Re: kerneldoc warnings since commit 538fc2ee870a3 ("rcu: Introduce kfree_rcu() single-argument macro")

[Lukas Bulwahn]

On Tue, Jan 5, 2021 at 5:29 PM Uladzislau Rezki <urezki@xxxxxxxxx> wrote:
>
> On Tue, Jan 05, 2021 at 06:56:59AM -0800, Paul E. McKenney wrote:
> > On Tue, Jan 05, 2021 at 02:14:41PM +0100, Uladzislau Rezki wrote:
> > > Dear, Lukas.
> > >
> > > > Dear Uladzislau,
> > > >
> > > > in commit 538fc2ee870a3 ("rcu: Introduce kfree_rcu() single-argument
> > > > macro"), you have refactored the kfree_rcu macro.
> > > >
> > > > Since then, make htmldocs warns:
> > > >
> > > > ./include/linux/rcupdate.h:882: warning: Excess function parameter
> > > > 'ptr' description in 'kfree_rcu'
> > > > ./include/linux/rcupdate.h:882: warning: Excess function parameter
> > > > 'rhf' description in 'kfree_rcu'
> > > >
> > > > As you deleted the two arguments in the macro definition, kerneldoc
> > > > cannot resolve the argument names in the macro's kerneldoc
> > > > documentation anymore and warns about that.
> > > >
> > > > Probably, it is best to just turn the formal kerneldoc references to
> > > > the two arguments, which are not used in the macro definition anymore,
> > > > simply into two informal references in the documentation.
> > > >
> > > Thanks for your suggestion. I am not sure if htmldocs supports something
> > > like "__maybe_unused", but tend to say that it does not. See below the
> > > patch:
> > >
> > > <snip>
> > > >From 65ecc7c58810c963c02e0596ce2e5758c54ef55d Mon Sep 17 00:00:00 2001
> > > From: "Uladzislau Rezki (Sony)" <urezki@xxxxxxxxx>
> > > Date: Tue, 5 Jan 2021 13:23:30 +0100
> > > Subject: [PATCH] rcu: fix kerneldoc warnings
> > >
> > > After refactoring of the kfree_rcu(), it becomes possible to use
> > > the macro with one or two arguments. From the other hand, in the
> > > description there are two arguments in the macro definition expected.
> > > That is why the "htmldocs" emits a warning about it:
> > >
> > > <snip>
> > > ./include/linux/rcupdate.h:882: warning: Excess function parameter
> > > 'ptr' description in 'kfree_rcu'
> > > ./include/linux/rcupdate.h:882: warning: Excess function parameter
> > > 'rhf' description in 'kfree_rcu'
> > > <snip>
> > >
> > > Fix it by converting two parameters into informal references in the
> > > macro description.
> > >
> > > Fixes: 3d3d9ff077a9 ("rcu: Introduce kfree_rcu() single-argument macro")
> > > Signed-off-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx>
> > > ---
> > >  include/linux/rcupdate.h | 4 ++--
> > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
> > > index ebd8dcca4997..e678ce7f5ca2 100644
> > > --- a/include/linux/rcupdate.h
> > > +++ b/include/linux/rcupdate.h
> > > @@ -854,8 +854,8 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
> > >
> > >  /**
> > >   * kfree_rcu() - kfree an object after a grace period.
> > > - * @ptr: pointer to kfree for both single- and double-argument invocations.
> > > - * @rhf: the name of the struct rcu_head within the type of @ptr,
> > > + * ptr: pointer to kfree for both single- and double-argument invocations.
> > > + * rhf: the name of the struct rcu_head within the type of ptr,
> > >   *       but only for double-argument invocations.
> > >   *
> > >   * Many rcu callbacks functions just call kfree() on the base structure.
> > > --
> > > 2.20.1
> > > <snip>
> > >
> > > Paul, does it work for you?
> >
> > If it works for the documentation generation, then it works for me.  ;-)
> >
> OK. Then we need the patch to be reviewed by the documentation generation :)
>
> Dear, linux-doc folk!
>
> Could you please review the patch that is in question?
>

I think you can shorten the feedback loop.
IMHO, the documentation is as comprehensible as before and it makes a
warning go away (getting us back to the zero-documentation-warnings
state).

Just send out your patch with linux-doc as CC and if there is no
complaint within a few days, Paul will pick it up and it is all good.

Lukas