phonet: Convert phonet_routes.lock to spinlock_t.

route_doit() calls phonet_route_add() or phonet_route_del()
for RTM_NEWROUTE or RTM_DELROUTE, respectively.

Both functions only touch phonet_pernet(dev_net(dev))->routes,
which is currently protected by RTNL and its dedicated mutex,
phonet_routes.lock.

We will convert route_doit() to RCU and cannot use mutex inside RCU.

Let's convert the mutex to spinlock_t.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/include/net/phonet/pn_dev.h b/include/net/phonet/pn_dev.h
index 021e524fd20a873ee1766dddced1701963e69361..37a3e83531c63471ac59a34ac7dfeb70afea783c 100644 (file)
--- a/include/net/phonet/pn_dev.h
+++ b/include/net/phonet/pn_dev.h
@@ -11,7 +11,6 @@
 #define PN_DEV_H
 
 #include <linux/list.h>
-#include <linux/mutex.h>
 #include <linux/spinlock.h>
 
 struct net;

diff --git a/net/phonet/pn_dev.c b/net/phonet/pn_dev.c
index 6ded0d347b9fd4fef0082a12871cce4d6d1e736d..19234d664c4fb537eba0267266efbb226cf103c3 100644 (file)
--- a/net/phonet/pn_dev.c
+++ b/net/phonet/pn_dev.c
@@ -22,7 +22,7 @@
 #include <net/phonet/pn_dev.h>
 
 struct phonet_routes {
-       struct mutex            lock;
+       spinlock_t              lock;
        struct net_device __rcu *table[64];
 };
 
@@ -273,13 +273,15 @@ static void phonet_route_autodel(struct net_device *dev)
 
        /* Remove left-over Phonet routes */
        bitmap_zero(deleted, 64);
-       mutex_lock(&pnn->routes.lock);
-       for (i = 0; i < 64; i++)
+
+       spin_lock(&pnn->routes.lock);
+       for (i = 0; i < 64; i++) {
                if (rcu_access_pointer(pnn->routes.table[i]) == dev) {
                        RCU_INIT_POINTER(pnn->routes.table[i], NULL);
                        set_bit(i, deleted);
                }
-       mutex_unlock(&pnn->routes.lock);
+       }
+       spin_unlock(&pnn->routes.lock);
 
        if (bitmap_empty(deleted, 64))
                return; /* short-circuit RCU */
@@ -326,7 +328,7 @@ static int __net_init phonet_init_net(struct net *net)
 
        INIT_LIST_HEAD(&pnn->pndevs.list);
        spin_lock_init(&pnn->pndevs.lock);
-       mutex_init(&pnn->routes.lock);
+       spin_lock_init(&pnn->routes.lock);
        return 0;
 }
 
@@ -376,13 +378,15 @@ int phonet_route_add(struct net_device *dev, u8 daddr)
        int err = -EEXIST;
 
        daddr = daddr >> 2;
-       mutex_lock(&routes->lock);
+
+       spin_lock(&routes->lock);
        if (routes->table[daddr] == NULL) {
                rcu_assign_pointer(routes->table[daddr], dev);
                dev_hold(dev);
                err = 0;
        }
-       mutex_unlock(&routes->lock);
+       spin_unlock(&routes->lock);
+
        return err;
 }
 
@@ -392,12 +396,13 @@ int phonet_route_del(struct net_device *dev, u8 daddr)
        struct phonet_routes *routes = &pnn->routes;
 
        daddr = daddr >> 2;
-       mutex_lock(&routes->lock);
+
+       spin_lock(&routes->lock);
        if (rcu_access_pointer(routes->table[daddr]) == dev)
                RCU_INIT_POINTER(routes->table[daddr], NULL);
        else
                dev = NULL;
-       mutex_unlock(&routes->lock);
+       spin_unlock(&routes->lock);
 
        if (!dev)
                return -ENOENT;