[PATCH] vhost: fix VDUSE devices registration

[PATCH] vhost: fix VDUSE devices registration

[Maxime Coquelin]

This patch fixes a regression in vhost_driver_register()
causing VDUSE devices registration to fail systematically
because the return value was initialized to -1 and not
changed later on for this type of devices.

Fixes: 4d2aa150769b ("vhost: remove check around mutex init")

Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
---
 lib/vhost/socket.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/lib/vhost/socket.c b/lib/vhost/socket.c
index 433a42bf80..894a0f0dcb 100644
--- a/lib/vhost/socket.c
+++ b/lib/vhost/socket.c
@@ -893,7 +893,6 @@ vhost_user_socket_mem_free(struct vhost_user_socket *vsocket)
 int
 rte_vhost_driver_register(const char *path, uint64_t flags)
 {
-	int ret = -1;
 	struct vhost_user_socket *vsocket;
 
 	if (!path)
@@ -997,7 +996,6 @@ rte_vhost_driver_register(const char *path, uint64_t flags)
 	} else {
 #ifndef RTE_LIBRTE_VHOST_POSTCOPY
 		VHOST_CONFIG_LOG(path, ERR, "Postcopy requested but not compiled");
-		ret = -1;
 		goto out_mutex;
 #endif
 	}
@@ -1012,15 +1010,14 @@ rte_vhost_driver_register(const char *path, uint64_t flags)
 		} else {
 			vsocket->is_server = true;
 		}
-		ret = create_unix_socket(vsocket);
-		if (ret < 0)
+		if (create_unix_socket(vsocket) < 0)
 			goto out_mutex;
 	}
 
 	vhost_user.vsockets[vhost_user.vsocket_cnt++] = vsocket;
 
 	pthread_mutex_unlock(&vhost_user.mutex);
-	return ret;
+	return 0;
 
 out_mutex:
 	if (pthread_mutex_destroy(&vsocket->conn_mutex)) {
@@ -1028,8 +1025,7 @@ rte_vhost_driver_register(const char *path, uint64_t flags)
 	}
 out:
 	pthread_mutex_unlock(&vhost_user.mutex);
-
-	return ret;
+	return -1;
 }
 
 static bool
-- 
2.48.1

Re: [PATCH] vhost: fix VDUSE devices registration

[Ariel Otilibili-Anieli]

Hello Maxime,

On Friday, January 31, 2025 14:09 CET, Maxime Coquelin <maxime.coquelin@redhat.com> wrote:

> This patch fixes a regression in vhost_driver_register()
> causing VDUSE devices registration to fail systematically
> because the return value was initialized to -1 and not
> changed later on for this type of devices.
> 
> Fixes: 4d2aa150769b ("vhost: remove check around mutex init")

Thanks for the heads up. I indeed committed 4d2aa150769b ("vhost: remove check around mutex init"); and it contained a hunk for vhost_driver_register().

I applied this patch against the tip of the main; from what I saw, there is no overlap with 4d2aa150769b ("vhost: remove check around mutex init").

It looks 4d2aa150769b ("vhost: remove check around mutex init") came up first, because I was the last person who edited the file.

The tags should be rather these ones:

Fixes: 0adb8eccc6a6 ("vhost: add VDUSE device creation and destruction")
Fixes: 78b2e3bae1af ("vhost: fix initialization")
Fixes: 64ab701c3d1e ("vhost: add vhost-user client mode")
Fixes: 8f972312b8f4 ("vhost: support vhost-user")

Does my reasoning make sense? Let me know.

:) For my understanding; now that 4d2aa150769b ("vhost: remove check around mutex init") needs a fix, is there a way by which I could have detect the regression?

Your help will be much appreciated,
Ariel