[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>

diff --git a/arch/ia64/kernel/smp.c b/arch/ia64/kernel/smp.c
index 657ac99a451cf8d550e10d5fa52af12f130b3588..2763e791778183f805a6540221431eb03f0fdfef 100644 (file)
--- 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);