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authorKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2011-10-17 14:27:48 -0400
committerKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2011-10-17 14:28:57 -0400
commit6927d92091df2848fc0e6a693a017d4b2df549c2 (patch)
tree31fc8055bad35f8daf4325a252018dd5ff0a9150 /drivers/block/xen-blkback
parentdda1852802a6cc6fdecb9021e491b2de680c76b9 (diff)
xen/blkback: Fix two races in the handling of barrier requests.
There are two windows of opportunity to cause a race when processing a barrier request. This patch fixes this. Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Diffstat (limited to 'drivers/block/xen-blkback')
-rw-r--r--drivers/block/xen-blkback/blkback.c10
1 files changed, 5 insertions, 5 deletions
diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index a1ee2659d2b..79efec24569 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -456,15 +456,15 @@ static void xen_blk_drain_io(struct xen_blkif *blkif)
{
atomic_set(&blkif->drain, 1);
do {
+ /* The initial value is one, and one refcnt taken at the
+ * start of the xen_blkif_schedule thread. */
+ if (atomic_read(&blkif->refcnt) <= 2)
+ break;
wait_for_completion_interruptible_timeout(
&blkif->drain_complete, HZ);
if (!atomic_read(&blkif->drain))
break;
- /* The initial value is one, and one refcnt taken at the
- * start of the xen_blkif_schedule thread. */
- if (atomic_read(&blkif->refcnt) <= 2)
- break;
} while (!kthread_should_stop());
atomic_set(&blkif->drain, 0);
}
@@ -502,11 +502,11 @@ static void __end_block_io_op(struct pending_req *pending_req, int error)
make_response(pending_req->blkif, pending_req->id,
pending_req->operation, pending_req->status);
xen_blkif_put(pending_req->blkif);
- free_req(pending_req);
if (atomic_read(&pending_req->blkif->refcnt) <= 2) {
if (atomic_read(&pending_req->blkif->drain))
complete(&pending_req->blkif->drain_complete);
}
+ free_req(pending_req);
}
}