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s390/qdio: use atomic_cmpxchg

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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>
This commit is contained in:
Sebastian Ott 2017-10-26 16:36:45 +02:00 committed by Martin Schwidefsky
parent 2a2d7befd4
commit 648a6f4495
1 changed files with 1 additions and 3 deletions
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4
drivers/s390/cio/qdio_thinint.c
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@ -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);