Re: [PATCH v3] mm/kfence: print disabling or re-enabling message

[Marco Elver <elver@google.com>]

On Wed, 18 May 2022 at 03:03, Jackie Liu <liu.yun@linux.dev> wrote:
>
> From: Jackie Liu <liuyun01@kylinos.cn>
>
> By printing information, we can friendly prompt the status change
> information of kfence by dmesg and record by syslog.
>
> Co-developed-by: Marco Elver <elver@google.com>
> Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
> ---
>  v1->v2:
>    fixup by Marco Elver <elver@google.com>
>  v2->v3:
>    write kfence_enabled=false only true before
>
>  mm/kfence/core.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/mm/kfence/core.c b/mm/kfence/core.c
> index 11a954763be9..41840b8d9cb3 100644
> --- a/mm/kfence/core.c
> +++ b/mm/kfence/core.c
> @@ -67,8 +67,13 @@ static int param_set_sample_interval(const char *val, const struct kernel_param
>         if (ret < 0)
>                 return ret;
>
> -       if (!num) /* Using 0 to indicate KFENCE is disabled. */
> -               WRITE_ONCE(kfence_enabled, false);
> +       /* Using 0 to indicate KFENCE is disabled. */
> +       if (!num) {
> +               if (READ_ONCE(kfence_enabled)) {

Now you could just write

  if (!num && READ_ONCE(kfence_enabled)) {
    ....

> +                       pr_info("disabled\n");
> +                       WRITE_ONCE(kfence_enabled, false);
> +               }
> +       }
>
>         *((unsigned long *)kp->arg) = num;
>
> @@ -874,6 +879,7 @@ static int kfence_enable_late(void)
>
>         WRITE_ONCE(kfence_enabled, true);
>         queue_delayed_work(system_unbound_wq, &kfence_timer, 0);
> +       pr_info("re-enabled\n");
>         return 0;
>  }
>
> --
> 2.25.1
>