diff options
author | Peter Maydell <peter.maydell@linaro.org> | 2017-04-18 16:18:15 +0100 |
---|---|---|
committer | Peter Maydell <peter.maydell@linaro.org> | 2017-04-18 16:18:15 +0100 |
commit | d1263f8f1805ffe6a9da8520a6aa96062bc794f4 (patch) | |
tree | c5fa1810e634b8bd725bd2eaafccffb4362c1552 /block | |
parent | 9c6b899f7a46893ab3b671e341a2234e9c0c060e (diff) | |
parent | 91af091f92358c2ff828fa1def1a7bea9b701cdf (diff) | |
download | qemu-d1263f8f1805ffe6a9da8520a6aa96062bc794f4.tar.gz |
Merge remote-tracking branch 'remotes/famz/tags/block-pull-request' into staging
# gpg: Signature made Tue 18 Apr 2017 15:58:32 BST
# gpg: using RSA key 0xCA35624C6A9171C6
# gpg: Good signature from "Fam Zheng <famz@redhat.com>"
# gpg: WARNING: This key is not certified with sufficiently trusted signatures!
# gpg: It is not certain that the signature belongs to the owner.
# Primary key fingerprint: 5003 7CB7 9706 0F76 F021 AD56 CA35 624C 6A91 71C6
* remotes/famz/tags/block-pull-request:
block: Drain BH in bdrv_drained_begin
block: Walk bs->children carefully in bdrv_drain_recurse
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Diffstat (limited to 'block')
-rw-r--r-- | block/io.c | 23 |
1 files changed, 20 insertions, 3 deletions
diff --git a/block/io.c b/block/io.c index 8706bfa578..a7142e00e8 100644 --- a/block/io.c +++ b/block/io.c @@ -158,7 +158,7 @@ bool bdrv_requests_pending(BlockDriverState *bs) static bool bdrv_drain_recurse(BlockDriverState *bs) { - BdrvChild *child; + BdrvChild *child, *tmp; bool waited; waited = BDRV_POLL_WHILE(bs, atomic_read(&bs->in_flight) > 0); @@ -167,8 +167,25 @@ static bool bdrv_drain_recurse(BlockDriverState *bs) bs->drv->bdrv_drain(bs); } - QLIST_FOREACH(child, &bs->children, next) { - waited |= bdrv_drain_recurse(child->bs); + QLIST_FOREACH_SAFE(child, &bs->children, next, tmp) { + BlockDriverState *bs = child->bs; + bool in_main_loop = + qemu_get_current_aio_context() == qemu_get_aio_context(); + assert(bs->refcnt > 0); + if (in_main_loop) { + /* In case the recursive bdrv_drain_recurse processes a + * block_job_defer_to_main_loop BH and modifies the graph, + * let's hold a reference to bs until we are done. + * + * IOThread doesn't have such a BH, and it is not safe to call + * bdrv_unref without BQL, so skip doing it there. + */ + bdrv_ref(bs); + } + waited |= bdrv_drain_recurse(bs); + if (in_main_loop) { + bdrv_unref(bs); + } } return waited; |