Kernel/linux
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2025-01-04 04:04:19 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

rtnetlink: Remove __rtnl_link_unregister().

Browse Source 
rtnl_link_unregister() holds RTNL and calls __rtnl_link_unregister(),
where we call synchronize_srcu() to wait inflight RTM_NEWLINK requests
for per-netns RTNL.

We put synchronize_srcu() in __rtnl_link_unregister() due to ifb.ko
and dummy.ko.

However, rtnl_newlink() will acquire SRCU before RTNL later in this
series.  Then, lockdep will detect the deadlock:

   rtnl_link_unregister()       rtnl_newlink()
   ----                         ----
   lock(rtnl_mutex);
                                lock(&ops->srcu);
                                lock(rtnl_mutex);
   sync(&ops->srcu);

To avoid the problem, we must call synchronize_srcu() before RTNL in
rtnl_link_unregister().

As a preparation, let's remove __rtnl_link_unregister().

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20241108004823.29419-2-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Kuniyuki Iwashima 2024-11-07 16:48:14 -08:00 committed by Jakub Kicinski
parent 7a3bcd39ae
commit d5ec8d91f8
4 changed files with 20 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
drivers/net/dummy.c
View File

@ -166,6 +166,7 @@ static int __init dummy_init_one(void)
static int __init dummy_init_module(void)
{
bool need_unregister = false;
int i, err = 0;
down_write(&pernet_ops_rwsem);
@ -179,12 +180,15 @@ static int __init dummy_init_module(void)
cond_resched();
}
if (err < 0)
__rtnl_link_unregister(&dummy_link_ops);
need_unregister = true;
out:
rtnl_unlock();
up_write(&pernet_ops_rwsem);
if (need_unregister)
rtnl_link_unregister(&dummy_link_ops);
return err;
}

6
drivers/net/ifb.c
View File

@ -424,6 +424,7 @@ static int __init ifb_init_one(int index)
static int __init ifb_init_module(void)
{
bool need_unregister = false;
int i, err;
down_write(&pernet_ops_rwsem);
@ -437,12 +438,15 @@ static int __init ifb_init_module(void)
cond_resched();
}
if (err)
__rtnl_link_unregister(&ifb_link_ops);
need_unregister = true;
out:
rtnl_unlock();
up_write(&pernet_ops_rwsem);
if (need_unregister)
rtnl_link_unregister(&ifb_link_ops);
return err;
}

1
include/net/rtnetlink.h
View File

@ -165,7 +165,6 @@ struct rtnl_link_ops {
};
int __rtnl_link_register(struct rtnl_link_ops *ops);
void __rtnl_link_unregister(struct rtnl_link_ops *ops);
int rtnl_link_register(struct rtnl_link_ops *ops);
void rtnl_link_unregister(struct rtnl_link_ops *ops);

32
net/core/rtnetlink.c
View File

@ -568,27 +568,6 @@ static void __rtnl_kill_links(struct net *net, struct rtnl_link_ops *ops)
unregister_netdevice_many(&list_kill);
}
/**
* __rtnl_link_unregister - Unregister rtnl_link_ops from rtnetlink.
* @ops: struct rtnl_link_ops * to unregister
*
* The caller must hold the rtnl_mutex and guarantee net_namespace_list
* integrity (hold pernet_ops_rwsem for writing to close the race
* with setup_net() and cleanup_net()).
*/
void __rtnl_link_unregister(struct rtnl_link_ops *ops)
{
struct net *net;
list_del_rcu(&ops->list);
synchronize_srcu(&ops->srcu);
cleanup_srcu_struct(&ops->srcu);
for_each_net(net)
__rtnl_kill_links(net, ops);
}
EXPORT_SYMBOL_GPL(__rtnl_link_unregister);
/* Return with the rtnl_lock held when there are no network
* devices unregistering in any network namespace.
*/
@ -617,10 +596,19 @@ static void rtnl_lock_unregistering_all(void)
*/
void rtnl_link_unregister(struct rtnl_link_ops *ops)
{
struct net *net;
/* Close the race with setup_net() and cleanup_net() */
down_write(&pernet_ops_rwsem);
rtnl_lock_unregistering_all();
__rtnl_link_unregister(ops);
list_del_rcu(&ops->list);
synchronize_srcu(&ops->srcu);
cleanup_srcu_struct(&ops->srcu);
for_each_net(net)
__rtnl_kill_links(net, ops);
rtnl_unlock();
up_write(&pernet_ops_rwsem);
}