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| author | Halil Pasic <pasic@linux.ibm.com> | 2019-07-23 17:11:01 +0200 |
|---|---|---|
| committer | Heiko Carstens <heiko.carstens@de.ibm.com> | 2019-07-26 13:36:18 +0200 |
| commit | 4f419eb14272e0698e8c55bb5f3f266cc2a21c81 (patch) | |
| tree | 104319c03391b176c77080df0292e26f7394a8a7 /drivers/s390/virtio | |
| parent | 1a2dcff881059dedc14fafc8a442664c8dbd60f1 (diff) | |
| download | lwn-4f419eb14272e0698e8c55bb5f3f266cc2a21c81.tar.gz lwn-4f419eb14272e0698e8c55bb5f3f266cc2a21c81.zip | |
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 39c7dcb15892 ("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: 96b14536d935 ("virtio-ccw: virtio-ccw adapter interrupt support.")
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Diffstat (limited to 'drivers/s390/virtio')
| -rw-r--r-- | drivers/s390/virtio/virtio_ccw.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c index 1a55e5942d36..957889a42d2e 100644 --- a/drivers/s390/virtio/virtio_ccw.c +++ b/drivers/s390/virtio/virtio_ccw.c @@ -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); |