Phonet: convert routing table to RCU

Signed-off-by: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 34 insertions, 25 deletions

diff --git a/net/phonet/pn_dev.c b/net/phonet/pn_dev.c
index 6d64fda1afc9..3287f8f0b5cc 100644
--- a/net/phonet/pn_dev.c
+++ b/net/phonet/pn_dev.c
@@ -34,7 +34,7 @@
 #include <net/phonet/pn_dev.h>
 
 struct phonet_routes {
-        spinlock_t              lock;
+        struct mutex            lock;
         struct net_device       *table[64];
 };
 
@@ -248,17 +248,22 @@ static void phonet_route_autodel(struct net_device *dev)
 
         /* Remove left-over Phonet routes */
         bitmap_zero(deleted, 64);
-        spin_lock_bh(&pnn->routes.lock);
+        mutex_lock(&pnn->routes.lock);
         for (i = 0; i < 64; i++)
                 if (dev == pnn->routes.table[i]) {
+                        rcu_assign_pointer(pnn->routes.table[i], NULL);
                         set_bit(i, deleted);
-                        pnn->routes.table[i] = NULL;
-                        dev_put(dev);
                 }
-        spin_unlock_bh(&pnn->routes.lock);
+        mutex_unlock(&pnn->routes.lock);
+
+        if (bitmap_empty(deleted, 64))
+                return; /* short-circuit RCU */
+        synchronize_rcu();
         for (i = find_first_bit(deleted, 64); i < 64;
-                        i = find_next_bit(deleted, 64, i + 1))
+                        i = find_next_bit(deleted, 64, i + 1)) {
                 rtm_phonet_notify(RTM_DELROUTE, dev, i);
+                dev_put(dev);
+        }
 }
 
 /* notify Phonet of device events */
@@ -300,7 +305,7 @@ static int phonet_init_net(struct net *net)
 
         INIT_LIST_HEAD(&pnn->pndevs.list);
         spin_lock_init(&pnn->pndevs.lock);
-        spin_lock_init(&pnn->routes.lock);
+        mutex_init(&pnn->routes.lock);
         net_assign_generic(net, phonet_net_id, pnn);
         return 0;
 }
@@ -361,13 +366,13 @@ int phonet_route_add(struct net_device *dev, u8 daddr)
         int err = -EEXIST;
 
         daddr = daddr >> 2;
-        spin_lock_bh(&routes->lock);
+        mutex_lock(&routes->lock);
         if (routes->table[daddr] == NULL) {
-                routes->table[daddr] = dev;
+                rcu_assign_pointer(routes->table[daddr], dev);
                 dev_hold(dev);
                 err = 0;
         }
-        spin_unlock_bh(&routes->lock);
+        mutex_unlock(&routes->lock);
         return err;
 }
 
@@ -375,17 +380,20 @@ int phonet_route_del(struct net_device *dev, u8 daddr)
 {
         struct phonet_net *pnn = net_generic(dev_net(dev), phonet_net_id);
         struct phonet_routes *routes = &pnn->routes;
-        int err = -ENOENT;
 
         daddr = daddr >> 2;
-        spin_lock_bh(&routes->lock);
-        if (dev == routes->table[daddr]) {
-                routes->table[daddr] = NULL;
-                dev_put(dev);
-                err = 0;
-        }
-        spin_unlock_bh(&routes->lock);
-        return err;
+        mutex_lock(&routes->lock);
+        if (dev == routes->table[daddr])
+                rcu_assign_pointer(routes->table[daddr], NULL);
+        else
+                dev = NULL;
+        mutex_unlock(&routes->lock);
+
+        if (!dev)
+                return -ENOENT;
+        synchronize_rcu();
+        dev_put(dev);
+        return 0;
 }
 
 struct net_device *phonet_route_get(struct net *net, u8 daddr)
@@ -397,9 +405,9 @@ struct net_device *phonet_route_get(struct net *net, u8 daddr)
         ASSERT_RTNL(); /* no need to hold the device */
 
         daddr >>= 2;
-        spin_lock_bh(&routes->lock);
-        dev = routes->table[daddr];
-        spin_unlock_bh(&routes->lock);
+        rcu_read_lock();
+        dev = rcu_dereference(routes->table[daddr]);
+        rcu_read_unlock();
         return dev;
 }
 
@@ -409,11 +417,12 @@ struct net_device *phonet_route_output(struct net *net, u8 daddr)
         struct phonet_routes *routes = &pnn->routes;
         struct net_device *dev;
 
-        spin_lock_bh(&routes->lock);
-        dev = routes->table[daddr >> 2];
+        daddr >>= 2;
+        rcu_read_lock();
+        dev = rcu_dereference(routes->table[daddr]);
         if (dev)
                 dev_hold(dev);
-        spin_unlock_bh(&routes->lock);
+        rcu_read_unlock();
 
         if (!dev)
                 dev = phonet_device_get(net); /* Default route */