From 02d213009d571bcd7171e3ff9234722a11d30d1b Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Wed, 29 Nov 2017 11:25:10 +0100 Subject: block: Expect graph changes in bdrv_parent_drained_begin/end The .drained_begin/end callbacks can (directly or indirectly via aio_poll()) cause block nodes to be removed or the current BdrvChild to point to a different child node. Use QLIST_FOREACH_SAFE() to make sure we don't access invalid BlockDriverStates or accidentally continue iterating the parents of the new child node instead of the node we actually came from. Signed-off-by: Kevin Wolf Tested-by: Jeff Cody Reviewed-by: Stefan Hajnoczi Reviewed-by: Jeff Cody Reviewed-by: Alberto Garcia Reviewed-by: Fam Zheng Signed-off-by: Kevin Wolf --- block/io.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/block/io.c b/block/io.c index 4fdf93a014..6773926fc1 100644 --- a/block/io.c +++ b/block/io.c @@ -42,9 +42,9 @@ static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs, void bdrv_parent_drained_begin(BlockDriverState *bs) { - BdrvChild *c; + BdrvChild *c, *next; - QLIST_FOREACH(c, &bs->parents, next_parent) { + QLIST_FOREACH_SAFE(c, &bs->parents, next_parent, next) { if (c->role->drained_begin) { c->role->drained_begin(c); } @@ -53,9 +53,9 @@ void bdrv_parent_drained_begin(BlockDriverState *bs) void bdrv_parent_drained_end(BlockDriverState *bs) { - BdrvChild *c; + BdrvChild *c, *next; - QLIST_FOREACH(c, &bs->parents, next_parent) { + QLIST_FOREACH_SAFE(c, &bs->parents, next_parent, next) { if (c->role->drained_end) { c->role->drained_end(c); } -- cgit v1.2.1