From 31b2ddfea304afc498aca8cac171020ef33eb89b Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Mon, 5 Jun 2023 10:57:10 +0200 Subject: graph-lock: Unlock the AioContext while polling If the caller keeps the AioContext lock for a block node in an iothread, polling in bdrv_graph_wrlock() deadlocks if the condition isn't fulfilled immediately. Now that all callers make sure to actually have the AioContext locked when they call bdrv_replace_child_noperm() like they should, we can change bdrv_graph_wrlock() to take a BlockDriverState whose AioContext lock the caller holds (NULL if it doesn't) and unlock it temporarily while polling. Signed-off-by: Kevin Wolf Message-ID: <20230605085711.21261-11-kwolf@redhat.com> Reviewed-by: Stefan Hajnoczi Signed-off-by: Kevin Wolf --- block.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'block.c') diff --git a/block.c b/block.c index dc691b9..0cd1a12 100644 --- a/block.c +++ b/block.c @@ -2854,7 +2854,7 @@ uint64_t bdrv_qapi_perm_to_blk_perm(BlockPermission qapi_perm) * Replaces the node that a BdrvChild points to without updating permissions. * * If @new_bs is non-NULL, the parent of @child must already be drained through - * @child. + * @child and the caller must hold the AioContext lock for @new_bs. */ static void bdrv_replace_child_noperm(BdrvChild *child, BlockDriverState *new_bs) @@ -2893,7 +2893,7 @@ static void bdrv_replace_child_noperm(BdrvChild *child, } /* TODO Pull this up into the callers to avoid polling here */ - bdrv_graph_wrlock(); + bdrv_graph_wrlock(new_bs); if (old_bs) { if (child->klass->detach) { child->klass->detach(child); -- cgit v1.1