On 12/06/2017 08:45 AM, Stefan Hajnoczi wrote: > It is not necessary to hold AioContext across transactions anymore since > bdrv_drained_begin/end() is used to keep the nodes quiesced. In fact, > using the AioContext lock for this purpose was always buggy. > > This patch reduces the scope of AioContext locked regions. This is not > just a cleanup but also fixes hangs that occur in BDRV_POLL_WHILE() > because it is unware of recursive locking and does not release the
s/unware/unaware/
> AioContext the necessary number of times to allow progress to be made.
>
> Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
> ---
> blockdev.c | 71
> ++++++++++++++++++++++++++++++++++++++++++--------------------
> 1 file changed, 48 insertions(+), 23 deletions(-)
>
> @@ -1662,31 +1662,32 @@ static void external_snapshot_prepare(BlkActionState
> *common,
> return;
> }
>
> - /* Acquire AioContext now so any threads operating on old_bs stop */
> - state->aio_context = bdrv_get_aio_context(state->old_bs);
> - aio_context_acquire(state->aio_context);
> + aio_context = bdrv_get_aio_context(state->old_bs);
> + aio_context_acquire(aio_context);
> +
> + /* Paired with .clean() */
> bdrv_drained_begin(state->old_bs);
>
> if (!bdrv_is_inserted(state->old_bs)) {
> error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, device);
> - return;
> + goto out;
> }
Using gcc/clang's __attribute__((cleanup)) would make this so much nicer ;)
Reviewed-by: Eric Blake <ebl...@redhat.com>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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