On 28.03.2017 18:12, Denis V. Lunev wrote:
> Recently we expirience hang with iothreads enabled with the following
> call trace:
> Thread 1 (Thread 0x7fa95efebc80 (LWP 177117)):
> 0 ppoll () from /lib64/libc.so.6
> 2 qemu_poll_ns () at qemu-timer.c:313
> 3 aio_poll () at aio-posix.c:457
> 4 bdrv_flush () at block/io.c:2641
> 5 bdrv_close () at block.c:2143
> 6 bdrv_delete () at block.c:2352
> 7 bdrv_unref () at block.c:3429
> 8 blk_remove_bs () at block/block-backend.c:427
> 9 blk_delete () at block/block-backend.c:178
> 10 blk_unref () at block/block-backend.c:226
> 11 object_property_del_all () at qom/object.c:399
> 12 object_finalize () at qom/object.c:461
> 13 object_unref () at qom/object.c:898
> 14 object_property_del_child () at qom/object.c:422
> 15 qmp_marshal_device_del () at qmp-marshal.c:1145
> 16 handle_qmp_command () at /usr/src/debug/qemu-2.6.0/monitor.c:3929
>
> Technically bdrv_flush() stucks in
> while (rwco.ret == NOT_DONE) {
> aio_poll(aio_context, true);
> }
> but rwco.ret is equal to 0 thus we have missed wakeup. Code investigation
> reveals that we do not have performed aio_context_acquire() on this call
> stack.
>
> This patch adds missed lock.
>
> Signed-off-by: Denis V. Lunev <d...@openvz.org>
> CC: Kevin Wolf <kw...@redhat.com>
> CC: Max Reitz <mre...@redhat.com>
> CC: Eric Blake <ebl...@redhat.com>
> CC: Markus Armbruster <arm...@redhat.com>
> ---
> hw/core/qdev-properties-system.c | 4 ++++
> 1 file changed, 4 insertions(+)Since this file is unmaintained but this patch is mostly a matter of the block layer (and the subject starts with "block" :-)): Thanks, applied to my block tree: https://github.com/xanClic/qemu/commits/block Max
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