linux-kernel - RE: [char-misc 1/2 4.3 V2] mei: Fix debugfs filename in error output

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Date:	Tue, 6 Oct 2015 08:46:32 +0000
From:	"Winkler, Tomas" <tomas.winkler@...el.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:	"Usyskin, Alexander" <alexander.usyskin@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Alexander Kuleshov" <kuleshovmail@...il.com>
Subject: RE: [char-misc 1/2 4.3 V2] mei: Fix debugfs filename in error output

> > > >  		goto err;
> > >
> > > You should never care if a debugfs call fails or not.
> >
> > The system should not be dependent on the debug feature but, it is
> > always good to know if there our system is failing
> 
> And what can you do if it is "failing"?  Really nothing, so there's
> nothing to check here.

As far as I can see the function debugfs_create_file may fail for a few reasons and it return  NULL if this is happening.
I might ignore the error as you suggested, but I'm not sure why not to give a hint in log that this happened. 
Second, as far as I scanned the kernel sources, checking the return value of this function and acting on this is very common.

> >   Also, this will
> > > "fail" if you don't have CONFIG_DEBUGFS enabled, which means you are
> > > using the api wrong :(
> >
> > The whole file is not compiled if CONFIG_DEBUGFS is not set, please see the
> Makefile
> 
> Ok, then you don't need to check anything.  Debugfs was created to be
> dirt-simple, don't add complexity and "must unwind cleanly" type logic
> here where it's not needed at all.  That just hurts my sensibilities for
> why I made the API the way it is in the first place :)

I don't see the code much complex, it is pretty much boilerplate code and this is why this c&p error had happened. 
So this patch just fixes a c&p error in an error message and if we wish to change the behavior to match your vision 
I suggest to doing it another patch set... maybe even sweeping the whole kernel. 

Thanks
Tomas 

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