Subject: Re: [PATCH net] hsr: Handle failures in module init

From: Breno Leitao <[email-masked]>
Date: Thu, 14 Mar 2024 05:59:35 -0700

On Thu, Mar 14, 2024 at 11:10:52AM +0100, Felix Maurer wrote:
> A failure during registration of the netdev notifier was not handled at
> all. A failure during netlink initialization did not unregister the netdev
> notifier.
> 
> Handle failures of netdev notifier registration and netlink initialization.
> Both functions should only return negative values on failure and thereby
> lead to the hsr module not being loaded.
> 
> Signed-off-by: Felix Maurer <[email-masked]>
> ---
>  net/hsr/hsr_main.c | 18 ++++++++++++++----
>  1 file changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/net/hsr/hsr_main.c b/net/hsr/hsr_main.c
> index cb83c8feb746..1c4a5b678688 100644
> --- a/net/hsr/hsr_main.c
> +++ b/net/hsr/hsr_main.c
> @@ -148,14 +148,24 @@ static struct notifier_block hsr_nb = {
>  
>  static int __init hsr_init(void)
>  {
> -	int res;
> +	int err;
>  
>  	BUILD_BUG_ON(sizeof(struct hsr_tag) != HSR_HLEN);
>  
> -	register_netdevice_notifier(&hsr_nb);
> -	res = hsr_netlink_init();
> +	err = register_netdevice_notifier(&hsr_nb);
> +	if (err)
> +		goto out;

Can't you just 'return err' here? And avoid the `out` label below?

> +
> +	err = hsr_netlink_init();
> +	if (err)
> +		goto cleanup;

Same here, you can do something like the following and remove the
all the labels below, making the function a bit clearer.

	if (err) {
		unregister_netdevice_notifier(&hsr_nb);
		return err;
	}