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| author | Eric Dumazet <edumazet@google.com> | 2025-01-14 23:55:30 +0300 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2025-01-16 06:17:04 +0300 |
| commit | ae646f1a0bb97401bac0044bbe2a179a1e38b408 (patch) | |
| tree | 241188fb949f54a1ab0cc9c931f284229c31bf70 | |
| parent | cfa579f6665635b72d4a075fc91eb144c2b0f74e (diff) | |
| download | linux-ae646f1a0bb97401bac0044bbe2a179a1e38b408.tar.xz | |
net: reduce RTNL hold duration in unregister_netdevice_many_notify() (part 1)
Two synchronize_net() calls are currently done while holding RTNL.
This is source of RTNL contention in workloads adding and deleting
many network namespaces per second, because synchronize_rcu()
and synchronize_rcu_expedited() can use 60+ ms in some cases.
For cleanup_net() use, temporarily release RTNL
while calling the last synchronize_net().
This should be safe, because devices are no longer visible
to other threads at this point.
In any case, the new netdev_lock() / netdev_unlock()
infrastructure that we are adding should allow
to fix potential issues, with a combination
of a per-device mutex and dev->reg_state awareness.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jesse Brandeburg <jbrandeburg@cloudflare.com>
Link: https://patch.msgid.link/20250114205531.967841-5-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | net/core/dev.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index d652ea66e575..3924a4af68b8 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -11629,6 +11629,7 @@ void unregister_netdevice_many_notify(struct list_head *head, rtnl_drop_if_cleanup_net(); flush_all_backlogs(); rtnl_acquire_if_cleanup_net(); + /* TODO: move this before the prior rtnl_acquire_if_cleanup_net() */ synchronize_net(); list_for_each_entry(dev, head, unreg_list) { @@ -11689,7 +11690,9 @@ void unregister_netdevice_many_notify(struct list_head *head, #endif } + rtnl_drop_if_cleanup_net(); synchronize_net(); + rtnl_acquire_if_cleanup_net(); list_for_each_entry(dev, head, unreg_list) { netdev_put(dev, &dev->dev_registered_tracker); |