block: use BDRV_POLL_WHILE() in bdrv_rw_vmstate()

Calling aio_poll() directly may have been fine previously, but this is
the future, man!  The difference between an aio_poll() loop and
BDRV_POLL_WHILE() is that BDRV_POLL_WHILE() releases the AioContext
around aio_poll().

This allows the IOThread to run fd handlers or BHs to complete the
request.  Failure to release the AioContext causes deadlocks.

Using BDRV_POLL_WHILE() partially fixes a 'savevm' hang with -object
iothread.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2017-05-22 14:57:02 +01:00 committed by Kevin Wolf
parent dc88a467ec
commit ea17c9d20d

View file

@ -2023,9 +2023,7 @@ bdrv_rw_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos,
Coroutine *co = qemu_coroutine_create(bdrv_co_rw_vmstate_entry, &data);
bdrv_coroutine_enter(bs, co);
while (data.ret == -EINPROGRESS) {
aio_poll(bdrv_get_aio_context(bs), true);
}
BDRV_POLL_WHILE(bs, data.ret == -EINPROGRESS);
return data.ret;
}
}