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

[Oliver Hartkopp <socketcan@hartkopp.net>]

On 09.07.2012 11:43, Thomas Graf wrote:

> 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.
> 


Yes, i also checked that the format was commonly used, but i did not find any
use-case for cgw_put_job() besides the full dump ...

Btw. both approaches are fine to me then.

Many thanks,
Oliver