net: Convert atomic_t net::count to refcount_t

Since net could be obtained from RCU lists,
and there is a race with net destruction,
the patch converts net::count to refcount_t.

This provides sanity checks for the cases of
incrementing counter of already dead net,
when maybe_get_net() has to used instead
of get_net().

Drivers: allyesconfig and allmodconfig are OK.

Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 14 insertions, 14 deletions

diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 10f99dafd5ac..f8a84a2c2341 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -51,7 +51,7 @@ struct net {
         refcount_t              passive;        /* To decided when the network
                                                  * namespace should be freed.
                                                  */
-        atomic_t                count;          /* To decided when the network
+        refcount_t              count;          /* To decided when the network
                                                  *  namespace should be shut down.
                                                  */
         spinlock_t              rules_mod_lock;
@@ -195,7 +195,7 @@ void __put_net(struct net *net);
 
 static inline struct net *get_net(struct net *net)
 {
-        atomic_inc(&net->count);
+        refcount_inc(&net->count);
         return net;
 }
 
@@ -206,14 +206,14 @@ static inline struct net *maybe_get_net(struct net *net)
          * exists.  If the reference count is zero this
          * function fails and returns NULL.
          */
-        if (!atomic_inc_not_zero(&net->count))
+        if (!refcount_inc_not_zero(&net->count))
                 net = NULL;
         return net;
 }
 
 static inline void put_net(struct net *net)
 {
-        if (atomic_dec_and_test(&net->count))
+        if (refcount_dec_and_test(&net->count))
                 __put_net(net);
 }
 
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 799b75268291..7bf8b85ade16 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -961,7 +961,7 @@ net_rx_queue_update_kobjects(struct net_device *dev, int old_num, int new_num)
         while (--i >= new_num) {
                 struct kobject *kobj = &dev->_rx[i].kobj;
 
-                if (!atomic_read(&dev_net(dev)->count))
+                if (!refcount_read(&dev_net(dev)->count))
                         kobj->uevent_suppress = 1;
                 if (dev->sysfs_rx_queue_group)
                         sysfs_remove_group(kobj, dev->sysfs_rx_queue_group);
@@ -1367,7 +1367,7 @@ netdev_queue_update_kobjects(struct net_device *dev, int old_num, int new_num)
         while (--i >= new_num) {
                 struct netdev_queue *queue = dev->_tx + i;
 
-                if (!atomic_read(&dev_net(dev)->count))
+                if (!refcount_read(&dev_net(dev)->count))
                         queue->kobj.uevent_suppress = 1;
 #ifdef CONFIG_BQL
                 sysfs_remove_group(&queue->kobj, &dql_group);
@@ -1558,7 +1558,7 @@ void netdev_unregister_kobject(struct net_device *ndev)
 {
         struct device *dev = &ndev->dev;
 
-        if (!atomic_read(&dev_net(ndev)->count))
+        if (!refcount_read(&dev_net(ndev)->count))
                 dev_set_uevent_suppress(dev, 1);
 
         kobject_get(&dev->kobj);
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 60a71be75aea..2213d45fcafd 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -35,7 +35,7 @@ LIST_HEAD(net_namespace_list);
 EXPORT_SYMBOL_GPL(net_namespace_list);
 
 struct net init_net = {
-        .count          = ATOMIC_INIT(1),
+        .count          = REFCOUNT_INIT(1),
         .dev_base_head  = LIST_HEAD_INIT(init_net.dev_base_head),
 };
 EXPORT_SYMBOL(init_net);
@@ -224,10 +224,10 @@ int peernet2id_alloc(struct net *net, struct net *peer)
         bool alloc;
         int id;
 
-        if (atomic_read(&net->count) == 0)
+        if (refcount_read(&net->count) == 0)
                 return NETNSA_NSID_NOT_ASSIGNED;
         spin_lock_bh(&net->nsid_lock);
-        alloc = atomic_read(&peer->count) == 0 ? false : true;
+        alloc = refcount_read(&peer->count) == 0 ? false : true;
         id = __peernet2id_alloc(net, peer, &alloc);
         spin_unlock_bh(&net->nsid_lock);
         if (alloc && id >= 0)
@@ -284,7 +284,7 @@ static __net_init int setup_net(struct net *net, struct user_namespace *user_ns)
         int error = 0;
         LIST_HEAD(net_exit_list);
 
-        atomic_set(&net->count, 1);
+        refcount_set(&net->count, 1);
         refcount_set(&net->passive, 1);
         net->dev_base_seq = 1;
         net->user_ns = user_ns;
diff --git a/net/ipv4/inet_timewait_sock.c b/net/ipv4/inet_timewait_sock.c
index 277ff69a312d..c3ea4906d237 100644
--- a/net/ipv4/inet_timewait_sock.c
+++ b/net/ipv4/inet_timewait_sock.c
@@ -270,14 +270,14 @@ restart:
                                 continue;
                         tw = inet_twsk(sk);
                         if ((tw->tw_family != family) ||
-                                atomic_read(&twsk_net(tw)->count))
+                                refcount_read(&twsk_net(tw)->count))
                                 continue;
 
                         if (unlikely(!refcount_inc_not_zero(&tw->tw_refcnt)))
                                 continue;
 
                         if (unlikely((tw->tw_family != family) ||
-                                     atomic_read(&twsk_net(tw)->count))) {
+                                     refcount_read(&twsk_net(tw)->count))) {
                                 inet_twsk_put(tw);
                                 goto restart;
                         }
diff --git a/net/ipv4/tcp_metrics.c b/net/ipv4/tcp_metrics.c
index 759e6bc8327b..03b51cdcc731 100644
--- a/net/ipv4/tcp_metrics.c
+++ b/net/ipv4/tcp_metrics.c
@@ -892,7 +892,7 @@ static void tcp_metrics_flush_all(struct net *net)
                 pp = &hb->chain;
                 for (tm = deref_locked(*pp); tm; tm = deref_locked(*pp)) {
                         match = net ? net_eq(tm_net(tm), net) :
-                                !atomic_read(&tm_net(tm)->count);
+                                !refcount_read(&tm_net(tm)->count);
                         if (match) {
                                 *pp = tm->tcpm_next;
                                 kfree_rcu(tm, rcu_head);