linux-kernel - Re: [PATCH 2/4] mm/kasan: move kasan= code to common place

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Message-ID: <CANpmjNNr7e6DXQrZva8k46jELr1JSkjExWvQOyrkY5VD8mOadw@mail.gmail.com>
Date: Wed, 6 Aug 2025 09:11:05 +0200
From: Marco Elver <elver@...gle.com>
To: Baoquan He <bhe@...hat.com>
Cc: linux-mm@...ck.org, ryabinin.a.a@...il.com, glider@...gle.com, 
	andreyknvl@...il.com, dvyukov@...gle.com, vincenzo.frascino@....com, 
	akpm@...ux-foundation.org, kasan-dev@...glegroups.com, 
	linux-kernel@...r.kernel.org, kexec@...ts.infradead.org
Subject: Re: [PATCH 2/4] mm/kasan: move kasan= code to common place

On Tue, 5 Aug 2025 at 08:24, 'Baoquan He' via kasan-dev
<kasan-dev@...glegroups.com> wrote:
>
> This allows generic and sw_tags to be set in kernel cmdline too.
>
> When at it, rename 'kasan_arg' to 'kasan_arg_disabled' as a bool
> variable. And expose 'kasan_flag_enabled' to kasan common place
> too.
>
> This is prepared for later adding kernel parameter kasan=on|off for
> all kasan modes.
>
> Signed-off-by: Baoquan He <bhe@...hat.com>
> ---
>  include/linux/kasan-enabled.h |  4 +++-
>  mm/kasan/common.c             | 27 +++++++++++++++++++++++++++
>  mm/kasan/hw_tags.c            | 35 ++---------------------------------
>  3 files changed, 32 insertions(+), 34 deletions(-)
>
> diff --git a/include/linux/kasan-enabled.h b/include/linux/kasan-enabled.h
> index 6f612d69ea0c..32f2d19f599f 100644
> --- a/include/linux/kasan-enabled.h
> +++ b/include/linux/kasan-enabled.h
> @@ -4,10 +4,12 @@
>
>  #include <linux/static_key.h>
>
> -#ifdef CONFIG_KASAN_HW_TAGS
> +extern bool kasan_arg_disabled;
>
>  DECLARE_STATIC_KEY_FALSE(kasan_flag_enabled);
>
> +#ifdef CONFIG_KASAN_HW_TAGS
> +
>  static __always_inline bool kasan_enabled(void)
>  {
>         return static_branch_likely(&kasan_flag_enabled);
> diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> index ed4873e18c75..fe6937654203 100644
> --- a/mm/kasan/common.c
> +++ b/mm/kasan/common.c
> @@ -32,6 +32,33 @@
>  #include "kasan.h"
>  #include "../slab.h"
>
> +/*
> + * Whether KASAN is enabled at all.
> + * The value remains false until KASAN is initialized.
> + */
> +DEFINE_STATIC_KEY_FALSE(kasan_flag_enabled);
> +EXPORT_SYMBOL(kasan_flag_enabled);
> +
> +bool kasan_arg_disabled;

You lost __ro_after_init

> +/* kasan=off/on */
> +static int __init early_kasan_flag(char *arg)
> +{
> +       if (!arg)
> +               return -EINVAL;
> +
> +       if (!strcmp(arg, "off"))
> +               kasan_arg_disabled = true;
> +       else if (!strcmp(arg, "on"))
> +               kasan_arg_disabled = false;
> +       else
> +               return -EINVAL;
> +
> +       return 0;
> +}
> +early_param("kasan", early_kasan_flag);
> +
> +
> +

Why extra blank lines?