Re: [PATCH] wireguard/queueing: simplify wg_cpumask_next_online()

On Thu, Jun 05, 2025 at 01:33:19PM +0200, Jason A. Donenfeld wrote:
> On Thu, Jun 05, 2025 at 12:23:29AM -0400, Yury Norov wrote:
> > On Wed, Jun 04, 2025 at 07:36:55PM -0400, Yury Norov wrote:
> > > wg_cpumask_choose_online() opencodes cpumask_nth(). Use it and make the
> > > function significantly simpler. While there, fix opencoded cpu_online()
> > > too. 
> > > 
> > > Signed-off-by: Yury Norov <[email protected]>
> > > ---
> > >  drivers/net/wireguard/queueing.h | 14 ++++----------
> > >  1 file changed, 4 insertions(+), 10 deletions(-)
> > > 
> > > diff --git a/drivers/net/wireguard/queueing.h b/drivers/net/wireguard/queueing.h
> > > index 7eb76724b3ed..3bfe16f71af0 100644
> > > --- a/drivers/net/wireguard/queueing.h
> > > +++ b/drivers/net/wireguard/queueing.h
> > > @@ -104,17 +104,11 @@ static inline void wg_reset_packet(struct sk_buff *skb, bool encapsulating)
> > >  
> > >  static inline int wg_cpumask_choose_online(int *stored_cpu, unsigned int id)
> > >  {
> > > -	unsigned int cpu = *stored_cpu, cpu_index, i;
> > > +	if (likely(*stored_cpu < nr_cpu_ids && cpu_online(*stored_cpu)))
> > > +		return cpu;
> > 
> > Oops... This should be 
> >                 return *stored_cpu;
> 
> Maybe it's best to structure the function something like:
> 
> unsigned int cpu = *stored_cpu;
> if (unlikely(cpu >= nr_cpu_ids || !cpu_online(cpu))) {
> 	cpu = *stored_cpu = cpumask_nth(id % num_online_cpus(),	cpu_online_mask);
> return cpu;

If you prefer. I'll send v2 shortly