| Message ID | 20241204210234.319484-1-edumazet@google.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 6c36b5c244d6cb22ef8ea2f6b5da46f5171b37a5 |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net-next] net: tipc: remove one synchronize_net() from tipc_nametbl_stop() | expand |
Hello: This patch was applied to netdev/net-next.git (main) by Jakub Kicinski <kuba@kernel.org>: On Wed, 4 Dec 2024 21:02:34 +0000 you wrote: > tipc_exit_net() is very slow and is abused by syzbot. > > tipc_nametbl_stop() is called for each netns being dismantled. > > Calling synchronize_net() right before freeing tn->nametbl > is a big hammer. > > [...] Here is the summary with links: - [net-next] net: tipc: remove one synchronize_net() from tipc_nametbl_stop() https://git.kernel.org/netdev/net-next/c/6c36b5c244d6 You are awesome, thank you!
diff --git a/net/tipc/name_table.c b/net/tipc/name_table.c index d1180370fdf41cb05c86522b4da6aa412a54cce9..e74940eab3a47901d49b552767b16793c4459aa2 100644 --- a/net/tipc/name_table.c +++ b/net/tipc/name_table.c @@ -949,8 +949,8 @@ void tipc_nametbl_stop(struct net *net) } spin_unlock_bh(&tn->nametbl_lock); - synchronize_net(); - kfree(nt); + /* TODO: clear tn->nametbl, implement proper RCU rules ? */ + kfree_rcu(nt, rcu); } static int __tipc_nl_add_nametable_publ(struct tipc_nl_msg *msg, diff --git a/net/tipc/name_table.h b/net/tipc/name_table.h index 3bcd9ef8cee3046f09b07901b87e344f42253d69..7ff6eeebaae643c31f8395cb14d3b6b8d8cd2610 100644 --- a/net/tipc/name_table.h +++ b/net/tipc/name_table.h @@ -90,6 +90,7 @@ struct publication { /** * struct name_table - table containing all existing port name publications + * @rcu: RCU callback head used for deferred freeing * @services: name sequence hash lists * @node_scope: all local publications with node scope * - used by name_distr during re-init of name table @@ -102,6 +103,7 @@ struct publication { * @snd_nxt: next sequence number to be used */ struct name_table { + struct rcu_head rcu; struct hlist_head services[TIPC_NAMETBL_SIZE]; struct list_head node_scope; struct list_head cluster_scope;
tipc_exit_net() is very slow and is abused by syzbot. tipc_nametbl_stop() is called for each netns being dismantled. Calling synchronize_net() right before freeing tn->nametbl is a big hammer. Replace this with kfree_rcu(). Note that RCU is not properly used here, otherwise tn->nametbl should be cleared before the synchronize_net() or kfree_rcu(), or even before the cleanup loop. We might need to fix this at some point. Also note tipc uses other synchronize_rcu() calls, more work is needed to make tipc_exit_net() much faster. List of remaining calls to synchronize_rcu() tipc_detach_loopback() (dev_remove_pack()) tipc_bcast_stop() tipc_sk_rht_destroy() Signed-off-by: Eric Dumazet <edumazet@google.com> --- Cc: Jon Maloy <jmaloy@redhat.com> Cc: Ying Xue <ying.xue@windriver.com> Cc: tipc-discussion@lists.sourceforge.net --- net/tipc/name_table.c | 4 ++-- net/tipc/name_table.h | 2 ++ 2 files changed, 4 insertions(+), 2 deletions(-)