[PATCH] net: igmp: use IS_ENABLED(CONFIG_IP_MULTICAST) instead of ifdef

On Tuesday 16 February 2016 18:10:52 Nikolay Borisov wrote:

On 02/16/2016 05:59 PM, Arnd Bergmann wrote:

quoted

@@ -1821,17 +1807,15 @@ static int ip_mc_del_src(struct in_device *in_dev, __be32 *pmca, int sfmode,
 		if (!err && rv < 0)
 			err = rv;
 	}
-	if (pmc->sfmode == MCAST_EXCLUDE &&
+	if (IS_ENABLED(CONFIG_IP_MULTICAST) &&
+	    pmc->sfmode == MCAST_EXCLUDE &&
 	    pmc->sfcount[MCAST_EXCLUDE] == 0 &&
 	    pmc->sfcount[MCAST_INCLUDE]) {
-#ifdef CONFIG_IP_MULTICAST
 		struct ip_sf_list *psf;
 		struct net *net = dev_net(in_dev->dev);
-#endif
 
 		/* filter mode change */
 		pmc->sfmode = MCAST_INCLUDE;

The above line was always executed, whereas now it wouldn't execute
unless IS_ENABLED passes.

This was not intentional, I've sent a v2 patch to fix it up now, and
tried to simplify it a little further, making the logic the
same for  ip_mc_del_src and ip_mc_add_src.

quoted

 /*
  * Add multicast source filter list to the interface list

@@ -1977,9 +1961,7 @@ static int ip_mc_add_src(struct in_device *in_dev, __be32 *pmca, int sfmode,
 	spin_lock_bh(&pmc->lock);
 	rcu_read_unlock();
 
-#ifdef CONFIG_IP_MULTICAST
 	sf_markstate(pmc);
-#endif

This would be executed unconditionally, which is contrary to the
original intention. Dunno if it makes a difference though.

This was intentional, I have changed sf_markstate() to do nothing when
IP_MULTICAST is disabled. However, there was another caller where
I should have done the same thing rather than adding an if().

Reviewed-by: Nikolay Borisov <redacted>

Thanks!

	Arnd