anycast: Some RCU conversions

- dev_get_by_flags() changed to dev_get_by_flags_rcu()

- ipv6_sock_ac_join() dont touch dev & idev refcounts
- ipv6_sock_ac_drop() dont touch dev & idev refcounts
- ipv6_sock_ac_close() dont touch dev & idev refcounts
- ipv6_dev_ac_dec() dount touch idev refcount
- ipv6_chk_acast_addr() dont touch idev refcount

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 49 insertions, 59 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 5156b806924c..c319f28d699d 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1271,8 +1271,8 @@ extern void		dev_add_pack(struct packet_type *pt);
 extern void             dev_remove_pack(struct packet_type *pt);
 extern void             __dev_remove_pack(struct packet_type *pt);
 
-extern struct net_device        *dev_get_by_flags(struct net *net, unsigned short flags,
-                                                  unsigned short mask);
+extern struct net_device        *dev_get_by_flags_rcu(struct net *net, unsigned short flags,
+                                                      unsigned short mask);
 extern struct net_device        *dev_get_by_name(struct net *net, const char *name);
 extern struct net_device        *dev_get_by_name_rcu(struct net *net, const char *name);
 extern struct net_device        *__dev_get_by_name(struct net *net, const char *name);
diff --git a/net/core/dev.c b/net/core/dev.c
index c8d127718ff1..6f330cee79a6 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -803,35 +803,31 @@ struct net_device *dev_getfirstbyhwtype(struct net *net, unsigned short type)
 EXPORT_SYMBOL(dev_getfirstbyhwtype);
 
 /**
- *      dev_get_by_flags - find any device with given flags
+ *      dev_get_by_flags_rcu - find any device with given flags
  *      @net: the applicable net namespace
  *      @if_flags: IFF_* values
  *      @mask: bitmask of bits in if_flags to check
  *
  *      Search for any interface with the given flags. Returns NULL if a device
- *      is not found or a pointer to the device. The device returned has
- *      had a reference added and the pointer is safe until the user calls
- *      dev_put to indicate they have finished with it.
+ *      is not found or a pointer to the device. Must be called inside
+ *      rcu_read_lock(), and result refcount is unchanged.
  */
 
-struct net_device *dev_get_by_flags(struct net *net, unsigned short if_flags,
+struct net_device *dev_get_by_flags_rcu(struct net *net, unsigned short if_flags,
                                     unsigned short mask)
 {
         struct net_device *dev, *ret;
 
         ret = NULL;
-        rcu_read_lock();
         for_each_netdev_rcu(net, dev) {
                 if (((dev->flags ^ if_flags) & mask) == 0) {
-                        dev_hold(dev);
                         ret = dev;
                         break;
                 }
         }
-        rcu_read_unlock();
         return ret;
 }
-EXPORT_SYMBOL(dev_get_by_flags);
+EXPORT_SYMBOL(dev_get_by_flags_rcu);
 
 /**
  *      dev_valid_name - check if name is okay for network device
diff --git a/net/ipv6/anycast.c b/net/ipv6/anycast.c
index b5b07054508a..f058fbd808c8 100644
--- a/net/ipv6/anycast.c
+++ b/net/ipv6/anycast.c
@@ -77,41 +77,40 @@ int ipv6_sock_ac_join(struct sock *sk, int ifindex, struct in6_addr *addr)
         pac->acl_next = NULL;
         ipv6_addr_copy(&pac->acl_addr, addr);
 
+        rcu_read_lock();
         if (ifindex == 0) {
                 struct rt6_info *rt;
 
                 rt = rt6_lookup(net, addr, NULL, 0, 0);
                 if (rt) {
                         dev = rt->rt6i_dev;
-                        dev_hold(dev);
                         dst_release(&rt->u.dst);
                 } else if (ishost) {
                         err = -EADDRNOTAVAIL;
-                        goto out_free_pac;
+                        goto error;
                 } else {
                         /* router, no matching interface: just pick one */
-
-                        dev = dev_get_by_flags(net, IFF_UP, IFF_UP|IFF_LOOPBACK);
+                        dev = dev_get_by_flags_rcu(net, IFF_UP,
+                                                   IFF_UP | IFF_LOOPBACK);
                 }
         } else
-                dev = dev_get_by_index(net, ifindex);
+                dev = dev_get_by_index_rcu(net, ifindex);
 
         if (dev == NULL) {
                 err = -ENODEV;
-                goto out_free_pac;
+                goto error;
         }
 
-        idev = in6_dev_get(dev);
+        idev = __in6_dev_get(dev);
         if (!idev) {
                 if (ifindex)
                         err = -ENODEV;
                 else
                         err = -EADDRNOTAVAIL;
-                goto out_dev_put;
+                goto error;
         }
         /* reset ishost, now that we have a specific device */
         ishost = !idev->cnf.forwarding;
-        in6_dev_put(idev);
 
         pac->acl_ifindex = dev->ifindex;
 
@@ -124,26 +123,22 @@ int ipv6_sock_ac_join(struct sock *sk, int ifindex, struct in6_addr *addr)
                 if (ishost)
                         err = -EADDRNOTAVAIL;
                 if (err)
-                        goto out_dev_put;
+                        goto error;
         }
 
         err = ipv6_dev_ac_inc(dev, addr);
-        if (err)
-                goto out_dev_put;
-
-        write_lock_bh(&ipv6_sk_ac_lock);
-        pac->acl_next = np->ipv6_ac_list;
-        np->ipv6_ac_list = pac;
-        write_unlock_bh(&ipv6_sk_ac_lock);
-
-        dev_put(dev);
-
-        return 0;
+        if (!err) {
+                write_lock_bh(&ipv6_sk_ac_lock);
+                pac->acl_next = np->ipv6_ac_list;
+                np->ipv6_ac_list = pac;
+                write_unlock_bh(&ipv6_sk_ac_lock);
+                pac = NULL;
+        }
 
-out_dev_put:
-        dev_put(dev);
-out_free_pac:
-        sock_kfree_s(sk, pac, sizeof(*pac));
+error:
+        rcu_read_unlock();
+        if (pac)
+                sock_kfree_s(sk, pac, sizeof(*pac));
         return err;
 }
 
@@ -176,11 +171,12 @@ int ipv6_sock_ac_drop(struct sock *sk, int ifindex, struct in6_addr *addr)
 
         write_unlock_bh(&ipv6_sk_ac_lock);
 
-        dev = dev_get_by_index(net, pac->acl_ifindex);
-        if (dev) {
+        rcu_read_lock();
+        dev = dev_get_by_index_rcu(net, pac->acl_ifindex);
+        if (dev)
                 ipv6_dev_ac_dec(dev, &pac->acl_addr);
-                dev_put(dev);
-        }
+        rcu_read_unlock();
+
         sock_kfree_s(sk, pac, sizeof(*pac));
         return 0;
 }
@@ -199,13 +195,12 @@ void ipv6_sock_ac_close(struct sock *sk)
         write_unlock_bh(&ipv6_sk_ac_lock);
 
         prev_index = 0;
+        rcu_read_lock();
         while (pac) {
                 struct ipv6_ac_socklist *next = pac->acl_next;
 
                 if (pac->acl_ifindex != prev_index) {
-                        if (dev)
-                                dev_put(dev);
-                        dev = dev_get_by_index(net, pac->acl_ifindex);
+                        dev = dev_get_by_index_rcu(net, pac->acl_ifindex);
                         prev_index = pac->acl_ifindex;
                 }
                 if (dev)
@@ -213,8 +208,7 @@ void ipv6_sock_ac_close(struct sock *sk)
                 sock_kfree_s(sk, pac, sizeof(*pac));
                 pac = next;
         }
-        if (dev)
-                dev_put(dev);
+        rcu_read_unlock();
 }
 
 #if 0
@@ -363,33 +357,32 @@ int __ipv6_dev_ac_dec(struct inet6_dev *idev, struct in6_addr *addr)
         return 0;
 }
 
+/* called with rcu_read_lock() */
 static int ipv6_dev_ac_dec(struct net_device *dev, struct in6_addr *addr)
 {
-        int ret;
-        struct inet6_dev *idev = in6_dev_get(dev);
+        struct inet6_dev *idev = __in6_dev_get(dev);
+
         if (idev == NULL)
                 return -ENODEV;
-        ret = __ipv6_dev_ac_dec(idev, addr);
-        in6_dev_put(idev);
-        return ret;
+        return __ipv6_dev_ac_dec(idev, addr);
 }
 
 /*
  *      check if the interface has this anycast address
+ *      called with rcu_read_lock()
  */
 static int ipv6_chk_acast_dev(struct net_device *dev, struct in6_addr *addr)
 {
         struct inet6_dev *idev;
         struct ifacaddr6 *aca;
 
-        idev = in6_dev_get(dev);
+        idev = __in6_dev_get(dev);
         if (idev) {
                 read_lock_bh(&idev->lock);
                 for (aca = idev->ac_list; aca; aca = aca->aca_next)
                         if (ipv6_addr_equal(&aca->aca_addr, addr))
                                 break;
                 read_unlock_bh(&idev->lock);
-                in6_dev_put(idev);
                 return aca != NULL;
         }
         return 0;
@@ -403,14 +396,15 @@ int ipv6_chk_acast_addr(struct net *net, struct net_device *dev,
 {
         int found = 0;
 
-        if (dev)
-                return ipv6_chk_acast_dev(dev, addr);
         rcu_read_lock();
-        for_each_netdev_rcu(net, dev)
-                if (ipv6_chk_acast_dev(dev, addr)) {
-                        found = 1;
-                        break;
-                }
+        if (dev)
+                found = ipv6_chk_acast_dev(dev, addr);
+        else
+                for_each_netdev_rcu(net, dev)
+                        if (ipv6_chk_acast_dev(dev, addr)) {
+                                found = 1;
+                                break;
+                        }
         rcu_read_unlock();
         return found;
 }