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 12:31:55 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Oleg Nesterov <oleg@...hat.com>
Cc:     "Paul E. McKenney" <paulmck@...ux.ibm.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


* Oleg Nesterov <oleg@...hat.com> wrote:

> Turn DEFINE_STATIC_PERCPU_RWSEM() into __DEFINE_PERCPU_RWSEM() with the
> additional "is_static" argument to introduce DEFINE_PERCPU_RWSEM().
> 
> Change cgroup.c to use DEFINE_PERCPU_RWSEM(cgroup_threadgroup_rwsem).
> 
> Signed-off-by: Oleg Nesterov <oleg@...hat.com>
> ---
>  include/linux/percpu-rwsem.h | 8 ++++++--
>  kernel/cgroup/cgroup.c       | 3 +--
>  2 files changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/include/linux/percpu-rwsem.h b/include/linux/percpu-rwsem.h
> index 6887636..2809b44 100644
> --- a/include/linux/percpu-rwsem.h
> +++ b/include/linux/percpu-rwsem.h
> @@ -17,14 +17,18 @@ struct percpu_rw_semaphore {
>  	int			readers_block;
>  };
>  
> -#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 
-git.

Thanks,

	Ingo