Re: [PATCH] ftrace:fix check for return value of register_module_notifier

[Frederic Weisbecker <fweisbec@gmail.com>]

On Sun, May 17, 2009 at 03:31:38PM +0800, tom.leiming@gmail.com wrote:
> From: Ming Lei <tom.leiming@gmail.com>
> 
> return zero should be correct, so fix it.
> 
> Signed-off-by: Ming Lei <tom.leiming@gmail.com>
> ---
>  kernel/trace/ftrace.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index 5b606f4..140699a 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -2826,7 +2826,7 @@ void __init ftrace_init(void)
>  				  __stop_mcount_loc);
>  
>  	ret = register_module_notifier(&ftrace_module_nb);
> -	if (!ret)
> +	if (ret)
>  		pr_warning("Failed to register trace ftrace module notifier\n");
>  
>  	return;


Indeed!

register_module_notifier returns blocking_notifier_chain_register():

 *
 *	Currently always returns zero.
 */
int blocking_notifier_chain_register(struct blocking_notifier_head *nh,
		struct notifier_block *n)

For now it will never return anything else than 0 but we can keep
the warning in case it changes one day, as you did.

Acked-by: Frederic Weisbecker <fweisbec@gmail.com>