Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
net: let lockdep compare instance locks
AFAIU always returning -1 from lockdep's compare function
basically disables checking of dependencies between given
locks. Try to be a little more precise about what guarantees
that instance locks won't deadlock.
Right now we only nest them under protection of rtnl_lock.
Mostly in unregister_netdevice_many() and dev_close_many().
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250517200810.466531-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
+7
-8
+7
-8
include/net/netdev_lock.h
+7
-8
include/net/netdev_lock.h
···
99
99
static inline int netdev_lock_cmp_fn(const struct lockdep_map *a,
100
100
const struct lockdep_map *b)
101
101
{
102
-
/* Only lower devices currently grab the instance lock, so no
103
-
* real ordering issues can occur. In the near future, only
104
-
* hardware devices will grab instance lock which also does not
105
-
* involve any ordering. Suppress lockdep ordering warnings
106
-
* until (if) we start grabbing instance lock on pure SW
107
-
* devices (bond/team/veth/etc).
108
-
*/
109
102
if (a == b)
110
103
return 0;
111
-
return -1;
104
+
105
+
/* Allow locking multiple devices only under rtnl_lock,
106
+
* the exact order doesn't matter.
107
+
* Note that upper devices don't lock their ops, so nesting
108
+
* mostly happens in batched device removal for now.
109
+
*/
110
+
return lockdep_rtnl_is_held() ? -1 : 1;
112
111
}
113
112
114
113
#define netdev_lockdep_set_classes(dev) \