linux-kernel - Re: [PATCH] locking/percpu-rwsem: Add DEFINE_PERCPU_RWSEM(), use it to initialize cgroup_threadgroup

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Date:   Wed, 24 Apr 2019 11:34:59 -0700
From:   "Paul E. McKenney" <paulmck@...ux.ibm.com>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     Oleg Nesterov <oleg@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Tejun Heo <tj@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] locking/percpu-rwsem: Add DEFINE_PERCPU_RWSEM(), use it
 to initialize cgroup_threadgroup_rwsem

On Wed, Apr 24, 2019 at 01:02:56PM +0200, Ingo Molnar wrote:
> 
> * Oleg Nesterov <oleg@...hat.com> wrote:
> 
> > On 04/24, Ingo Molnar wrote:
> > >
> > > > -#define DEFINE_STATIC_PERCPU_RWSEM(name)				\
> > > > +#define __DEFINE_PERCPU_RWSEM(name, is_static)				\
> > > >  static DEFINE_PER_CPU(unsigned int, __percpu_rwsem_rc_##name);		\
> > > > -static struct percpu_rw_semaphore name = {				\
> > > > +is_static struct percpu_rw_semaphore name = {				\
> > > >  	.rss = __RCU_SYNC_INITIALIZER(name.rss),			\
> > > >  	.read_count = &__percpu_rwsem_rc_##name,			\
> > > >  	.rw_sem = __RWSEM_INITIALIZER(name.rw_sem),			\
> > > >  	.writer = __RCUWAIT_INITIALIZER(name.writer),			\
> > > >  }
> > > > +#define DEFINE_PERCPU_RWSEM(name)		\
> > > > +	__DEFINE_PERCPU_RWSEM(name, /* not static */)
> > > > +#define DEFINE_STATIC_PERCPU_RWSEM(name)	\
> > > > +	__DEFINE_PERCPU_RWSEM(name, static)
> > >
> > > Which tree is this against? It doesn't apply to tip:master nor latest
> > 
> > OOPS, sorry Ingo!
> > 
> > I forgot that the change above depends on another cleanup I sent to Paul,
> > 
> > 	[PATCH] rcu/sync: kill rcu_sync_type/gp_type
> > 	https://lore.kernel.org/lkml/20190423120724.GA6132@redhat.com/
> > 
> > which does
> > 
> > 	-       .rss = __RCU_SYNC_INITIALIZER(name.rss, RCU_SCHED_SYNC),        \
> > 	+       .rss = __RCU_SYNC_INITIALIZER(name.rss),                        \
> > 
> > so lets forget it for now, or may be Paul can take this patch too.
> 
> No problem, and both rwsem patches you sent seem fine to me:
> 
> Reviewed-by: Ingo Molnar <mingo@...nel.org>

I queued patches with Ingo's reviewed-by.  Thank you both!

							Thanx, Paul