Re: [B.A.T.M.A.N.] [PATCHv2 1/7] batman-adv: prevent multiple ARP replies sent by gateways if dat enabled

[Antonio Quartulli <a@unstable.cc>]

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Hi Andreas and thanks for your work on this topic :)

please find some comments inline

On Fri, Feb 26, 2016 at 02:17:46PM +0100, Andreas Pape wrote:

...

> +bool batadv_bla_handle_local_claim(struct batadv_priv *bat_priv,
> +				   u8 *addr, unsigned short vid)
> +{
> +	struct batadv_bla_claim search_claim;
> +	struct batadv_bla_claim *claim = NULL;
> +	struct batadv_hard_iface *primary_if = NULL;
> +	bool ret = true;
> +
> +	if (!atomic_read(&bat_priv->bridge_loop_avoidance))
> +		return ret;
> +
> +	primary_if = batadv_primary_if_get_selected(bat_priv);
> +	if (!primary_if)
> +		goto out;

do you really need this goto here ? I think you can just return ret.

This way you can avoid the blind initialization of claim and primary_if and you
can also remove the 'out' label at all.

> +
> +	/* First look if the mac address is claimed */
> +	ether_addr_copy(search_claim.addr, addr);
> +	search_claim.vid = vid;
> +
> +	claim = batadv_claim_hash_find(bat_priv, &search_claim);
> +
> +	/* If there is a claim and we are not owner of the claim,
> +	 * return false;

no need for the ';' here :)

> +	 */
> +	if (claim) {
> +		if (!batadv_compare_eth(claim->backbone_gw->orig,
> +					primary_if->net_dev->dev_addr))
> +			ret = false;
> +	} else {
> +		/* If there is no claim, claim the device */
> +		batadv_dbg(BATADV_DBG_BLA, bat_priv,
> +			   "Handle claim locally for currently not claimed mac %pM.\n",
> +			   search_claim.addr);
> +
> +		batadv_handle_claim(bat_priv, primary_if,
> +				    primary_if->net_dev->dev_addr, addr, vid);
> +	}
> +

...

> @@ -1000,6 +1001,20 @@ bool batadv_dat_snoop_outgoing_arp_request(struct batadv_priv *bat_priv,
>  			goto out;
>  		}
> 
> +		/* If BLA is enabled, only send ARP replies if we have claimed
> +		 * the destination for the ARP request or if no one else of
> +		 * the backbone gws belonging to our backbone has claimed the
> +		 * destination.
> +		 */
> +		if (!batadv_bla_handle_local_claim(bat_priv,
> +						   dat_entry->mac_addr, vid)) {

I like the approach you take to fix this issue, however I don't understand why
you want to "manually" claim a client.

If I recall correctly, a backbone node
will try to claim a client only if the latter tries to use such node to enter
the LAN.
In this situation the client may never use this backbone to enter the LAN (i.e. bad
metric towards this node) and therefore we are forcing a claim that is not
correct.

Simon, what do you think ?

Imho it is ok to *not* reply to the ARP request is the client is not claimed,
but I don't understand why claiming it now.


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Are you sure this footer does not conflict with the GPL ? Not sure how important
this is, but I'd rather not send it along with patches.
However, if you use git-send-email this footer should not appear at all.


Cheers,


-- 
Antonio Quartulli

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