Re: [PATCH] sched/debug: remove obsolete init_schedstats()

From: Kees Cook
Date: Wed Jun 02 2021 - 13:46:26 EST


On Wed, Jun 02, 2021 at 04:21:08AM -0700, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@xxxxxxxxxx>
>
> Revert "sched/debug: Fix 'schedstats=enable' cmdline option"
>
> This reverts commit 4698f88c06b893f2acc0b443004a53bf490fde7c.
>
> After commit 6041186a3258 ("init: initialize jump labels before command
> line option parsing") we can rely on jump label infra being ready for use
> when setup_schedstats() is called.

Ah yeah, good catch.

Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>

-Kees

>
> Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
> Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> Cc: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
> Cc: Guenter Roeck <groeck@xxxxxxxxxx>
> Cc: Kees Cook <keescook@xxxxxxxxxxxx>
> ---
> kernel/sched/core.c | 19 ++-----------------
> 1 file changed, 2 insertions(+), 17 deletions(-)
>
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 5226cc26a095f427dafa864ff37d39d529e2ba85..105fa6c73e7d9ded05683ee43a11e3b4461932d5 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -3648,7 +3648,6 @@ int sysctl_numa_balancing(struct ctl_table *table, int write,
> #ifdef CONFIG_SCHEDSTATS
>
> DEFINE_STATIC_KEY_FALSE(sched_schedstats);
> -static bool __initdata __sched_schedstats = false;
>
> static void set_schedstats(bool enabled)
> {
> @@ -3672,16 +3671,11 @@ static int __init setup_schedstats(char *str)
> if (!str)
> goto out;
>
> - /*
> - * This code is called before jump labels have been set up, so we can't
> - * change the static branch directly just yet. Instead set a temporary
> - * variable so init_schedstats() can do it later.
> - */
> if (!strcmp(str, "enable")) {
> - __sched_schedstats = true;
> + set_schedstats(true);
> ret = 1;
> } else if (!strcmp(str, "disable")) {
> - __sched_schedstats = false;
> + set_schedstats(false);
> ret = 1;
> }
> out:
> @@ -3692,11 +3686,6 @@ static int __init setup_schedstats(char *str)
> }
> __setup("schedstats=", setup_schedstats);
>
> -static void __init init_schedstats(void)
> -{
> - set_schedstats(__sched_schedstats);
> -}
> -
> #ifdef CONFIG_PROC_SYSCTL
> int sysctl_schedstats(struct ctl_table *table, int write, void *buffer,
> size_t *lenp, loff_t *ppos)
> @@ -3718,8 +3707,6 @@ int sysctl_schedstats(struct ctl_table *table, int write, void *buffer,
> return err;
> }
> #endif /* CONFIG_PROC_SYSCTL */
> -#else /* !CONFIG_SCHEDSTATS */
> -static inline void init_schedstats(void) {}
> #endif /* CONFIG_SCHEDSTATS */
>
> /*
> @@ -8258,8 +8245,6 @@ void __init sched_init(void)
> #endif
> init_sched_fair_class();
>
> - init_schedstats();
> -
> psi_init();
>
> init_uclamp();
> --
> 2.32.0.rc0.204.g9fa02ecfa5-goog
>

--
Kees Cook