Re: [PATCH 3/4] can: Properly fill the netlink header when responding to RTM_GETROUTE

[Thomas Graf <tgraf@suug.ch>]

On Fri, Jul 06, 2012 at 10:39:05PM +0200, Oliver Hartkopp wrote:
> what about this approach which reduces the number of parameters and stack
> space when calling cgw_put_job() ??
> 
> 
> diff --git a/net/can/gw.c b/net/can/gw.c
> index b41acf2..b6b9e0a 100644
> --- a/net/can/gw.c
> +++ b/net/can/gw.c
> @@ -444,11 +444,15 @@ static int cgw_notifier(struct notifier_block *nb,
>  	return NOTIFY_DONE;
>  }
>  
> -static int cgw_put_job(struct sk_buff *skb, struct cgw_job *gwj)
> +static int cgw_put_job(struct sk_buff *skb, struct cgw_job *gwj,
> +		       struct netlink_callback *cb)
>  {
>  	struct cgw_frame_mod mb;
>  	struct rtcanmsg *rtcan;
> -	struct nlmsghdr *nlh = nlmsg_put(skb, 0, 0, 0, sizeof(*rtcan), 0);
> +	struct nlmsghdr *nlh;
> +
> +	nlh = nlmsg_put(skb, NETLINK_CB(cb->skb).pid, cb->nlh->nlmsg_seq,
> +			RTM_NEWROUTE, sizeof(*rtcan), NLM_F_MULTI);
>  	if (!nlh)
>  		return -EMSGSIZE;
>  
> @@ -571,7 +575,7 @@ static int cgw_dump_jobs(struct sk_buff *skb, struct netlink_callback *cb)
>  		if (idx < s_idx)
>  			goto cont;
>  
> -		if (cgw_put_job(skb, gwj) < 0)
> +		if (cgw_put_job(skb, gwj, cb) < 0)
>  			break;
>  cont:
>  		idx++;

The format I've chosen allows to implement a non-dump RTM_GETROUTE using
cgw_put_job() if needed and is in line with how such filling functions
are typically prototyped in other netlink protocol implementations.

~Thomas