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virtio/s390: fix race on airq_areas[] 

The access to airq_areas was racy ever since the adapter interrupts got
introduced to virtio-ccw, but since commit 39c7dcb158 ("virtio/s390:
make airq summary indicators DMA") this became an issue in practice as
well. Namely before that commit the airq_info that got overwritten was
still functional. After that commit however the two infos share a
summary_indicator, which aggravates the situation. Which means
auto-online mechanism occasionally hangs the boot with virtio_blk.

Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
Reported-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 96b14536d9 ("virtio-ccw: virtio-ccw adapter interrupt support.")
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
This commit is contained in:
Halil Pasic 2019-07-23 17:11:01 +02:00 committed by Heiko Carstens
parent 1a2dcff881
commit 4f419eb142
1 changed files with 4 additions and 0 deletions
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4
drivers/s390/virtio/virtio_ccw.c
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@ -145,6 +145,8 @@ struct airq_info {
struct airq_iv *aiv;
};
static struct airq_info *airq_areas[MAX_AIRQ_AREAS];
static DEFINE_MUTEX(airq_areas_lock);
static u8 *summary_indicators;
static inline u8 *get_summary_indicator(struct airq_info *info)
@ -265,9 +267,11 @@ static unsigned long get_airq_indicator(struct virtqueue *vqs[], int nvqs,
unsigned long bit, flags;
for (i = 0; i < MAX_AIRQ_AREAS && !indicator_addr; i++) {
mutex_lock(&airq_areas_lock);
if (!airq_areas[i])
airq_areas[i] = new_airq_info(i);
info = airq_areas[i];
mutex_unlock(&airq_areas_lock);
if (!info)
return 0;
write_lock_irqsave(&info->lock, flags);