From: Eric Blake <eblake@redhat.com>
To: Stefan Hajnoczi <stefanha@redhat.com>, qemu-devel@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>, John Snow <jsnow@redhat.com>,
qemu-block@nongnu.org
Subject: Re: [Qemu-devel] [PATCH v2 1/9] blockdev: hold AioContext for bdrv_unref() in external_snapshot_clean()
Date: Thu, 7 Dec 2017 14:32:19 -0600 [thread overview]
Message-ID: <0347dd53-3363-3fdd-8e8a-6f80f3907554@redhat.com> (raw)
In-Reply-To: <20171206144550.22295-2-stefanha@redhat.com>
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On 12/06/2017 08:45 AM, Stefan Hajnoczi wrote:
> bdrv_unref() requires the AioContext lock because bdrv_flush() uses
> BDRV_POLL_WHILE(), which assumes the AioContext is currently held. If
> BDRV_POLL_WHILE() runs without AioContext held the
> pthread_mutex_unlock() call in aio_context_release() fails.
>
> This patch moves bdrv_unref() into the AioContext locked region to solve
> the following pthread_mutex_unlock() failure:
>
> diff --git a/blockdev.c b/blockdev.c
> index 56a6b24a0b..3c8d994ced 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -1812,8 +1812,8 @@ static void external_snapshot_clean(BlkActionState *common)
> DO_UPCAST(ExternalSnapshotState, common, common);
> if (state->aio_context) {
> bdrv_drained_end(state->old_bs);
> - aio_context_release(state->aio_context);
> bdrv_unref(state->new_bs);
> + aio_context_release(state->aio_context);
Reviewed-by: Eric Blake <eblake@redhat.com>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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next prev parent reply other threads:[~2017-12-07 20:32 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-06 14:45 [Qemu-devel] [PATCH v2 0/9] blockdev: fix QMP 'transaction' with IOThreads Stefan Hajnoczi
2017-12-06 14:45 ` [Qemu-devel] [PATCH v2 1/9] blockdev: hold AioContext for bdrv_unref() in external_snapshot_clean() Stefan Hajnoczi
2017-12-07 20:32 ` Eric Blake [this message]
2017-12-06 14:45 ` [Qemu-devel] [PATCH v2 2/9] block: don't keep AioContext acquired after external_snapshot_prepare() Stefan Hajnoczi
2017-12-07 20:37 ` Eric Blake
2017-12-06 14:45 ` [Qemu-devel] [PATCH v2 3/9] block: don't keep AioContext acquired after drive_backup_prepare() Stefan Hajnoczi
2017-12-07 21:27 ` Eric Blake
2017-12-06 14:45 ` [Qemu-devel] [PATCH v2 4/9] block: don't keep AioContext acquired after blockdev_backup_prepare() Stefan Hajnoczi
2017-12-07 21:39 ` Eric Blake
2017-12-06 14:45 ` [Qemu-devel] [PATCH v2 5/9] block: don't keep AioContext acquired after internal_snapshot_prepare() Stefan Hajnoczi
2017-12-07 21:46 ` Eric Blake
2017-12-06 14:45 ` [Qemu-devel] [PATCH v2 6/9] block: drop unused BlockDirtyBitmapState->aio_context field Stefan Hajnoczi
2017-12-07 21:47 ` Eric Blake
2017-12-06 14:45 ` [Qemu-devel] [PATCH v2 7/9] iothread: add iothread_by_id() API Stefan Hajnoczi
2017-12-07 21:48 ` Eric Blake
2017-12-06 14:45 ` [Qemu-devel] [PATCH v2 8/9] blockdev: add x-blockdev-set-iothread testing command Stefan Hajnoczi
2017-12-07 21:54 ` Eric Blake
2017-12-06 14:45 ` [Qemu-devel] [PATCH v2 9/9] qemu-iotests: add 202 external snapshots IOThread test Stefan Hajnoczi
2017-12-07 21:58 ` Eric Blake
2017-12-08 10:19 ` [Qemu-devel] [Qemu-block] [PATCH v2 0/9] blockdev: fix QMP 'transaction' with IOThreads Stefan Hajnoczi
2017-12-08 13:29 ` [Qemu-devel] " Kevin Wolf
2017-12-08 15:32 ` Stefan Hajnoczi
2017-12-13 21:26 ` Paolo Bonzini
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