Files
linux/include/linux
Johannes Berg 0b5c21bbc0 net: ensure net_todo_list is processed quickly
In [1], Will raised a potential issue that the cfg80211 code,
which does (from a locking perspective)

  rtnl_lock()
  wiphy_lock()
  rtnl_unlock()

might be suspectible to ABBA deadlocks, because rtnl_unlock()
calls netdev_run_todo(), which might end up calling rtnl_lock()
again, which could then deadlock (see the comment in the code
added here for the scenario).

Some back and forth and thinking ensued, but clearly this can't
happen if the net_todo_list is empty at the rtnl_unlock() here.
Clearly, the code here cannot actually put an entry on it, and
all other users of rtnl_unlock() will empty it since that will
always go through netdev_run_todo(), emptying the list.

So the only other way to get there would be to add to the list
and then unlock the RTNL without going through rtnl_unlock(),
which is only possible through __rtnl_unlock(). However, this
isn't exported and not used in many places, and none of them
seem to be able to unregister before using it.

Therefore, add a WARN_ON() in the code to ensure this invariant
won't be broken, so that the cfg80211 (or any similar) code
stays safe.

[1] https://lore.kernel.org/r/Yjzpo3TfZxtKPMAG@google.com

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Link: https://lore.kernel.org/r/20220404113847.0ee02e4a70da.Ic73d206e217db20fd22dcec14fe5442ca732804b@changeid
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-04-05 14:28:16 -07:00
..
2022-02-27 13:38:10 +00:00
2022-03-23 19:58:38 +01:00
2022-02-01 14:25:50 +02:00
2022-01-22 08:33:34 +02:00
2022-01-15 08:47:31 -08:00
2022-03-08 19:39:38 -07:00
2022-03-17 20:17:18 -07:00
2022-03-11 19:15:03 -08:00
2021-09-08 15:32:35 -07:00
2022-03-15 10:32:44 +01:00
2021-12-10 17:10:55 -08:00
2022-02-07 16:35:35 -08:00
2022-02-07 16:35:35 -08:00
2021-12-10 12:51:28 +01:00
2021-08-26 15:32:28 -04:00
2021-09-06 07:20:56 -04:00
2022-03-16 15:13:36 -07:00
2022-01-15 08:47:31 -08:00
2022-02-13 16:50:07 -08:00
2022-04-01 14:40:44 -04:00
2022-01-20 08:52:54 +02:00
2022-03-02 22:44:49 -08:00
2022-02-28 23:26:27 -08:00
2022-03-15 08:23:29 -04:00
2022-02-28 13:25:49 +01:00
2022-02-19 19:23:53 -08:00
2022-02-14 15:43:15 +01:00
2021-10-05 06:54:16 -05:00
2022-02-05 15:20:34 +00:00
2022-03-18 09:47:04 +01:00
2022-01-27 13:53:26 +00:00
2021-09-30 12:46:44 -06:00
2022-03-21 12:57:38 -04:00
2021-12-16 22:22:20 +01:00
2021-08-23 13:19:12 +02:00
2022-04-01 14:40:44 -04:00
2022-02-09 09:24:40 -05:00
2022-02-28 13:45:04 +02:00
2022-01-12 10:14:09 -06:00
2021-11-16 19:07:53 -08:00
2021-09-17 13:52:17 +01:00
2021-09-27 09:27:29 -04:00
2022-03-24 19:06:45 -07:00
2022-04-01 13:45:08 -04:00
2022-02-02 07:49:59 -07:00
2021-09-27 17:00:21 +02:00
2022-02-09 08:04:44 +01:00
2022-02-09 08:04:44 +01:00
2021-10-14 13:29:18 +02:00
2021-08-18 22:08:24 +02:00
2022-01-22 08:33:37 +02:00
2022-01-08 12:43:57 -06:00
2021-11-18 09:36:39 +01:00
2022-01-24 14:45:02 +01:00
2022-03-08 14:33:36 -06:00
2022-03-17 20:16:29 -07:00
2022-03-23 19:58:41 +01:00
2022-02-24 15:04:51 +00:00
2021-08-19 09:02:55 +09:00
2021-11-03 11:41:25 -07:00
2022-02-25 09:36:06 +01:00
2022-03-07 12:48:35 -07:00
2022-02-16 07:49:41 +01:00
2022-03-22 15:57:11 -07:00
2021-11-25 18:35:23 +01:00
2022-01-26 14:54:48 +01:00
2022-01-27 13:53:27 +00:00
2021-10-12 11:41:39 -03:00
2021-12-30 12:13:04 +01:00
2022-03-28 16:53:00 -04:00
2021-12-09 10:49:56 -08:00
2021-10-19 23:44:30 +08:00