From: Kevin Wolf <kwolf@redhat.com>
To: qemu-block@nongnu.org
Cc: kwolf@redhat.com, qemu-devel@nongnu.org
Subject: [PULL 11/14] virtio-blk: restart s->rq reqs in vq AioContexts
Date: Fri, 19 Jan 2024 19:13:24 +0100 [thread overview]
Message-ID: <20240119181327.236745-12-kwolf@redhat.com> (raw)
In-Reply-To: <20240119181327.236745-1-kwolf@redhat.com>
From: Stefan Hajnoczi <stefanha@redhat.com>
A virtio-blk device with the iothread-vq-mapping parameter has
per-virtqueue AioContexts. It is not thread-safe to process s->rq
requests in the BlockBackend AioContext since that may be different from
the virtqueue's AioContext to which this request belongs. The code
currently races and could crash.
Adapt virtio_blk_dma_restart_cb() to first split s->rq into per-vq lists
and then schedule a BH each vq's AioContext as necessary. This way
requests are safely processed in their vq's AioContext.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20240119135748.270944-5-stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
hw/block/virtio-blk.c | 44 ++++++++++++++++++++++++++++++++-----------
1 file changed, 33 insertions(+), 11 deletions(-)
diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index e342cb2cfb..4525988d92 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -1156,16 +1156,11 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
static void virtio_blk_dma_restart_bh(void *opaque)
{
- VirtIOBlock *s = opaque;
+ VirtIOBlockReq *req = opaque;
+ VirtIOBlock *s = req->dev; /* we're called with at least one request */
- VirtIOBlockReq *req;
MultiReqBuffer mrb = {};
- WITH_QEMU_LOCK_GUARD(&s->rq_lock) {
- req = s->rq;
- s->rq = NULL;
- }
-
while (req) {
VirtIOBlockReq *next = req->next;
if (virtio_blk_handle_request(req, &mrb)) {
@@ -1195,16 +1190,43 @@ static void virtio_blk_dma_restart_cb(void *opaque, bool running,
RunState state)
{
VirtIOBlock *s = opaque;
+ uint16_t num_queues = s->conf.num_queues;
if (!running) {
return;
}
- /* Paired with dec in virtio_blk_dma_restart_bh() */
- blk_inc_in_flight(s->conf.conf.blk);
+ /* Split the device-wide s->rq request list into per-vq request lists */
+ g_autofree VirtIOBlockReq **vq_rq = g_new0(VirtIOBlockReq *, num_queues);
+ VirtIOBlockReq *rq;
+
+ WITH_QEMU_LOCK_GUARD(&s->rq_lock) {
+ rq = s->rq;
+ s->rq = NULL;
+ }
+
+ while (rq) {
+ VirtIOBlockReq *next = rq->next;
+ uint16_t idx = virtio_get_queue_index(rq->vq);
+
+ rq->next = vq_rq[idx];
+ vq_rq[idx] = rq;
+ rq = next;
+ }
- aio_bh_schedule_oneshot(blk_get_aio_context(s->conf.conf.blk),
- virtio_blk_dma_restart_bh, s);
+ /* Schedule a BH to submit the requests in each vq's AioContext */
+ for (uint16_t i = 0; i < num_queues; i++) {
+ if (!vq_rq[i]) {
+ continue;
+ }
+
+ /* Paired with dec in virtio_blk_dma_restart_bh() */
+ blk_inc_in_flight(s->conf.conf.blk);
+
+ aio_bh_schedule_oneshot(s->vq_aio_context[i],
+ virtio_blk_dma_restart_bh,
+ vq_rq[i]);
+ }
}
static void virtio_blk_reset(VirtIODevice *vdev)
--
2.43.0
next prev parent reply other threads:[~2024-01-19 18:15 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-19 18:13 [PULL 00/14] Block layer patches Kevin Wolf
2024-01-19 18:13 ` [PULL 01/14] block/blklogwrites: Fix a bug when logging "write zeroes" operations Kevin Wolf
2024-01-19 18:13 ` [PULL 02/14] string-output-visitor: Fix (pseudo) struct handling Kevin Wolf
2024-01-19 18:13 ` [PULL 03/14] commit: Allow users to request only format driver names in backing file format Kevin Wolf
2024-01-19 18:13 ` [PULL 04/14] stream: " Kevin Wolf
2024-01-19 18:13 ` [PULL 05/14] iotests: add filter_qmp_generated_node_ids() Kevin Wolf
2024-01-19 18:13 ` [PULL 06/14] iotests: port 141 to Python for reliable QMP testing Kevin Wolf
2024-01-19 18:13 ` [PULL 07/14] monitor: only run coroutine commands in qemu_aio_context Kevin Wolf
2024-01-19 18:13 ` [PULL 08/14] virtio-blk: move dataplane code into virtio-blk.c Kevin Wolf
2024-01-19 18:13 ` [PULL 09/14] virtio-blk: rename dataplane create/destroy functions Kevin Wolf
2024-01-19 18:13 ` [PULL 10/14] virtio-blk: rename dataplane to ioeventfd Kevin Wolf
2024-01-19 18:13 ` Kevin Wolf [this message]
2024-01-19 18:13 ` [PULL 12/14] virtio-blk: tolerate failure to set BlockBackend AioContext Kevin Wolf
2024-01-19 18:13 ` [PULL 13/14] virtio-blk: always set ioeventfd during startup Kevin Wolf
2024-01-19 18:13 ` [PULL 14/14] block/blklogwrites: Protect mutable driver state with a mutex Kevin Wolf
2024-01-20 17:21 ` [PULL 00/14] Block layer patches Peter Maydell
2024-01-22 11:14 ` Kevin Wolf
2024-01-22 11:44 ` Peter Maydell
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