Subject: Re: [PATCH net-next 02/15] net: dsa: sja1105: Remove usage of iterator for list_add() after loop

From: Jakub Kicinski <[email-masked]>
Date: Thu, 7 Apr 2022 20:54:26 -0700

On Thu,  7 Apr 2022 12:28:47 +0200 Jakob Koschel wrote:
> diff --git a/drivers/net/dsa/sja1105/sja1105_vl.c b/drivers/net/dsa/sja1105/sja1105_vl.c
> index b7e95d60a6e4..cfcae4d19eef 100644
> --- a/drivers/net/dsa/sja1105/sja1105_vl.c
> +++ b/drivers/net/dsa/sja1105/sja1105_vl.c
> @@ -27,20 +27,24 @@ static int sja1105_insert_gate_entry(struct sja1105_gating_config *gating_cfg,
>  	if (list_empty(&gating_cfg->entries)) {
>  		list_add(&e->list, &gating_cfg->entries);
>  	} else {
> -		struct sja1105_gate_entry *p;
> +		struct sja1105_gate_entry *p = NULL, *iter;
>  
> -		list_for_each_entry(p, &gating_cfg->entries, list) {
> -			if (p->interval == e->interval) {
> +		list_for_each_entry(iter, &gating_cfg->entries, list) {
> +			if (iter->interval == e->interval) {
>  				NL_SET_ERR_MSG_MOD(extack,
>  						   "Gate conflict");
>  				rc = -EBUSY;
>  				goto err;
>  			}
>  
> -			if (e->interval < p->interval)
> +			if (e->interval < iter->interval) {
> +				p = iter;
> +				list_add(&e->list, iter->list.prev);
>  				break;
> +			}
>  		}
> -		list_add(&e->list, p->list.prev);
> +		if (!p)
> +			list_add(&e->list, gating_cfg->entries.prev);

This turns a pretty slick piece of code into something ugly :(
I'd rather you open coded the iteration here than make it more 
complex to satisfy "safe coding guidelines".

Also the list_add() could be converted to list_add_tail().