[PATCH v2] vhost: fix deadlock when handling user messages

[Wenwu Ma]

In vhost_user_msg_handler(), if vhost message handling
failed, we should check whether the queue is locked and
release the lock before returning. Or, it will cause a
deadlock later.

Fixes: 7f31d4ea05ca ("vhost: fix lock on device readiness notification")
Cc: sta...@dpdk.org

Signed-off-by: Wenwu Ma <wenwux...@intel.com>
---
 lib/vhost/vhost_user.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/lib/vhost/vhost_user.c b/lib/vhost/vhost_user.c
index 1d390677fa..4baf969ee0 100644
--- a/lib/vhost/vhost_user.c
+++ b/lib/vhost/vhost_user.c
@@ -2976,7 +2976,6 @@ vhost_user_msg_handler(int vid, int fd)
                return -1;
        }
 
-       ret = 0;
        request = ctx.msg.request.master;
        if (request > VHOST_USER_NONE && request < VHOST_USER_MAX &&
                        vhost_message_str[request]) {
@@ -3113,9 +3112,11 @@ vhost_user_msg_handler(int vid, int fd)
                send_vhost_reply(dev, fd, &ctx);
        } else if (ret == RTE_VHOST_MSG_RESULT_ERR) {
                VHOST_LOG_CONFIG(ERR, "(%s) vhost message handling failed.\n", 
dev->ifname);
-               return -1;
+               ret = -1;
+               goto unlock;
        }
 
+       ret = 0;
        for (i = 0; i < dev->nr_vring; i++) {
                struct vhost_virtqueue *vq = dev->virtqueue[i];
                bool cur_ready = vq_is_ready(dev, vq);
@@ -3126,10 +3127,11 @@ vhost_user_msg_handler(int vid, int fd)
                }
        }
 
+unlock:
        if (unlock_required)
                vhost_user_unlock_all_queue_pairs(dev);
 
-       if (!virtio_is_ready(dev))
+       if (ret != 0 || !virtio_is_ready(dev))
                goto out;
 
        /*
@@ -3156,7 +3158,7 @@ vhost_user_msg_handler(int vid, int fd)
        }
 
 out:
-       return 0;
+       return ret;
 }
 
 static int process_slave_message_reply(struct virtio_net *dev,
-- 
2.25.1