commit c1135913c655ecfac2f3074671663f4251c8177f
author Stefan Hajnoczi <stefanha@redhat.com> Thu Sep 14 10:01:00 2023 -0400
committer Kevin Wolf <kwolf@redhat.com> Thu Dec 21 22:49:27 2023 +0100
tree 2568d85321dc64445b3038ac4a3001f20a0d6928
parent 9c67f33fcab654d6b7f9f4236c5a21ea946e0931

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>

hw/block/virtio-blk.c

diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index ee38e08..f5315df 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -105,7 +105,6 @@
     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 @@
         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 @@
     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 @@
     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 @@
         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 @@
     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 @@
 {
     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 @@
     }
 
 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 @@
         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 @@
 {
     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 @@
     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 @@
     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;
 }