Re: [PATCH v0 25/42] arch/um: Check notifier registration return value

[Johannes Berg]

On Mon, 2021-11-08 at 11:11 +0100, Borislav Petkov wrote:
> From: Borislav Petkov <bp@xxxxxxx>
> 
> Avoid homegrown notifier registration checks.
> 
> No functional changes.
> 
> Signed-off-by: Borislav Petkov <bp@xxxxxxx>
> Cc: linux-um@xxxxxxxxxxxxxxxxxxx
> ---
>  arch/um/drivers/mconsole_kern.c | 6 ++++--
>  arch/um/kernel/um_arch.c        | 5 +++--
>  2 files changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/um/drivers/mconsole_kern.c b/arch/um/drivers/mconsole_kern.c
> index 6ead1e240457..ceea940c0aa0 100644
> --- a/arch/um/drivers/mconsole_kern.c
> +++ b/arch/um/drivers/mconsole_kern.c
> @@ -856,8 +856,10 @@ static struct notifier_block panic_exit_notifier = {
>  
> 
>  static int add_notifier(void)
>  {
> -	atomic_notifier_chain_register(&panic_notifier_list,
> -			&panic_exit_notifier);
> +	if (atomic_notifier_chain_register(&panic_notifier_list,
> +					   &panic_exit_notifier))
> +		pr_warn("UM console panic notifier already registered\n");
> +
>  	return 0;

Maybe it should just return it? I don't see how this is ever possible,
since it's an initcall.

johannes