[PATCH] vhost: use try_lock in rte_vhost_vring_call

[Changpeng Liu <changpeng.liu@intel.com>]

Note that this function is in data path, so the thread context
may not same as socket messages processing context, by using
try_lock here, users can have another try in case of VQ's access
lock is held by `vhost-events` thread.

Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>
---
 lib/vhost/vhost.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/vhost/vhost.c b/lib/vhost/vhost.c
index 60cb05a0ff..072d2acb7b 100644
--- a/lib/vhost/vhost.c
+++ b/lib/vhost/vhost.c
@@ -1329,7 +1329,11 @@ rte_vhost_vring_call(int vid, uint16_t vring_idx)
 	if (!vq)
 		return -1;
 
-	rte_spinlock_lock(&vq->access_lock);
+	if (!rte_spinlock_trylock(&vq->access_lock)) {
+		VHOST_LOG_CONFIG(dev->ifname, DEBUG,
+			"failed to kick guest, virtqueue busy.\n");
+		return -1;
+	}
 
 	if (vq_is_packed(dev))
 		vhost_vring_call_packed(dev, vq);
-- 
2.21.3