if (wait)

		data.finished = CPU_MASK_NONE;



	spin_lock(&call_lock);

	call_data = &data;



	for_each_cpu_mask(cpu, map)
@@ -151,7 +150,6 @@ static void __smp_call_function_map(void (*func) (void *info), void *info, 
	if (wait)

		while (!cpus_equal(map, data.finished))

			cpu_relax();

	spin_unlock(&call_lock);

out:

	if (local) {

		local_irq_disable();
@@ -177,11 +175,11 @@ int smp_call_function(void (*func) (void *info), void *info, int nonatomic, 
{

	cpumask_t map;



	preempt_disable();

	spin_lock(&call_lock);

	map = cpu_online_map;

	cpu_clear(smp_processor_id(), map);

	__smp_call_function_map(func, info, nonatomic, wait, map);

	preempt_enable();

	spin_unlock(&call_lock);

	return 0;

}

EXPORT_SYMBOL(smp_call_function);
@@ -202,10 +200,10 @@ EXPORT_SYMBOL(smp_call_function); 
int smp_call_function_single(int cpu, void (*func) (void *info), void *info,

			     int nonatomic, int wait)

{

	preempt_disable();

	spin_lock(&call_lock);

	__smp_call_function_map(func, info, nonatomic, wait,

				cpumask_of_cpu(cpu));

	preempt_enable();

	spin_unlock(&call_lock);

	return 0;

}

EXPORT_SYMBOL(smp_call_function_single);
@@ -228,10 +226,10 @@ EXPORT_SYMBOL(smp_call_function_single); 
int smp_call_function_mask(cpumask_t mask, void (*func)(void *), void *info,

			   int wait)

{

	preempt_disable();

	spin_lock(&call_lock);

	cpu_clear(smp_processor_id(), mask);

	__smp_call_function_map(func, info, 0, wait, mask);

	preempt_enable();

	spin_unlock(&call_lock);

	return 0;

}

EXPORT_SYMBOL(smp_call_function_mask);
@@ -592,7 +590,9 @@ int __cpuinit start_secondary(void *cpuvoid) 
	pfault_init();



	/* Mark this cpu as online */

	spin_lock(&call_lock);

	cpu_set(smp_processor_id(), cpu_online_map);

	spin_unlock(&call_lock);

	/* Switch on interrupts */

	local_irq_enable();

	/* Print info about this processor */