[dpdk-dev] [PATCH v2 1/3] virtio-user: fix backend selection if stat fails

[Adrian Moreno <amorenoz@redhat.com>]

If stat fails because the file does not exist, it means that
the backend must be vhost-user in server mode.

Also, log the detected backend type.

Bugzilla ID: 559
Fixes: f908b22ea47a ("net/virtio: move backend type selection to ethdev")
Cc: stable@dpdk.org

Signed-off-by: Adrian Moreno <amorenoz@redhat.com>
---
 drivers/net/virtio/virtio_user/virtio_user_dev.c | 7 +++++++
 drivers/net/virtio/virtio_user/virtio_user_dev.h | 1 +
 drivers/net/virtio/virtio_user_ethdev.c          | 6 +++++-
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/net/virtio/virtio_user/virtio_user_dev.c b/drivers/net/virtio/virtio_user/virtio_user_dev.c
index 3681758ef..27814eadb 100644
--- a/drivers/net/virtio/virtio_user/virtio_user_dev.c
+++ b/drivers/net/virtio/virtio_user/virtio_user_dev.c
@@ -22,6 +22,13 @@
 
 #define VIRTIO_USER_MEM_EVENT_CLB_NAME "virtio_user_mem_event_clb"
 
+const char * const virtio_user_backend_strings[] = {
+	[VIRTIO_USER_BACKEND_UNKNOWN] = "VIRTIO_USER_BACKEND_UNKNOWN",
+	[VIRTIO_USER_BACKEND_VHOST_USER] = "VHOST_USER",
+	[VIRTIO_USER_BACKEND_VHOST_KERNEL] = "VHOST_NET",
+	[VIRTIO_USER_BACKEND_VHOST_VDPA] = "VHOST_VDPA",
+};
+
 static int
 virtio_user_create_queue(struct virtio_user_dev *dev, uint32_t queue_sel)
 {
diff --git a/drivers/net/virtio/virtio_user/virtio_user_dev.h b/drivers/net/virtio/virtio_user/virtio_user_dev.h
index 3e9d1a1eb..998986875 100644
--- a/drivers/net/virtio/virtio_user/virtio_user_dev.h
+++ b/drivers/net/virtio/virtio_user/virtio_user_dev.h
@@ -83,4 +83,5 @@ void virtio_user_handle_cq_packed(struct virtio_user_dev *dev,
 uint8_t virtio_user_handle_mq(struct virtio_user_dev *dev, uint16_t q_pairs);
 int virtio_user_send_status_update(struct virtio_user_dev *dev, uint8_t status);
 int virtio_user_update_status(struct virtio_user_dev *dev);
+extern const char * const virtio_user_backend_strings[];
 #endif
diff --git a/drivers/net/virtio/virtio_user_ethdev.c b/drivers/net/virtio/virtio_user_ethdev.c
index 042665bc0..e870fb2ff 100644
--- a/drivers/net/virtio/virtio_user_ethdev.c
+++ b/drivers/net/virtio/virtio_user_ethdev.c
@@ -560,6 +560,9 @@ virtio_user_backend_type(const char *path)
 	struct stat sb;
 
 	if (stat(path, &sb) == -1) {
+		if (errno == ENOENT)
+			return VIRTIO_USER_BACKEND_VHOST_USER;
+
 		PMD_INIT_LOG(ERR, "Stat fails: %s (%s)\n", path,
 			     strerror(errno));
 		return VIRTIO_USER_BACKEND_UNKNOWN;
@@ -697,7 +700,8 @@ virtio_user_pmd_probe(struct rte_vdev_device *dev)
 			path);
 		goto end;
 	}
-
+	PMD_INIT_LOG(INFO, "Backend type detected: %s",
+		     virtio_user_backend_strings[backend_type]);
 
 	if (rte_kvargs_count(kvlist, VIRTIO_USER_ARG_INTERFACE_NAME) == 1) {
 		if (backend_type != VIRTIO_USER_BACKEND_VHOST_KERNEL) {
-- 
2.26.2