Re: [PATCH RESUBMIT 1/2] fs/seq_file: Create new function seq_open_init()

[Rob Jones]

On 24/09/14 22:39, Andrew Morton wrote:
> On Wed, 24 Sep 2014 12:15:55 +0100 Rob Jones <rob.jones@xxxxxxxxxxxxxxx> wrote:
>
> > Add a new function to help reduce boilerplate code.
> >
> > This is a wrapper function for seq_open() that will simplify the code in a
> > significant number of cases where seq_open() is currently called.
> >
> > It's first use is in __seq_open_private(), thereby recovering most of
> > the code space used by the new function.
>
> It would be nice to include one or more of the conversions in this patch
> series so we can see what the effects look like.

There are certainly lots of candidates around. However, I thought that
the change to __seq_open_private() already gave a good illustration of
the level of savings to be made, in that it more or less made the new
function "self financing".

> > --- a/fs/seq_file.c
> > +++ b/fs/seq_file.c
> > @@ -639,28 +639,38 @@ int seq_release_private(struct inode *inode, struct file *file)
> >   }
> >   EXPORT_SYMBOL(seq_release_private);
> >
> > +int seq_open_init(struct file *f, const struct seq_operations *ops, void *p)
> > +{
> > +	struct seq_file *s;
> > +	int rc;
> > +
> > +	rc = seq_open(f, ops);
> > +	if (rc)
> > +		return rc;
> > +
> > +	s = f->private_data;
> > +	s->private = p;
> > +
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL(seq_open_init);
>
> A global exported-to-modules interface should be documented, please.
> Especially when it has a void* argument.  seq_file.c is patchy - some
> of it is documented, some of it uses the read-programmers-mind
> approach.

I have included documentation as the second patch. Would it have been
better to include them in a single patch? I didn't do that because
seq_file and Documentation have different maintainers. I'm still
learning the protocols here.

> __seq_open_private() has
> 	void *private;
>
> single_open() has
> 	void *data
>
> And now seq_open_init() has
> 	void *p
>
> but these all refer to the same thing.  Can we have a bit of
> consistency in the naming please?  I suggest "private", to match
> the seq_file field.

A valid point and I can easily make the change but fixing single_open()
would mean that the patch is addressing two issues, is that acceptable?
Another protocol question, sorry.

--
Rob Jones
Codethink Ltd
mailto:rob.jones@xxxxxxxxxxxxxxx
tel:+44 161 236 5575
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