linux-kernel - Re: [PATCH] USB: output an error message when the pipe type doesn't match the endpoint type

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Message-ID: <4C7FDABA.7080307@simon.arlott.org.uk>
Date:	Thu, 02 Sep 2010 18:11:22 +0100
From:	Simon Arlott <simon@...e.lp0.eu>
To:	Alan Stern <stern@...land.harvard.edu>
CC:	Greg KH <greg@...ah.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	USB list <linux-usb@...r.kernel.org>
Subject: Re: [PATCH] USB: output an error message when the pipe type  doesn't
 match the endpoint type

On 02/09/10 15:22, Alan Stern wrote:
> On Thu, 2 Sep 2010, Simon Arlott wrote:
> 
>> On Wed, September 1, 2010 18:49, Alan Stern wrote:
>> > On Wed, 1 Sep 2010, Simon Arlott wrote:
>> >> > This is okay with me.  If you're serious about not changing the
>> >> > behavior merely because debugging is enabled, you could move this test
>> >> > out of the debug-only region and possibly change the dev_err to
>> >> > dev_dbg.  However doing so might break some devices that are currently
>> >> > working.
> 
> Which suggests that the best approach is to print the error message 
> always, but allow the submission unless CONFIG_USB_DEBUG is set.

That could result in a lot of error messages, and it doesn't give any
information on which driver caused it, but a single WARN_ON() would
only be triggered once globally. Each USB device (or endpoint) could
have a "warned" flag.

>> Looking at usb_clear_halt(), it doesn't use the direction either... but
>> drivers can call it in both directions. Several drivers already do this.
> 
> What do you mean?  Look at the first lines of code in usb_clear_halt():
> 
> 	if (usb_pipein(pipe))
> 		endp |= USB_DIR_IN;

Sorry, I misread it as always selecting the same direction.

-- 
Simon Arlott
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