[PATCH] usb: core: usb_submit_urb: downgrade type check

[PATCH] usb: core: usb_submit_urb: downgrade type check

[Oliver Neukum]

Checking for the endpoint type is no reason for a WARN,
as that can cause a reboot. A driver not checking the
endpoint type must not cause a reboot, as there is just
no point in this.
We cannot prevent a device from doing something incorrect
as a reaction to a transfer. Hence warning for a mere
assumption being wrong is not sensible.

Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
 drivers/usb/core/urb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c
index 5e52a35486af..acf74ad36326 100644
--- a/drivers/usb/core/urb.c
+++ b/drivers/usb/core/urb.c
@@ -500,7 +500,7 @@ int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
 
 	/* Check that the pipe's type matches the endpoint's type */
 	if (usb_pipe_type_check(urb->dev, urb->pipe))
-		dev_WARN(&dev->dev, "BOGUS urb xfer, pipe %x != type %x\n",
+		dev_dbg(&dev->dev, "BOGUS urb xfer, pipe %x != type %x\n",
 			usb_pipetype(urb->pipe), pipetypes[xfertype]);
 
 	/* Check against a simple/standard policy */
-- 
2.49.0

Re: [PATCH] usb: core: usb_submit_urb: downgrade type check

[Alan Stern]

On Wed, Jun 11, 2025 at 03:52:25PM +0200, Oliver Neukum wrote:
> Checking for the endpoint type is no reason for a WARN,
> as that can cause a reboot. A driver not checking the
> endpoint type must not cause a reboot, as there is just
> no point in this.
> We cannot prevent a device from doing something incorrect
> as a reaction to a transfer. Hence warning for a mere
> assumption being wrong is not sensible.

Agreed.  On the other hand, we (or at least, I) don't want these 
messages to get lost because people haven't enabled dynamic debugging.
And even though we can't change the way the device behaves, we can alter 
the kernel's behavior.

How about using dev_warn_once() instead?

Alan Stern

> 
> Signed-off-by: Oliver Neukum <oneukum@suse.com>
> ---
>  drivers/usb/core/urb.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c
> index 5e52a35486af..acf74ad36326 100644
> --- a/drivers/usb/core/urb.c
> +++ b/drivers/usb/core/urb.c
> @@ -500,7 +500,7 @@ int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
>  
>  	/* Check that the pipe's type matches the endpoint's type */
>  	if (usb_pipe_type_check(urb->dev, urb->pipe))
> -		dev_WARN(&dev->dev, "BOGUS urb xfer, pipe %x != type %x\n",
> +		dev_dbg(&dev->dev, "BOGUS urb xfer, pipe %x != type %x\n",
>  			usb_pipetype(urb->pipe), pipetypes[xfertype]);
>  
>  	/* Check against a simple/standard policy */
> -- 
> 2.49.0
> 
>