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virtio-blk: don't lock AioContext in the completion code path 
Nothing in the completion code path relies on the AioContext lock
anymore. Virtqueues are only accessed from one thread at any moment and
the s->rq global state is protected by its own lock now.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230914140101.1065008-4-stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Stefan Hajnoczi authored and Kevin Wolf committed Dec 21, 2023
1 parent 9c67f33 commit c113591
Showing 1 changed file with 4 additions and 30 deletions.
34 changes: 4 additions & 30 deletions hw/block/virtio-blk.c
View file
Expand Up @@ -105,7 +105,6 @@ static void virtio_blk_rw_complete(void *opaque, int ret)
VirtIOBlock *s = next->dev;
VirtIODevice *vdev = VIRTIO_DEVICE(s);

aio_context_acquire(blk_get_aio_context(s->conf.conf.blk));
while (next) {
VirtIOBlockReq *req = next;
next = req->mr_next;
Expand Down Expand Up @@ -138,27 +137,20 @@ static void virtio_blk_rw_complete(void *opaque, int ret)
block_acct_done(blk_get_stats(s->blk), &req->acct);
virtio_blk_free_request(req);
}
aio_context_release(blk_get_aio_context(s->conf.conf.blk));
}

static void virtio_blk_flush_complete(void *opaque, int ret)
{
VirtIOBlockReq *req = opaque;
VirtIOBlock *s = req->dev;

aio_context_acquire(blk_get_aio_context(s->conf.conf.blk));
if (ret) {
if (virtio_blk_handle_rw_error(req, -ret, 0, true)) {
goto out;
}
if (ret && virtio_blk_handle_rw_error(req, -ret, 0, true)) {
return;
}

virtio_blk_req_complete(req, VIRTIO_BLK_S_OK);
block_acct_done(blk_get_stats(s->blk), &req->acct);
virtio_blk_free_request(req);

out:
aio_context_release(blk_get_aio_context(s->conf.conf.blk));
}

static void virtio_blk_discard_write_zeroes_complete(void *opaque, int ret)
Expand All @@ -168,21 +160,15 @@ static void virtio_blk_discard_write_zeroes_complete(void *opaque, int ret)
bool is_write_zeroes = (virtio_ldl_p(VIRTIO_DEVICE(s), &req->out.type) &
~VIRTIO_BLK_T_BARRIER) == VIRTIO_BLK_T_WRITE_ZEROES;

aio_context_acquire(blk_get_aio_context(s->conf.conf.blk));
if (ret) {
if (virtio_blk_handle_rw_error(req, -ret, false, is_write_zeroes)) {
goto out;
}
if (ret && virtio_blk_handle_rw_error(req, -ret, false, is_write_zeroes)) {
return;
}

virtio_blk_req_complete(req, VIRTIO_BLK_S_OK);
if (is_write_zeroes) {
block_acct_done(blk_get_stats(s->blk), &req->acct);
}
virtio_blk_free_request(req);

out:
aio_context_release(blk_get_aio_context(s->conf.conf.blk));
}

#ifdef __linux__
Expand Down Expand Up @@ -229,10 +215,8 @@ static void virtio_blk_ioctl_complete(void *opaque, int status)
virtio_stl_p(vdev, &scsi->data_len, hdr->dxfer_len);

out:
aio_context_acquire(blk_get_aio_context(s->conf.conf.blk));
virtio_blk_req_complete(req, status);
virtio_blk_free_request(req);
aio_context_release(blk_get_aio_context(s->conf.conf.blk));
g_free(ioctl_req);
}

Expand Down Expand Up @@ -672,7 +656,6 @@ static void virtio_blk_zone_report_complete(void *opaque, int ret)
{
ZoneCmdData *data = opaque;
VirtIOBlockReq *req = data->req;
VirtIOBlock *s = req->dev;
VirtIODevice *vdev = VIRTIO_DEVICE(req->dev);
struct iovec *in_iov = data->in_iov;
unsigned in_num = data->in_num;
Expand Down Expand Up @@ -763,10 +746,8 @@ static void virtio_blk_zone_report_complete(void *opaque, int ret)
}

out:
aio_context_acquire(blk_get_aio_context(s->conf.conf.blk));
virtio_blk_req_complete(req, err_status);
virtio_blk_free_request(req);
aio_context_release(blk_get_aio_context(s->conf.conf.blk));
g_free(data->zone_report_data.zones);
g_free(data);
}
Expand Down Expand Up @@ -829,10 +810,8 @@ static void virtio_blk_zone_mgmt_complete(void *opaque, int ret)
err_status = VIRTIO_BLK_S_ZONE_INVALID_CMD;
}

aio_context_acquire(blk_get_aio_context(s->conf.conf.blk));
virtio_blk_req_complete(req, err_status);
virtio_blk_free_request(req);
aio_context_release(blk_get_aio_context(s->conf.conf.blk));
}

static int virtio_blk_handle_zone_mgmt(VirtIOBlockReq *req, BlockZoneOp op)
Expand Down Expand Up @@ -882,7 +861,6 @@ static void virtio_blk_zone_append_complete(void *opaque, int ret)
{
ZoneCmdData *data = opaque;
VirtIOBlockReq *req = data->req;
VirtIOBlock *s = req->dev;
VirtIODevice *vdev = VIRTIO_DEVICE(req->dev);
int64_t append_sector, n;
uint8_t err_status = VIRTIO_BLK_S_OK;
Expand All @@ -905,10 +883,8 @@ static void virtio_blk_zone_append_complete(void *opaque, int ret)
trace_virtio_blk_zone_append_complete(vdev, req, append_sector, ret);

out:
aio_context_acquire(blk_get_aio_context(s->conf.conf.blk));
virtio_blk_req_complete(req, err_status);
virtio_blk_free_request(req);
aio_context_release(blk_get_aio_context(s->conf.conf.blk));
g_free(data);
}

Expand Down Expand Up @@ -944,10 +920,8 @@ static int virtio_blk_handle_zone_append(VirtIOBlockReq *req,
return 0;

out:
aio_context_acquire(blk_get_aio_context(s->conf.conf.blk));
virtio_blk_req_complete(req, err_status);
virtio_blk_free_request(req);
aio_context_release(blk_get_aio_context(s->conf.conf.blk));
return err_status;
}

Expand Down

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