linux-kernel - Re: [PATCH 03/14] sched rt,sysctl: remove proc input checks out of sysctl handlers

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Message-ID: <CACLa4ptMy0GkS=XSGVOPx4Ba2HN+N2EyK50BARr2xaOXfvDqcg@mail.gmail.com>
Date:	Sun, 29 Apr 2012 22:32:43 -0400
From:	Eric Paris <eparis@...isplace.org>
To:	Sasha Levin <levinsasha928@...il.com>
Cc:	viro@...iv.linux.org.uk, rostedt@...dmis.org, fweisbec@...il.com,
	mingo@...hat.com, a.p.zijlstra@...llo.nl, paulus@...ba.org,
	acme@...stprotocols.net, james.l.morris@...cle.com,
	ebiederm@...ssion.com, akpm@...ux-foundation.org,
	tglx@...utronix.de, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	linux-security-module@...r.kernel.org
Subject: Re: [PATCH 03/14] sched rt,sysctl: remove proc input checks out of
 sysctl handlers

NAK

old_period = sysctl_sched_rt_period;

Doesn't make any sense in the callback, since you already updated
sysctl_sched_rt_period.

I'll leave the remainder of the series as an exercise for the reader.
But I get the feeling this isn't the only place where you are doing
things after the proc_dointvec() which must be done before.

-Eric

On Sun, Apr 29, 2012 at 2:45 AM, Sasha Levin <levinsasha928@...il.com> wrote:
> Simplify sysctl handler by removing user input checks and using the callback
> provided by the sysctl table.
>
> Signed-off-by: Sasha Levin <levinsasha928@...il.com>
> ---
>  include/linux/sched.h |    4 +---
>  kernel/sched/core.c   |   25 ++++++++++---------------
>  kernel/sysctl.c       |    6 ++++--
>  3 files changed, 15 insertions(+), 20 deletions(-)
>
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 722da9a..9509d80 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -2152,9 +2152,7 @@ static inline unsigned int get_sysctl_timer_migration(void)
>  extern unsigned int sysctl_sched_rt_period;
>  extern int sysctl_sched_rt_runtime;
>
> -int sched_rt_handler(struct ctl_table *table, int write,
> -               void __user *buffer, size_t *lenp,
> -               loff_t *ppos);
> +int sched_rt_handler(void);
>
>  #ifdef CONFIG_SCHED_AUTOGROUP
>  extern unsigned int sysctl_sched_autogroup_enabled;
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 477b998..ca4a806 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -7573,9 +7573,7 @@ static int sched_rt_global_constraints(void)
>  }
>  #endif /* CONFIG_RT_GROUP_SCHED */
>
> -int sched_rt_handler(struct ctl_table *table, int write,
> -               void __user *buffer, size_t *lenp,
> -               loff_t *ppos)
> +int sched_rt_handler(void)
>  {
>        int ret;
>        int old_period, old_runtime;
> @@ -7585,19 +7583,16 @@ int sched_rt_handler(struct ctl_table *table, int write,
>        old_period = sysctl_sched_rt_period;
>        old_runtime = sysctl_sched_rt_runtime;
>
> -       ret = proc_dointvec(table, write, buffer, lenp, ppos);
> -
> -       if (!ret && write) {
> -               ret = sched_rt_global_constraints();
> -               if (ret) {
> -                       sysctl_sched_rt_period = old_period;
> -                       sysctl_sched_rt_runtime = old_runtime;
> -               } else {
> -                       def_rt_bandwidth.rt_runtime = global_rt_runtime();
> -                       def_rt_bandwidth.rt_period =
> -                               ns_to_ktime(global_rt_period());
> -               }
> +       ret = sched_rt_global_constraints();
> +       if (ret) {
> +               sysctl_sched_rt_period = old_period;
> +               sysctl_sched_rt_runtime = old_runtime;
> +       } else {
> +               def_rt_bandwidth.rt_runtime = global_rt_runtime();
> +               def_rt_bandwidth.rt_period =
> +                       ns_to_ktime(global_rt_period());
>        }
> +
>        mutex_unlock(&mutex);
>
>        return ret;
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index 23f1ac6..fad9ff6 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -347,14 +347,16 @@ static struct ctl_table kern_table[] = {
>                .data           = &sysctl_sched_rt_period,
>                .maxlen         = sizeof(unsigned int),
>                .mode           = 0644,
> -               .proc_handler   = sched_rt_handler,
> +               .proc_handler   = proc_dointvec,
> +               .callback       = sched_rt_handler,
>        },
>        {
>                .procname       = "sched_rt_runtime_us",
>                .data           = &sysctl_sched_rt_runtime,
>                .maxlen         = sizeof(int),
>                .mode           = 0644,
> -               .proc_handler   = sched_rt_handler,
> +               .proc_handler   = proc_dointvec,
> +               .callback       = sched_rt_handler,
>        },
>  #ifdef CONFIG_SCHED_AUTOGROUP
>        {
> --
> 1.7.8.5
>
> --
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