From: Sebastian Ott <sebott@linux.vnet.ibm.com>
Date: Thu, 26 Oct 2017 14:36:45 +0000 (+0200)
Subject: s390/qdio: use atomic_cmpxchg
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=648a6f4495b183d4e0d8983ff768facb9a2185bb;p=linux.git

s390/qdio: use atomic_cmpxchg

qdio uses atomic_read to find an unused indicator and atomic_set to
flag it as used. This could lead to multiple users getting the same
indicator. Use atomic_cmpxchg instead.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Acked-by: Ursula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---

diff --git a/drivers/s390/cio/qdio_thinint.c b/drivers/s390/cio/qdio_thinint.c
index c61164f4528e1..3e587bf426b0e 100644
--- a/drivers/s390/cio/qdio_thinint.c
+++ b/drivers/s390/cio/qdio_thinint.c
@@ -56,10 +56,8 @@ static u32 *get_indicator(void)
 	int i;
 
 	for (i = 0; i < TIQDIO_NR_NONSHARED_IND; i++)
-		if (!atomic_read(&q_indicators[i].count)) {
-			atomic_set(&q_indicators[i].count, 1);
+		if (!atomic_cmpxchg(&q_indicators[i].count, 0, 1))
 			return &q_indicators[i].ind;
-		}
 
 	/* use the shared indicator */
 	atomic_inc(&q_indicators[TIQDIO_SHARED_IND].count);