tjh.dev / kernel
Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
1
fork

Configure Feed

Select the types of activity you want to include in your feed.

net: tipc: remove one synchronize_net() from tipc_nametbl_stop()

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>
Link: https://patch.msgid.link/20241204210234.319484-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

authored by

Eric Dumazet and committed by
Jakub Kicinski 6c36b5c2 e36d46b9

+4 -2
+2 -2
net/tipc/name_table.c
··· 949 949 } 950 950 spin_unlock_bh(&tn->nametbl_lock); 951 951 952 - synchronize_net(); 953 - kfree(nt); 952 + /* TODO: clear tn->nametbl, implement proper RCU rules ? */ 953 + kfree_rcu(nt, rcu); 954 954 } 955 955 956 956 static int __tipc_nl_add_nametable_publ(struct tipc_nl_msg *msg,
+2
net/tipc/name_table.h
··· 90 90 91 91 /** 92 92 * struct name_table - table containing all existing port name publications 93 + * @rcu: RCU callback head used for deferred freeing 93 94 * @services: name sequence hash lists 94 95 * @node_scope: all local publications with node scope 95 96 * - used by name_distr during re-init of name table ··· 103 102 * @snd_nxt: next sequence number to be used 104 103 */ 105 104 struct name_table { 105 + struct rcu_head rcu; 106 106 struct hlist_head services[TIPC_NAMETBL_SIZE]; 107 107 struct list_head node_scope; 108 108 struct list_head cluster_scope;