unimore/kernel-hacking-2024-linux-steffo
unimore/kernel-hacking-2024-linux-steffo
1
Fork 0
Code Pull requests 5 Wiki Activity

net: make net->dev_unreg_count atomic

Browse source 
Having to acquire rtnl from netdev_run_todo() for every dismantled
device is not desirable when/if rtnl is under stress.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2022-02-09 18:59:32 -08:00 committed by David S. Miller
parent ca2d5f1ff0
commit ede6c39c4f
3 changed files with 6 additions and 9 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
include/net/net_namespace.h
View file

@ -63,7 +63,7 @@ struct net {
*/
spinlock_t rules_mod_lock;
unsigned int dev_unreg_count;
atomic_t dev_unreg_count;
unsigned int dev_base_seq; /* protected by rtnl_mutex */
int ifindex;

11
net/core/dev.c
View file

@ -9143,7 +9143,7 @@ DECLARE_WAIT_QUEUE_HEAD(netdev_unregistering_wq);
static void net_set_todo(struct net_device *dev)
{
list_add_tail(&dev->todo_list, &net_todo_list);
dev_net(dev)->dev_unreg_count++;
atomic_inc(&dev_net(dev)->dev_unreg_count);
}
static netdev_features_t netdev_sync_upper_features(struct net_device *lower,
@ -9965,11 +9965,8 @@ void netdev_run_todo(void)
if (dev->needs_free_netdev)
free_netdev(dev);
/* Report a network device has been unregistered */
rtnl_lock();
dev_net(dev)->dev_unreg_count--;
__rtnl_unlock();
wake_up(&netdev_unregistering_wq);
if (atomic_dec_and_test(&dev_net(dev)->dev_unreg_count))
wake_up(&netdev_unregistering_wq);
/* Free network device */
kobject_put(&dev->dev.kobj);
@ -10898,7 +10895,7 @@ static void __net_exit rtnl_lock_unregistering(struct list_head *net_list)
unregistering = false;
list_for_each_entry(net, net_list, exit_list) {
if (net->dev_unreg_count > 0) {
if (atomic_read(&net->dev_unreg_count) > 0) {
unregistering = true;
break;
}

2
net/core/rtnetlink.c
View file

@ -459,7 +459,7 @@ static void rtnl_lock_unregistering_all(void)
* setup_net() and cleanup_net() are not possible.
*/
for_each_net(net) {
if (net->dev_unreg_count > 0) {
if (atomic_read(&net->dev_unreg_count) > 0) {
unregistering = true;
break;
}