[PATCH 20.11] vhost: fix async access

[David Marchand <david.marchand@redhat.com>]

[ upstream commit 2d47fd3dfb596d266b89d82c2c4b2351c3d6fe20 ]

vq->async accesses must be protected with vq->access_lock.

Fixes: eb666d24085f ("vhost: fix async unregister deadlock")
Fixes: 0c0935c5f794 ("vhost: allow to check in-flight packets for async vhost")

Signed-off-by: David Marchand <david.marchand@redhat.com>
Acked-by: Sunil Pai G <sunil.pai.g@intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
---
 lib/librte_vhost/vhost.c | 27 +++++++++++----------------
 1 file changed, 11 insertions(+), 16 deletions(-)

diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c
index 1a7c240492..40a2554417 100644
--- a/lib/librte_vhost/vhost.c
+++ b/lib/librte_vhost/vhost.c
@@ -1693,31 +1693,26 @@ int rte_vhost_async_channel_unregister(int vid, uint16_t queue_id)
 	if (vq == NULL)
 		return ret;
 
-	ret = 0;
-
-	if (!vq->async_registered)
-		return ret;
-
 	if (!rte_spinlock_trylock(&vq->access_lock)) {
 		VHOST_LOG_CONFIG(ERR, "Failed to unregister async channel. "
 			"virt queue busy.\n");
-		return -1;
+		return ret;
 	}
 
-	if (vq->async_pkts_inflight_n) {
+	if (!vq->async_registered) {
+		ret = 0;
+	} else if (vq->async_pkts_inflight_n) {
 		VHOST_LOG_CONFIG(ERR, "Failed to unregister async channel. "
 			"async inflight packets must be completed before unregistration.\n");
-		ret = -1;
-		goto out;
-	}
-
-	vhost_free_async_mem(vq);
+	} else {
+		ret = 0;
+		vhost_free_async_mem(vq);
 
-	vq->async_ops.transfer_data = NULL;
-	vq->async_ops.check_completed_copies = NULL;
-	vq->async_registered = false;
+		vq->async_ops.transfer_data = NULL;
+		vq->async_ops.check_completed_copies = NULL;
+		vq->async_registered = false;
+	}
 
-out:
 	rte_spinlock_unlock(&vq->access_lock);
 
 	return ret;
-- 
2.36.1