[dpdk-dev] [PATCH v2 3/4] vhost: avoid deadlock on async register

[Jiayu Hu]

Users can register async copy device in vring_state_changed(),
when vhost queue is enabled. However, a deadlock occurs inside
rte_vhost_async_channel_register(), if VHOST_USER_F_PROTOCOL_FEATURES
is not supported, as vhost_user_msg_handler() takes vq->access_lock
before calling vhost_user_set_vring_kick().

This patch avoids async register deadlock by removing calling
vring_state_changed() in vhost_user_set_vring_kick(). It's safe
as vhost_user_msg_handler() will call vring_state_changed() anyway.

Signed-off-by: Jiayu Hu <jiayu...@intel.com>
---
 lib/librte_vhost/vhost_user.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
index 44c0452..8f0eba6 100644
--- a/lib/librte_vhost/vhost_user.c
+++ b/lib/librte_vhost/vhost_user.c
@@ -1918,9 +1918,6 @@ vhost_user_set_vring_kick(struct virtio_net **pdev, 
struct VhostUserMsg *msg,
         */
        if (!(dev->features & (1ULL << VHOST_USER_F_PROTOCOL_FEATURES))) {
                vq->enabled = true;
-               if (dev->notify_ops->vring_state_changed)
-                       dev->notify_ops->vring_state_changed(
-                               dev->vid, file.index, 1);
        }
 
        if (vq->ready) {
-- 
2.7.4