decnet: RCU conversion and get rid of dev_base_lock

While tracking dev_base_lock users, I found decnet used it in dnet_select_source(), but for a wrong purpose: Writers only hold RTNL, not dev_base_lock, so readers must use RCU if they cannot use RTNL. Adds an rcu_head in struct dn_ifaddr and handle proper RCU management. Adds __rcu annotation in dn_route as well. Signed-off-by: Eric Dumazet <[email protected]> Acked-by: Steven Whitehouse <[email protected]> Signed-off-by: David S. Miller <[email protected]>
gunnarahlberg · Nov 8, 2010 · fc766e4 · fc766e4
1 parent e4a7b93
commit fc766e4
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Showing 8 changed files with 127 additions and 88 deletions.
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
@@ -951,7 +951,7 @@ struct net_device {
 #endif
 	void 			*atalk_ptr;	/* AppleTalk link 	*/
 	struct in_device __rcu	*ip_ptr;	/* IPv4 specific data	*/
-	void                    *dn_ptr;        /* DECnet specific data */
+	struct dn_dev __rcu     *dn_ptr;        /* DECnet specific data */
 	struct inet6_dev __rcu	*ip6_ptr;       /* IPv6 specific data */
 	void			*ec_ptr;	/* Econet specific data	*/
 	void			*ax25_ptr;	/* AX.25 specific data */

diff --git a/include/net/dn_dev.h b/include/net/dn_dev.h
@@ -5,13 +5,14 @@
 struct dn_dev;
 
 struct dn_ifaddr {
-	struct dn_ifaddr *ifa_next;
+	struct dn_ifaddr __rcu *ifa_next;
 	struct dn_dev    *ifa_dev;
 	__le16            ifa_local;
 	__le16            ifa_address;
 	__u8              ifa_flags;
 	__u8              ifa_scope;
 	char              ifa_label[IFNAMSIZ];
+	struct rcu_head   rcu;
 };
 
 #define DN_DEV_S_RU  0 /* Run - working normally   */
@@ -83,7 +84,7 @@ struct dn_dev_parms {
 
 
 struct dn_dev {
-	struct dn_ifaddr *ifa_list;
+	struct dn_ifaddr __rcu *ifa_list;
 	struct net_device *dev;
 	struct dn_dev_parms parms;
 	char use_long;
@@ -171,19 +172,27 @@ extern int unregister_dnaddr_notifier(struct notifier_block *nb);
 
 static inline int dn_dev_islocal(struct net_device *dev, __le16 addr)
 {
-	struct dn_dev *dn_db = dev->dn_ptr;
+	struct dn_dev *dn_db;
 	struct dn_ifaddr *ifa;
+	int res = 0;
 
+	rcu_read_lock();
+	dn_db = rcu_dereference(dev->dn_ptr);
 	if (dn_db == NULL) {
 		printk(KERN_DEBUG "dn_dev_islocal: Called for non DECnet device\n");
-		return 0;
+		goto out;
 	}
 
-	for(ifa = dn_db->ifa_list; ifa; ifa = ifa->ifa_next)
-		if ((addr ^ ifa->ifa_local) == 0)
-			return 1;
-
-	return 0;
+	for (ifa = rcu_dereference(dn_db->ifa_list);
+	     ifa != NULL;
+	     ifa = rcu_dereference(ifa->ifa_next))
+		if ((addr ^ ifa->ifa_local) == 0) {
+			res = 1;
+			break;
+		}
+out:
+	rcu_read_unlock();
+	return res;
 }
 
 #endif /* _NET_DN_DEV_H */
diff --git a/include/net/dst.h b/include/net/dst.h
@@ -94,10 +94,10 @@ struct dst_entry {
 	int			__use;
 	unsigned long		lastuse;
 	union {
-		struct dst_entry *next;
-		struct rtable __rcu *rt_next;
-		struct rt6_info   *rt6_next;
-		struct dn_route  *dn_next;
+		struct dst_entry	*next;
+		struct rtable __rcu	*rt_next;
+		struct rt6_info		*rt6_next;
+		struct dn_route __rcu	*dn_next;
 	};
 };
 

diff --git a/net/decnet/af_decnet.c b/net/decnet/af_decnet.c
@@ -1848,7 +1848,7 @@ unsigned dn_mss_from_pmtu(struct net_device *dev, int mtu)
 {
 	unsigned mss = 230 - DN_MAX_NSP_DATA_HEADER;
 	if (dev) {
-		struct dn_dev *dn_db = dev->dn_ptr;
+		struct dn_dev *dn_db = rcu_dereference_raw(dev->dn_ptr);
 		mtu -= LL_RESERVED_SPACE(dev);
 		if (dn_db->use_long)
 			mtu -= 21;