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[PULL 05/16] monitor: use aio_co_reschedule_self()
From: |
Kevin Wolf |
Subject: |
[PULL 05/16] monitor: use aio_co_reschedule_self() |
Date: |
Wed, 7 Feb 2024 22:55:55 +0100 |
From: Stefan Hajnoczi <stefanha@redhat.com>
The aio_co_reschedule_self() API is designed to avoid the race
condition between scheduling the coroutine in another AioContext and
yielding.
The QMP dispatch code uses the open-coded version that appears
susceptible to the race condition at first glance:
aio_co_schedule(qemu_get_aio_context(), qemu_coroutine_self());
qemu_coroutine_yield();
The code is actually safe because the iohandler and qemu_aio_context
AioContext run under the Big QEMU Lock. Nevertheless, set a good example
and use aio_co_reschedule_self() so it's obvious that there is no race.
Suggested-by: Hanna Reitz <hreitz@redhat.com>
Reviewed-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
Reviewed-by: Hanna Czenczek <hreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20240206190610.107963-6-stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
qapi/qmp-dispatch.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)
diff --git a/qapi/qmp-dispatch.c b/qapi/qmp-dispatch.c
index 176b549473..f3488afeef 100644
--- a/qapi/qmp-dispatch.c
+++ b/qapi/qmp-dispatch.c
@@ -212,8 +212,7 @@ QDict *coroutine_mixed_fn qmp_dispatch(const QmpCommandList
*cmds, QObject *requ
* executing the command handler so that it can make progress if it
* involves an AIO_WAIT_WHILE().
*/
- aio_co_schedule(qemu_get_aio_context(), qemu_coroutine_self());
- qemu_coroutine_yield();
+ aio_co_reschedule_self(qemu_get_aio_context());
}
monitor_set_cur(qemu_coroutine_self(), cur_mon);
@@ -227,9 +226,7 @@ QDict *coroutine_mixed_fn qmp_dispatch(const QmpCommandList
*cmds, QObject *requ
* Move back to iohandler_ctx so that nested event loops for
* qemu_aio_context don't start new monitor commands.
*/
- aio_co_schedule(iohandler_get_aio_context(),
- qemu_coroutine_self());
- qemu_coroutine_yield();
+ aio_co_reschedule_self(iohandler_get_aio_context());
}
} else {
/*
--
2.43.0
- [PULL 00/16] Block layer patches, Kevin Wolf, 2024/02/07
- [PULL 02/16] virtio-blk: clarify that there is at least 1 virtqueue, Kevin Wolf, 2024/02/07
- [PULL 04/16] virtio-blk: declare VirtIOBlock::rq with a type, Kevin Wolf, 2024/02/07
- [PULL 05/16] monitor: use aio_co_reschedule_self(),
Kevin Wolf <=
- [PULL 01/16] virtio-blk: enforce iothread-vq-mapping validation, Kevin Wolf, 2024/02/07
- [PULL 06/16] block-backend: Allow concurrent context changes, Kevin Wolf, 2024/02/07
- [PULL 03/16] virtio-blk: add vq_rq[] bounds check in virtio_blk_dma_restart_cb(), Kevin Wolf, 2024/02/07
- [PULL 07/16] scsi: Await request purging, Kevin Wolf, 2024/02/07
- [PULL 10/16] virtio-blk: do not use C99 mixed declarations, Kevin Wolf, 2024/02/07
- [PULL 08/16] iotests: fix leak of tmpdir in dry-run mode, Kevin Wolf, 2024/02/07
- [PULL 11/16] scsi: Don't ignore most usb-storage properties, Kevin Wolf, 2024/02/07
- [PULL 13/16] virtio-scsi: Attach event vq notifier with no_poll, Kevin Wolf, 2024/02/07
- [PULL 09/16] iotests: give tempdir an identifying name, Kevin Wolf, 2024/02/07
- [PULL 12/16] blkio: Respect memory-alignment for bounce buffer allocations, Kevin Wolf, 2024/02/07