phonet: Convert phonet_device_list.lock to spinlock_t.

addr_doit() calls phonet_address_add() or phonet_address_del()
for RTM_NEWADDR or RTM_DELADDR, respectively.

Both functions only touch phonet_device_list(dev_net(dev)),
which is currently protected by RTNL and its dedicated mutex,
phonet_device_list.lock.

We will convert addr_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 6b2102b4ece38a7368be11c99a27442bfb4614a4..ac0331d83a810b9791f7f02bd06071589420351a 100644 (file)
--- a/include/net/phonet/pn_dev.h
+++ b/include/net/phonet/pn_dev.h
@@ -12,12 +12,13 @@
 
 #include <linux/list.h>
 #include <linux/mutex.h>
+#include <linux/spinlock.h>
 
 struct net;
 
 struct phonet_device_list {
        struct list_head list;
-       struct mutex lock;
+       spinlock_t lock;
 };
 
 struct phonet_device_list *phonet_device_list(struct net *net);

diff --git a/net/phonet/pn_dev.c b/net/phonet/pn_dev.c
index 2e7d850dc72668ed42e2e537c662902fea6e55e0..545279ef591082cd5996c02545f09f974377e86e 100644 (file)
--- a/net/phonet/pn_dev.c
+++ b/net/phonet/pn_dev.c
@@ -54,7 +54,7 @@ static struct phonet_device *__phonet_device_alloc(struct net_device *dev)
        pnd->netdev = dev;
        bitmap_zero(pnd->addrs, 64);
 
-       BUG_ON(!mutex_is_locked(&pndevs->lock));
+       lockdep_assert_held(&pndevs->lock);
        list_add_rcu(&pnd->list, &pndevs->list);
        return pnd;
 }
@@ -64,7 +64,8 @@ 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));
+       lockdep_assert_held(&pndevs->lock);
+
        list_for_each_entry(pnd, &pndevs->list, list) {
                if (pnd->netdev == dev)
                        return pnd;
@@ -91,11 +92,13 @@ static void phonet_device_destroy(struct net_device *dev)
 
        ASSERT_RTNL();
 
-       mutex_lock(&pndevs->lock);
+       spin_lock(&pndevs->lock);
+
        pnd = __phonet_get(dev);
        if (pnd)
                list_del_rcu(&pnd->list);
-       mutex_unlock(&pndevs->lock);
+
+       spin_unlock(&pndevs->lock);
 
        if (pnd) {
                struct net *net = dev_net(dev);
@@ -136,7 +139,8 @@ int phonet_address_add(struct net_device *dev, u8 addr)
        struct phonet_device *pnd;
        int err = 0;
 
-       mutex_lock(&pndevs->lock);
+       spin_lock(&pndevs->lock);
+
        /* Find or create Phonet-specific device data */
        pnd = __phonet_get(dev);
        if (pnd == NULL)
@@ -145,7 +149,9 @@ int phonet_address_add(struct net_device *dev, u8 addr)
                err = -ENOMEM;
        else if (test_and_set_bit(addr >> 2, pnd->addrs))
                err = -EEXIST;
-       mutex_unlock(&pndevs->lock);
+
+       spin_unlock(&pndevs->lock);
+
        return err;
 }
 
@@ -155,7 +161,8 @@ int phonet_address_del(struct net_device *dev, u8 addr)
        struct phonet_device *pnd;
        int err = 0;
 
-       mutex_lock(&pndevs->lock);
+       spin_lock(&pndevs->lock);
+
        pnd = __phonet_get(dev);
        if (!pnd || !test_and_clear_bit(addr >> 2, pnd->addrs)) {
                err = -EADDRNOTAVAIL;
@@ -164,7 +171,8 @@ int phonet_address_del(struct net_device *dev, u8 addr)
                list_del_rcu(&pnd->list);
        else
                pnd = NULL;
-       mutex_unlock(&pndevs->lock);
+
+       spin_unlock(&pndevs->lock);
 
        if (pnd)
                kfree_rcu(pnd, rcu);
@@ -313,7 +321,7 @@ static int __net_init phonet_init_net(struct net *net)
                return -ENOMEM;
 
        INIT_LIST_HEAD(&pnn->pndevs.list);
-       mutex_init(&pnn->pndevs.lock);
+       spin_lock_init(&pnn->pndevs.lock);
        mutex_init(&pnn->routes.lock);
        return 0;
 }