[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: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 8 insertions, 8 deletions

diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 0aeb290060d9..1f4228948dc4 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -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 */