[PATCH] virtio_console: remove pointless check for debugfs_create_dir()

[PATCH] virtio_console: remove pointless check for debugfs_create_dir()

[Greg Kroah-Hartman]

It is impossible for debugfs_create_dir() to return NULL, so checking
for it gives people a false sense that they actually are doing something
if an error occurs.  As there is no need to ever change kernel logic if
debugfs is working "properly" or not, there is no need to check the
return value of debugfs calls, so remove the checks here as they will
never be triggered and are wrong.

Cc: Amit Shah <amit@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: virtualization@lists.linux-foundation.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/char/virtio_console.c | 23 +++++++++--------------
 1 file changed, 9 insertions(+), 14 deletions(-)

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 1836cc56e357..59dfd9c421a1 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -1456,18 +1456,15 @@ static int add_port(struct ports_device *portdev, u32 id)
 	 */
 	send_control_msg(port, VIRTIO_CONSOLE_PORT_READY, 1);
 
-	if (pdrvdata.debugfs_dir) {
-		/*
-		 * Finally, create the debugfs file that we can use to
-		 * inspect a port's state at any time
-		 */
-		snprintf(debugfs_name, sizeof(debugfs_name), "vport%up%u",
-			 port->portdev->vdev->index, id);
-		port->debugfs_file = debugfs_create_file(debugfs_name, 0444,
-							 pdrvdata.debugfs_dir,
-							 port,
-							 &port_debugfs_fops);
-	}
+	/*
+	 * Finally, create the debugfs file that we can use to
+	 * inspect a port's state at any time
+	 */
+	snprintf(debugfs_name, sizeof(debugfs_name), "vport%up%u",
+		 port->portdev->vdev->index, id);
+	port->debugfs_file = debugfs_create_file(debugfs_name, 0444,
+						 pdrvdata.debugfs_dir,
+						 port, &port_debugfs_fops);
 	return 0;
 
 free_inbufs:
@@ -2244,8 +2241,6 @@ static int __init init(void)
 	}
 
 	pdrvdata.debugfs_dir = debugfs_create_dir("virtio-ports", NULL);
-	if (!pdrvdata.debugfs_dir)
-		pr_warn("Error creating debugfs dir for virtio-ports\n");
 	INIT_LIST_HEAD(&pdrvdata.consoles);
 	INIT_LIST_HEAD(&pdrvdata.portdevs);
 
-- 
2.30.1

Re: [PATCH] virtio_console: remove pointless check for debugfs_create_dir()

[Amit Shah]

On Tue, 2021-02-16 at 16:04 +0100, Greg Kroah-Hartman wrote:
> It is impossible for debugfs_create_dir() to return NULL, so checking
> for it gives people a false sense that they actually are doing something
> if an error occurs.  As there is no need to ever change kernel logic if
> debugfs is working "properly" or not, there is no need to check the
> return value of debugfs calls, so remove the checks here as they will
> never be triggered and are wrong.
> 
> Cc: Amit Shah <amit@kernel.org>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: virtualization@lists.linux-foundation.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
>  drivers/char/virtio_console.c | 23 +++++++++--------------
>  1 file changed, 9 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
> index 1836cc56e357..59dfd9c421a1 100644
> --- a/drivers/char/virtio_console.c
> +++ b/drivers/char/virtio_console.c
> @@ -1456,18 +1456,15 @@ static int add_port(struct ports_device *portdev, u32 id)
>  	 */
>  	send_control_msg(port, VIRTIO_CONSOLE_PORT_READY, 1);
>  
> -	if (pdrvdata.debugfs_dir) {
> -		/*
> -		 * Finally, create the debugfs file that we can use to
> -		 * inspect a port's state at any time
> -		 */
> -		snprintf(debugfs_name, sizeof(debugfs_name), "vport%up%u",
> -			 port->portdev->vdev->index, id);
> -		port->debugfs_file = debugfs_create_file(debugfs_name, 0444,
> -							 pdrvdata.debugfs_dir,
> -							 port,
> -							 &port_debugfs_fops);
> -	}
> +	/*
> +	 * Finally, create the debugfs file that we can use to
> +	 * inspect a port's state at any time
> +	 */
> +	snprintf(debugfs_name, sizeof(debugfs_name), "vport%up%u",
> +		 port->portdev->vdev->index, id);
> +	port->debugfs_file = debugfs_create_file(debugfs_name, 0444,
> +						 pdrvdata.debugfs_dir,
> +						 port, &port_debugfs_fops);
>  	return 0;
>  
>  free_inbufs:
> @@ -2244,8 +2241,6 @@ static int __init init(void)
>  	}
>  
>  	pdrvdata.debugfs_dir = debugfs_create_dir("virtio-ports", NULL);
> -	if (!pdrvdata.debugfs_dir)
> -		pr_warn("Error creating debugfs dir for virtio-ports\n");
>  	INIT_LIST_HEAD(&pdrvdata.consoles);
>  	INIT_LIST_HEAD(&pdrvdata.portdevs);
> 

Reviewed-by: Amit Shah <amit@kernel.org>