From mboxrd@z Thu Jan  1 00:00:00 1970
From: Li Zefan <lizf.kern@gmail.com>
Subject: Re: [PATCH 1/3] cgroup - removing superfluous rcu_read_lock_held
 check
Date: Wed, 03 Nov 2010 01:54:55 +0800
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To: Jiri Olsa <jolsa@redhat.com>
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On 2010=E5=B9=B411=E6=9C=8802=E6=97=A5 03:15, Jiri Olsa wrote:
> hi,

This..

> the rcu_dereference_check is defined as
>=20
> 	#define rcu_dereference_check(p, c) \
> 	   __rcu_dereference_check((p), rcu_read_lock_held() || (c), __rcu)
>=20
> so the caller does not need to specify rcu_read_lock_held() condition=
=2E
>
=20
> wbr,
> jirka

and this should be excluded from the changelog.

>=20
>=20
> Signed-off-by: Jiri Olsa <jolsa@redhat.com>

Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>

However a nitpick:

> ---
>  include/linux/cgroup.h |    1 -
>  kernel/cgroup.c        |    6 ++----
>  2 files changed, 2 insertions(+), 5 deletions(-)
=2E..
> @@ -4544,7 +4542,7 @@ unsigned short css_id(struct cgroup_subsys_stat=
e *css)
>  	 * it's unchanged until freed.
>  	 */
>  	cssid =3D rcu_dereference_check(css->id,
> -			rcu_read_lock_held() || atomic_read(&css->refcnt));
> +			atomic_read(&css->refcnt));

Now the 2 lines can be made into one line and still fit into 80 chars.

> =20
>  	if (cssid)
>  		return cssid->id;
> @@ -4557,7 +4555,7 @@ unsigned short css_depth(struct cgroup_subsys_s=
tate *css)
>  	struct css_id *cssid;
> =20
>  	cssid =3D rcu_dereference_check(css->id,
> -			rcu_read_lock_held() || atomic_read(&css->refcnt));
> +			atomic_read(&css->refcnt));

dito

> =20
>  	if (cssid)
>  		return cssid->depth;