Phonet: convert devices list to RCU

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

2 files changed, 44 insertions, 25 deletions

diff --git a/net/phonet/pn_dev.c b/net/phonet/pn_dev.c
index d5ad7947d771..d87388c94b00 100644
--- a/net/phonet/pn_dev.c
+++ b/net/phonet/pn_dev.c
@@ -61,7 +61,8 @@ static struct phonet_device *__phonet_device_alloc(struct net_device *dev)
         pnd->netdev = dev;
         bitmap_zero(pnd->addrs, 64);
 
-        list_add(&pnd->list, &pndevs->list);
+        BUG_ON(!mutex_is_locked(&pndevs->lock));
+        list_add_rcu(&pnd->list, &pndevs->list);
         return pnd;
 }
 
@@ -70,6 +71,7 @@ static struct phonet_device *__phonet_get(struct net_device *dev)
         struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
         struct phonet_device *pnd;
 
+        BUG_ON(!mutex_is_locked(&pndevs->lock));
         list_for_each_entry(pnd, &pndevs->list, list) {
                 if (pnd->netdev == dev)
                         return pnd;
@@ -77,6 +79,18 @@ static struct phonet_device *__phonet_get(struct net_device *dev)
         return NULL;
 }
 
+static struct phonet_device *__phonet_get_rcu(struct net_device *dev)
+{
+        struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
+        struct phonet_device *pnd;
+
+        list_for_each_entry_rcu(pnd, &pndevs->list, list) {
+                if (pnd->netdev == dev)
+                        return pnd;
+        }
+        return NULL;
+}
+
 static void phonet_device_destroy(struct net_device *dev)
 {
         struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
@@ -84,11 +98,11 @@ static void phonet_device_destroy(struct net_device *dev)
 
         ASSERT_RTNL();
 
-        spin_lock_bh(&pndevs->lock);
+        mutex_lock(&pndevs->lock);
         pnd = __phonet_get(dev);
         if (pnd)
-                list_del(&pnd->list);
-        spin_unlock_bh(&pndevs->lock);
+                list_del_rcu(&pnd->list);
+        mutex_unlock(&pndevs->lock);
 
         if (pnd) {
                 u8 addr;
@@ -106,8 +120,8 @@ struct net_device *phonet_device_get(struct net *net)
         struct phonet_device *pnd;
         struct net_device *dev = NULL;
 
-        spin_lock_bh(&pndevs->lock);
-        list_for_each_entry(pnd, &pndevs->list, list) {
+        rcu_read_lock();
+        list_for_each_entry_rcu(pnd, &pndevs->list, list) {
                 dev = pnd->netdev;
                 BUG_ON(!dev);
 
@@ -118,7 +132,7 @@ struct net_device *phonet_device_get(struct net *net)
         }
         if (dev)
                 dev_hold(dev);
-        spin_unlock_bh(&pndevs->lock);
+        rcu_read_unlock();
         return dev;
 }
 
@@ -128,7 +142,7 @@ int phonet_address_add(struct net_device *dev, u8 addr)
         struct phonet_device *pnd;
         int err = 0;
 
-        spin_lock_bh(&pndevs->lock);
+        mutex_lock(&pndevs->lock);
         /* Find or create Phonet-specific device data */
         pnd = __phonet_get(dev);
         if (pnd == NULL)
@@ -137,7 +151,7 @@ int phonet_address_add(struct net_device *dev, u8 addr)
                 err = -ENOMEM;
         else if (test_and_set_bit(addr >> 2, pnd->addrs))
                 err = -EEXIST;
-        spin_unlock_bh(&pndevs->lock);
+        mutex_unlock(&pndevs->lock);
         return err;
 }
 
@@ -147,27 +161,32 @@ int phonet_address_del(struct net_device *dev, u8 addr)
         struct phonet_device *pnd;
         int err = 0;
 
-        spin_lock_bh(&pndevs->lock);
+        mutex_lock(&pndevs->lock);
         pnd = __phonet_get(dev);
-        if (!pnd || !test_and_clear_bit(addr >> 2, pnd->addrs))
+        if (!pnd || !test_and_clear_bit(addr >> 2, pnd->addrs)) {
                 err = -EADDRNOTAVAIL;
-        else if (bitmap_empty(pnd->addrs, 64)) {
-                list_del(&pnd->list);
+                pnd = NULL;
+        } else if (bitmap_empty(pnd->addrs, 64))
+                list_del_rcu(&pnd->list);
+        else
+                pnd = NULL;
+        mutex_unlock(&pndevs->lock);
+
+        if (pnd) {
+                synchronize_rcu();
                 kfree(pnd);
         }
-        spin_unlock_bh(&pndevs->lock);
         return err;
 }
 
 /* Gets a source address toward a destination, through a interface. */
 u8 phonet_address_get(struct net_device *dev, u8 daddr)
 {
-        struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
         struct phonet_device *pnd;
         u8 saddr;
 
-        spin_lock_bh(&pndevs->lock);
-        pnd = __phonet_get(dev);
+        rcu_read_lock();
+        pnd = __phonet_get_rcu(dev);
         if (pnd) {
                 BUG_ON(bitmap_empty(pnd->addrs, 64));
 
@@ -178,7 +197,7 @@ u8 phonet_address_get(struct net_device *dev, u8 daddr)
                         saddr = find_first_bit(pnd->addrs, 64) << 2;
         } else
                 saddr = PN_NO_ADDR;
-        spin_unlock_bh(&pndevs->lock);
+        rcu_read_unlock();
 
         if (saddr == PN_NO_ADDR) {
                 /* Fallback to another device */
@@ -200,8 +219,8 @@ int phonet_address_lookup(struct net *net, u8 addr)
         struct phonet_device *pnd;
         int err = -EADDRNOTAVAIL;
 
-        spin_lock_bh(&pndevs->lock);
-        list_for_each_entry(pnd, &pndevs->list, list) {
+        rcu_read_lock();
+        list_for_each_entry_rcu(pnd, &pndevs->list, list) {
                 /* Don't allow unregistering devices! */
                 if ((pnd->netdev->reg_state != NETREG_REGISTERED) ||
                                 ((pnd->netdev->flags & IFF_UP)) != IFF_UP)
@@ -213,7 +232,7 @@ int phonet_address_lookup(struct net *net, u8 addr)
                 }
         }
 found:
-        spin_unlock_bh(&pndevs->lock);
+        rcu_read_unlock();
         return err;
 }
 
@@ -304,7 +323,7 @@ static int phonet_init_net(struct net *net)
         }
 
         INIT_LIST_HEAD(&pnn->pndevs.list);
-        spin_lock_init(&pnn->pndevs.lock);
+        mutex_init(&pnn->pndevs.lock);
         mutex_init(&pnn->routes.lock);
         net_assign_generic(net, phonet_net_id, pnn);
         return 0;
diff --git a/net/phonet/pn_netlink.c b/net/phonet/pn_netlink.c
index 609e509b369b..2e6c7eb8e76a 100644
--- a/net/phonet/pn_netlink.c
+++ b/net/phonet/pn_netlink.c
@@ -131,8 +131,8 @@ static int getaddr_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
         int addr_idx = 0, addr_start_idx = cb->args[1];
 
         pndevs = phonet_device_list(sock_net(skb->sk));
-        spin_lock_bh(&pndevs->lock);
-        list_for_each_entry(pnd, &pndevs->list, list) {
+        rcu_read_lock();
+        list_for_each_entry_rcu(pnd, &pndevs->list, list) {
                 u8 addr;
 
                 if (dev_idx > dev_start_idx)
@@ -154,7 +154,7 @@ static int getaddr_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
         }
 
 out:
-        spin_unlock_bh(&pndevs->lock);
+        rcu_read_unlock();
         cb->args[0] = dev_idx;
         cb->args[1] = addr_idx;