[IA64] cpu-hotplug: Fixing confliction between CPU hot-add and IPI

Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Acked-by: Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

1 files changed, 6 insertions, 4 deletions

diff --git a/arch/ia64/kernel/smp.c b/arch/ia64/kernel/smp.c
index 657ac99a451c..2763e7917781 100644
--- a/arch/ia64/kernel/smp.c
+++ b/arch/ia64/kernel/smp.c
@@ -328,10 +328,14 @@ int
 smp_call_function (void (*func) (void *info), void *info, int nonatomic, int wait)
 {
         struct call_data_struct data;
-        int cpus = num_online_cpus()-1;
+        int cpus;
 
-        if (!cpus)
+        spin_lock(&call_lock);
+        cpus = num_online_cpus() - 1;
+        if (!cpus) {
+                spin_unlock(&call_lock);
                 return 0;
+        }
 
         /* Can deadlock when called with interrupts disabled */
         WARN_ON(irqs_disabled());
@@ -343,8 +347,6 @@ smp_call_function (void (*func) (void *info), void *info, int nonatomic, int wai
         if (wait)
                 atomic_set(&data.finished, 0);
 
-        spin_lock(&call_lock);
-
         call_data = &data;
         mb();   /* ensure store to call_data precedes setting of IPI_CALL_FUNC */
         send_IPI_allbutself(IPI_CALL_FUNC);