[patch/s390 29/46] cio: ensure single load of irq handler pointer

[Martin Schwidefsky]

From: Heiko Carstens <heiko.carstens@xxxxxxxxxx>

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

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

 drivers/s390/cio/airq.c |    2 ++
 1 file changed, 2 insertions(+)

Index: quilt-2.6/drivers/s390/cio/airq.c
===================================================================
--- quilt-2.6.orig/drivers/s390/cio/airq.c
+++ quilt-2.6/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);

-- 
blue skies,
   Martin.

"Reality continues to ruin my life." - Calvin.

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