Re: [PATCH] checkpatch: Error out if deprecated RCU API used

[Joe Perches]

On Mon, 2023-03-06 at 22:10 -0500, Joel Fernandes wrote:
> On Mon, Mar 6, 2023 at 10:08 PM Joe Perches <joe@xxxxxxxxxxx> wrote:
> > 
> > On Tue, 2023-03-07 at 03:04 +0000, Joel Fernandes (Google) wrote:
> > > Single-argument kvfree_rcu() usage is being deprecated [1] [2] as it is
> > > error-prone. However, till all users are converted, we would like to introduce
> > > checkpatch errors for new patches submitted.
> > > 
> > > This patch adds support for the same. Tested with a trial patch.
> > > 
> > > For now, we are only considering usages that don't have compound
> > > nesting, for example ignore: kvfree_rcu( (rcu_head_obj), rcu_head_name).
> > > This is sufficient as such usages are unlikely.
> > > 
> > > Once all users are converted and we remove the old API, we can also revert this
> > > checkpatch patch then.
> > 
> > I think this should be added to the deprecated_apis hash instead
> > 
> > our %deprecated_apis = (
> >         "synchronize_rcu_bh"                    => "synchronize_rcu",
> >         "synchronize_rcu_bh_expedited"          => "synchronize_rcu_expedited",
> >         "call_rcu_bh"                           => "call_rcu",
> >         "rcu_barrier_bh"                        => "rcu_barrier",
> >         "synchronize_sched"                     => "synchronize_rcu",
> >         "synchronize_sched_expedited"           => "synchronize_rcu_expedited",
> >         "call_rcu_sched"                        => "call_rcu",
> >         "rcu_barrier_sched"                     => "rcu_barrier",
> >         "get_state_synchronize_sched"           => "get_state_synchronize_rcu",
> >         "cond_synchronize_sched"                => "cond_synchronize_rcu",
> >         "kmap"                                  => "kmap_local_page",
> >         "kunmap"                                => "kunmap_local",
> >         "kmap_atomic"                           => "kmap_local_page",
> >         "kunmap_atomic"                         => "kunmap_local",
> > );
> 
> This is not an API name change though, it is a "number of arguments"
> or argument list change. Is there a different way to do it?

Ah, no, not really.

btw: I don't see a single use of this call without a comma in the tree.