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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>
This commit is contained in:
Kirill Tkhai 2018-01-12 18:28:31 +03:00 committed by David S. Miller
parent 594831a8ab
commit 273c28bc57
5 changed files with 14 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
include/net/net_namespace.h
View File

@ -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);
}

6
net/core/net-sysfs.c
View File

@ -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);

8
net/core/net_namespace.c
View File

@ -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;

4
net/ipv4/inet_timewait_sock.c
View File

@ -270,14 +270,14 @@ void inet_twsk_purge(struct inet_hashinfo *hashinfo, int family)
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;
}

2
net/ipv4/tcp_metrics.c
View File

@ -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);