linux-kernel - Re: linux-next: build warning after merge of the v4l-dvb tree

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Message-ID: <20210215112024.22ebdd4c@coco.lan>
Date:   Mon, 15 Feb 2021 11:20:24 +0100
From:   Mauro Carvalho Chehab <mchehab@...nel.org>
To:     Ezequiel Garcia <ezequiel@...labora.com>
Cc:     Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux Next Mailing List <linux-next@...r.kernel.org>
Subject: Re: linux-next: build warning after merge of the v4l-dvb tree

Em Mon, 08 Feb 2021 15:53:00 -0300
Ezequiel Garcia <ezequiel@...labora.com> escreveu:

> On Mon, 2021-02-08 at 18:40 +0100, Mauro Carvalho Chehab wrote:
> > Em Mon, 08 Feb 2021 13:57:56 -0300
> > Ezequiel Garcia <ezequiel@...labora.com> escreveu:
> >   
> > > On Mon, 2021-02-08 at 18:46 +0200, Sakari Ailus wrote:  
> > > > Hi Ezequiel,
> > > > 
> > > > Thanks for addressing this.
> > > > 
> > > > On Mon, Feb 08, 2021 at 01:42:21PM -0300, Ezequiel Garcia wrote:    
> > > > > Hi Stephen,
> > > > > 
> > > > > On Mon, 2021-02-08 at 23:37 +1100, Stephen Rothwell wrote:    
> > > > > > Hi all,
> > > > > > 
> > > > > > After merging the v4l-dvb tree, today's linux-next build (htmldocs)
> > > > > > produced this warning:
> > > > > > 
> > > > > > include/media/v4l2-async.h:178: warning: expecting prototype for v4l2_async_notifier_add_fwnode_subdev(). Prototype was for
> > > > > > __v4l2_async_notifier_add_fwnode_subdev() instead
> > > > > > include/media/v4l2-async.h:207: warning: expecting prototype for v4l2_async_notifier_add_fwnode_remote_subdev(). Prototype was for
> > > > > > __v4l2_async_notifier_add_fwnode_remote_subdev() instead
> > > > > > include/media/v4l2-async.h:230: warning: expecting prototype for v4l2_async_notifier_add_i2c_subdev(). Prototype was for
> > > > > > __v4l2_async_notifier_add_i2c_subdev() instead
> > > > > > 
> > > > > > Maybe introduced by commit
> > > > > > 
> > > > > >   c1cc23625062 ("media: v4l2-async: Discourage use of v4l2_async_notifier_add_subdev")
> > > > > >     
> > > > > 
> > > > > Thanks for spotting this. Should be fixed by:
> > > > > 
> > > > > diff --git a/include/media/v4l2-async.h b/include/media/v4l2-async.h
> > > > > index 6f22daa6f067..3785445282fc 100644
> > > > > --- a/include/media/v4l2-async.h
> > > > > +++ b/include/media/v4l2-async.h
> > > > > @@ -157,7 +157,7 @@ int __v4l2_async_notifier_add_subdev(struct v4l2_async_notifier *notifier,
> > > > >                                    struct v4l2_async_subdev *asd);
> > > > >  
> > > > >  /**
> > > > > - * v4l2_async_notifier_add_fwnode_subdev - Allocate and add a fwnode async
> > > > > + * __v4l2_async_notifier_add_fwnode_subdev - Allocate and add a fwnode async    
> > > > 
> > > > The problem with the approach is that this no longer documents the API that
> > > > drivers are intended to use, but the intermediate one.  
> > 
> > Yep. the better would be to keep documenting what will be used.
> >   
> 
> Is there a way to silence/ignore the warning for a specific function(s)?

No. The warning is there for a very good reason: if you do something like:


	/**
	 * delete - delete some file
	 *
	 * This function deletes something.
	 */
	void insert() {}
	/**
	 * insert - creates a new file
	 *
	 * This function creates a file and inserts something.
	 */
	void delete() {}

the output of it will be:

	$ ./scripts/kernel-doc -sphinx-version 3.0.0 silly.c
	.. c:function:: void insert ()
	
	   delete some file
	
	**Parameters**
	
	**Description**
	
	
	This function deletes something.
	
	
	.. c:function:: void delete ()
	
	   creates a new file
	
	**Parameters**
	
	**Description**
	
	
	This function creates a file and inserts something.

Which is completely wrong. If someone tries to write a code using the
above, the result will be just the opposite than what it was documented.

Btw, I noticed several places where things like that happened, because
some code were added between a Kernel-doc markup and some function.

Thanks,
Mauro