| Message ID | 20231208124352.30295-1-kwolf@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [for-8.2] block: Fix AioContext locking in qmp_block_resize() | expand |
On Fri, 8 Dec 2023 at 07:44, Kevin Wolf <kwolf@redhat.com> wrote: > > The AioContext must be unlocked before calling blk_co_unref(), because > it takes the AioContext lock internally in blk_unref_bh(), which is > scheduled in the main thread. If we don't unlock, the AioContext is > locked twice and nested event loops such as in bdrv_graph_wrlock() will > deadlock. > > Cc: qemu-stable@nongnu.org > Fixes: https://issues.redhat.com/browse/RHEL-15965 > Fixes: 0c7d204f50c382c6baac8c94bd57af4a022b3888 > Signed-off-by: Kevin Wolf <kwolf@redhat.com> > --- > blockdev.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) From IRC: 09:40 < stefanha> kwolf: "[PATCH for-8.2] block: Fix AioContext locking in qmp_block_resize()" fixes QEMU 8.1 bug and is not a regression? 09:41 < stefanha> I'm trying to understand the nature of the issue and whether to roll an -rc4 tomorrow and delay the QEMU 8.2 release by a week. 09:41 < kwolf> stefanha: Looks like it, yes 09:41 < kwolf> stefanha: Probably not worth an -rc4 on its own if there are no other fixes 09:42 < stefanha> Okay, thanks. If nothing else comes up by tomorrow I will tag v8.2.0 (final) and we can merge this immediately when the development window and -stable tree opens. > > diff --git a/blockdev.c b/blockdev.c > index 4c1177e8db..c91f49e7b6 100644 > --- a/blockdev.c > +++ b/blockdev.c > @@ -2400,8 +2400,9 @@ void coroutine_fn qmp_block_resize(const char *device, const char *node_name, > > bdrv_co_lock(bs); > bdrv_drained_end(bs); > - blk_co_unref(blk); > bdrv_co_unlock(bs); > + > + blk_co_unref(blk); > } > > void qmp_block_stream(const char *job_id, const char *device, > -- > 2.43.0 > >
Applied, thanks. Please update the changelog at https://wiki.qemu.org/ChangeLog/8.2 for any user-visible changes.
diff --git a/blockdev.c b/blockdev.c index 4c1177e8db..c91f49e7b6 100644 --- a/blockdev.c +++ b/blockdev.c @@ -2400,8 +2400,9 @@ void coroutine_fn qmp_block_resize(const char *device, const char *node_name, bdrv_co_lock(bs); bdrv_drained_end(bs); - blk_co_unref(blk); bdrv_co_unlock(bs); + + blk_co_unref(blk); } void qmp_block_stream(const char *job_id, const char *device,
The AioContext must be unlocked before calling blk_co_unref(), because it takes the AioContext lock internally in blk_unref_bh(), which is scheduled in the main thread. If we don't unlock, the AioContext is locked twice and nested event loops such as in bdrv_graph_wrlock() will deadlock. Cc: qemu-stable@nongnu.org Fixes: https://issues.redhat.com/browse/RHEL-15965 Fixes: 0c7d204f50c382c6baac8c94bd57af4a022b3888 Signed-off-by: Kevin Wolf <kwolf@redhat.com> --- blockdev.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)