linux-kernel - Re: [PATCH 1/2]drivers/usb/core/sysfs.c Fix variable 'retval' set but not used

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Date:	Tue, 3 Aug 2010 10:29:52 -0400 (EDT)
From:	Alan Stern <stern@...land.harvard.edu>
To:	Valdis.Kletnieks@...edu
cc:	"Justin P. Mattock" <justinmattock@...il.com>,
	<linux-usb@...r.kernel.org>, <dbrownell@...rs.sourceforge.net>,
	<gregkh@...e.de>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2]drivers/usb/core/sysfs.c Fix variable 'retval' set
 but not used

On Tue, 3 Aug 2010 Valdis.Kletnieks@...edu wrote:

> On Mon, 02 Aug 2010 21:26:28 PDT, "Justin P. Mattock" said:
> > diff --git a/drivers/usb/core/sysfs.c b/drivers/usb/core/sysfs.c
> 
> >  	if (alt->string)
> > -		retval = device_create_file(&intf->dev, &dev_attr_interface);
> > +		device_create_file(&intf->dev, &dev_attr_interface);
> >  	intf->sysfs_files_created = 1;
> >  	return 0;

Justin, did you try compiling your new code?  Those unused values are 
there because device_create_file is declared as __must_check.

> What should the code do if device_create_file() manages to fail? Yes, ignoring
> the return value is one option, but is it the best one?  'return ret;' might be
> another one. Somebody who understands this code and has more caffeine than me
> should look this over.

Failure to create a file in sysfs is almost never fatal and usually not 
even dangerous.  Ignoring the error is generally better than failing 
the entire operation.

Alan Stern

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