[S390] cio: ensure single load of irq handler pointer

Add barrier to prevent compiler from reloading pointer to irq handler.

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

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/s390/cio/airq.c b/drivers/s390/cio/airq.c
index fe6cea15bba..d3850dc30e4 100644
--- a/drivers/s390/cio/airq.c
+++ b/drivers/s390/cio/airq.c
@@ -133,6 +133,8 @@ void do_adapter_IO(u8 isc)
                 while (word) {
                         if (word & INDICATOR_MASK) {
                                 airq = airqs[isc][i];
+                                /* Make sure gcc reads from airqs only once. */
+                                barrier();
                                 if (likely(airq))
                                         airq->handler(&indicators[isc].byte[i],
                                                       airq->drv_data);