From: Stefan Hajnoczi <stefanha@redhat.com>
Date: Thu, 14 Sep 2023 14:01:00 +0000 (-0400)
Subject: virtio-blk: don't lock AioContext in the completion code path
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=c1135913c655ecfac2f3074671663f4251c8177f;p=qemu.git

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>
---

diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index ee38e089bc..f5315df042 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -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;
@@ -138,7 +137,6 @@ 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)
@@ -146,19 +144,13 @@ 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)
@@ -168,11 +160,8 @@ 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);
@@ -180,9 +169,6 @@ static void virtio_blk_discard_write_zeroes_complete(void *opaque, int ret)
         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__
@@ -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);
 }
 
@@ -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;
@@ -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);
 }
@@ -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)
@@ -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;
@@ -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);
 }
 
@@ -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;
 }