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authorJunxiao Bi <junxiao.bi@oracle.com>2017-07-20 09:26:21 +0800
committerKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2017-07-25 11:30:59 -0400
commit4b422cb99836de3d261faec20a0329385bdec43d (patch)
treebefe906fd623d221f2ca529f7350d6d41e698b93 /drivers/block
parent76451d79bde6bed17e113f057e58e1fa5fb79e78 (diff)
downloadlinux-4b422cb99836de3d261faec20a0329385bdec43d.tar.bz2
xen-blkfront: fix mq start/stop race
When ring buf full, hw queue will be stopped. While blkif interrupt consume request and make free space in ring buf, hw queue will be started again. But since start queue is protected by spin lock while stop not, that will cause a race. interrupt: process: blkif_interrupt() blkif_queue_rq() kick_pending_request_queues_locked() blk_mq_start_stopped_hw_queues() clear_bit(BLK_MQ_S_STOPPED, &hctx->state) blk_mq_stop_hw_queue(hctx) blk_mq_run_hw_queue(hctx, async) If ring buf is made empty in this case, interrupt will never come, then the hw queue will be stopped forever, all processes waiting for the pending io in the queue will hung. Signed-off-by: Junxiao Bi <junxiao.bi@oracle.com> Reviewed-by: Ankur Arora <ankur.a.arora@oracle.com> Acked-by: Roger Pau Monné <roger.pau@citrix.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Diffstat (limited to 'drivers/block')
-rw-r--r--drivers/block/xen-blkfront.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 1799bba74390..04eeb540490f 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -906,8 +906,8 @@ out_err:
return BLK_STS_IOERR;
out_busy:
- spin_unlock_irqrestore(&rinfo->ring_lock, flags);
blk_mq_stop_hw_queue(hctx);
+ spin_unlock_irqrestore(&rinfo->ring_lock, flags);
return BLK_STS_RESOURCE;
}