inet: RCU changes in inetdev_by_index()

Convert inetdev_by_index() to not increment in_dev refcount. Callers hold RCU or RTNL, and should not decrement in_dev refcount. Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>

inet: RCU changes in inetdev_by_index()
Convert inetdev_by_index() to not increment in_dev refcount. Callers hold RCU or RTNL, and should not decrement in_dev refcount. Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Eric Dumazet · David S. Miller
1 parent 9e917dca74
Showing 4 changed files with 16 additions and 22 deletions Side-by-side Diff
net/ipv4/devinet.c
net/ipv4/fib_semantics.c
net/ipv4/igmp.c
net/ipv4/ip_gre.c
@@ -403,6 +403,9 @@
 	return inet_insert_ifa(ifa);
 }
  
+/* Caller must hold RCU or RTNL :
+ * We dont take a reference on found in_device
+ */
 struct in_device *inetdev_by_index(struct net *net, int ifindex)
 {
 	struct net_device *dev;
@@ -411,7 +414,7 @@
 	rcu_read_lock();
 	dev = dev_get_by_index_rcu(net, ifindex);
 	if (dev)
-		in_dev = in_dev_get(dev);
+		in_dev = rcu_dereference_rtnl(dev->ip_ptr);
 	rcu_read_unlock();
 	return in_dev;
 }
@@ -452,8 +455,6 @@
 		err = -ENODEV;
 		goto errout;
 	}
-
-	__in_dev_put(in_dev);
  
 	for (ifap = &in_dev->ifa_list; (ifa = *ifap) != NULL;
 	     ifap = &ifa->ifa_next) {
@@ -590,32 +590,29 @@
 		if (!dev)
 			goto out;
 		dev_hold(dev);
-		err = -ENETDOWN;
-		if (!(dev->flags & IFF_UP))
-			goto out;
-		err = 0;
-out:
-		rcu_read_unlock();
-		return err;
+		err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
 	} else {
 		struct in_device *in_dev;
  
 		if (nh->nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK))
 			return -EINVAL;
  
+		rcu_read_lock();
+		err = -ENODEV;
 		in_dev = inetdev_by_index(net, nh->nh_oif);
 		if (in_dev == NULL)
-			return -ENODEV;
-		if (!(in_dev->dev->flags & IFF_UP)) {
-			in_dev_put(in_dev);
-			return -ENETDOWN;
-		}
+			goto out;
+		err = -ENETDOWN;
+		if (!(in_dev->dev->flags & IFF_UP))
+			goto out;
 		nh->nh_dev = in_dev->dev;
 		dev_hold(nh->nh_dev);
 		nh->nh_scope = RT_SCOPE_HOST;
-		in_dev_put(in_dev);
+		err = 0;
 	}
-	return 0;
+out:
+	rcu_read_unlock();
+	return err;
 }
  
 static inline unsigned int fib_laddr_hashfn(__be32 val)
@@ -1429,8 +1429,6 @@
  
 	if (imr->imr_ifindex) {
 		idev = inetdev_by_index(net, imr->imr_ifindex);
-		if (idev)
-			__in_dev_put(idev);
 		return idev;
 	}
 	if (imr->imr_address.s_addr) {
@@ -1245,10 +1245,8 @@
 	if (ipv4_is_multicast(t->parms.iph.daddr) && t->mlink) {
 		struct in_device *in_dev;
 		in_dev = inetdev_by_index(dev_net(dev), t->mlink);
-		if (in_dev) {
+		if (in_dev)
 			ip_mc_dec_group(in_dev, t->parms.iph.daddr);
-			in_dev_put(in_dev);
-		}
 	}
 	return 0;
 }
...	...	@@ -403,6 +403,9 @@
403	403	return inet_insert_ifa(ifa);
404	404	}
405	405
	406	+/* Caller must hold RCU or RTNL :
	407	+ * We dont take a reference on found in_device
	408	+ */
406	409	struct in_device inetdev_by_index(struct net net, int ifindex)
407	410	{
408	411	struct net_device *dev;
...	...	@@ -411,7 +414,7 @@
411	414	rcu_read_lock();
412	415	dev = dev_get_by_index_rcu(net, ifindex);
413	416	if (dev)
414		- in_dev = in_dev_get(dev);
	417	+ in_dev = rcu_dereference_rtnl(dev->ip_ptr);
415	418	rcu_read_unlock();
416	419	return in_dev;
417	420	}
...	...	@@ -452,8 +455,6 @@
452	455	err = -ENODEV;
453	456	goto errout;
454	457	}
455		-
456		- __in_dev_put(in_dev);
457	458
458	459	for (ifap = &in_dev->ifa_list; (ifa = *ifap) != NULL;
459	460	ifap = &ifa->ifa_next) {
...	...	@@ -590,32 +590,29 @@
590	590	if (!dev)
591	591	goto out;
592	592	dev_hold(dev);
593		- err = -ENETDOWN;
594		- if (!(dev->flags & IFF_UP))
595		- goto out;
596		- err = 0;
597		-out:
598		- rcu_read_unlock();
599		- return err;
	593	+ err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
600	594	} else {
601	595	struct in_device *in_dev;
602	596
603	597	if (nh->nh_flags & (RTNH_F_PERVASIVE \| RTNH_F_ONLINK))
604	598	return -EINVAL;
605	599
	600	+ rcu_read_lock();
	601	+ err = -ENODEV;
606	602	in_dev = inetdev_by_index(net, nh->nh_oif);
607	603	if (in_dev == NULL)
608		- return -ENODEV;
609		- if (!(in_dev->dev->flags & IFF_UP)) {
610		- in_dev_put(in_dev);
611		- return -ENETDOWN;
612		- }
	604	+ goto out;
	605	+ err = -ENETDOWN;
	606	+ if (!(in_dev->dev->flags & IFF_UP))
	607	+ goto out;
613	608	nh->nh_dev = in_dev->dev;
614	609	dev_hold(nh->nh_dev);
615	610	nh->nh_scope = RT_SCOPE_HOST;
616		- in_dev_put(in_dev);
	611	+ err = 0;
617	612	}
618		- return 0;
	613	+out:
	614	+ rcu_read_unlock();
	615	+ return err;
619	616	}
620	617
621	618	static inline unsigned int fib_laddr_hashfn(__be32 val)
...	...	@@ -1429,8 +1429,6 @@
1429	1429
1430	1430	if (imr->imr_ifindex) {
1431	1431	idev = inetdev_by_index(net, imr->imr_ifindex);
1432		- if (idev)
1433		- __in_dev_put(idev);
1434	1432	return idev;
1435	1433	}
1436	1434	if (imr->imr_address.s_addr) {
...	...	@@ -1245,10 +1245,8 @@
1245	1245	if (ipv4_is_multicast(t->parms.iph.daddr) && t->mlink) {
1246	1246	struct in_device *in_dev;
1247	1247	in_dev = inetdev_by_index(dev_net(dev), t->mlink);
1248		- if (in_dev) {
	1248	+ if (in_dev)
1249	1249	ip_mc_dec_group(in_dev, t->parms.iph.daddr);
1250		- in_dev_put(in_dev);
1251		- }
1252	1250	}
1253	1251	return 0;
1254	1252	}