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authorKuniyuki Iwashima <kuniyu@amazon.com>2022-09-07 18:10:21 -0700
committerJakub Kicinski <kuba@kernel.org>2022-09-20 10:21:50 -0700
commitedc12f032a5a1633474db566878ce0012e7ca2f5 (patch)
treeb63f19cc61d23c9e24297a3471e68d7f37ced776
parent4461568aa4e565de2c336f4875ddf912f26da8a5 (diff)
tcp: Save unnecessary inet_twsk_purge() calls.
While destroying netns, we call inet_twsk_purge() in tcp_sk_exit_batch() and tcpv6_net_exit_batch() for AF_INET and AF_INET6. These commands trigger the kernel to walk through the potentially big ehash twice even though the netns has no TIME_WAIT sockets. # ip netns add test # ip netns del test or # unshare -n /bin/true >/dev/null When tw_refcount is 1, we need not call inet_twsk_purge() at least for the net. We can save such unneeded iterations if all netns in net_exit_list have no TIME_WAIT sockets. This change eliminates the tax by the additional unshare() described in the next patch to guarantee the per-netns ehash size. Tested: # mount -t debugfs none /sys/kernel/debug/ # echo cleanup_net > /sys/kernel/debug/tracing/set_ftrace_filter # echo inet_twsk_purge >> /sys/kernel/debug/tracing/set_ftrace_filter # echo function > /sys/kernel/debug/tracing/current_tracer # cat ./add_del_unshare.sh for i in `seq 1 40` do (for j in `seq 1 100` ; do unshare -n /bin/true >/dev/null ; done) & done wait; # ./add_del_unshare.sh Before the patch: # cat /sys/kernel/debug/tracing/trace_pipe kworker/u128:0-8 [031] ...1. 174.162765: cleanup_net <-process_one_work kworker/u128:0-8 [031] ...1. 174.240796: inet_twsk_purge <-cleanup_net kworker/u128:0-8 [032] ...1. 174.244759: inet_twsk_purge <-tcp_sk_exit_batch kworker/u128:0-8 [034] ...1. 174.290861: cleanup_net <-process_one_work kworker/u128:0-8 [039] ...1. 175.245027: inet_twsk_purge <-cleanup_net kworker/u128:0-8 [046] ...1. 175.290541: inet_twsk_purge <-tcp_sk_exit_batch kworker/u128:0-8 [037] ...1. 175.321046: cleanup_net <-process_one_work kworker/u128:0-8 [024] ...1. 175.941633: inet_twsk_purge <-cleanup_net kworker/u128:0-8 [025] ...1. 176.242539: inet_twsk_purge <-tcp_sk_exit_batch After: # cat /sys/kernel/debug/tracing/trace_pipe kworker/u128:0-8 [038] ...1. 428.116174: cleanup_net <-process_one_work kworker/u128:0-8 [038] ...1. 428.262532: cleanup_net <-process_one_work kworker/u128:0-8 [030] ...1. 429.292645: cleanup_net <-process_one_work Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
-rw-r--r--include/net/tcp.h1
-rw-r--r--net/ipv4/tcp_ipv4.c2
-rw-r--r--net/ipv4/tcp_minisocks.c15
-rw-r--r--net/ipv6/tcp_ipv6.c2
4 files changed, 18 insertions, 2 deletions
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 735e957f7f4b..27e8d378c70a 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -346,6 +346,7 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff *skb);
void tcp_rcv_space_adjust(struct sock *sk);
int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
void tcp_twsk_destructor(struct sock *sk);
+void tcp_twsk_purge(struct list_head *net_exit_list, int family);
ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
struct pipe_inode_info *pipe, size_t len,
unsigned int flags);
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 9aa186af6c44..73e6854ea662 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -3206,7 +3206,7 @@ static void __net_exit tcp_sk_exit_batch(struct list_head *net_exit_list)
{
struct net *net;
- inet_twsk_purge(&tcp_hashinfo, AF_INET);
+ tcp_twsk_purge(net_exit_list, AF_INET);
list_for_each_entry(net, net_exit_list, exit_list) {
WARN_ON_ONCE(!refcount_dec_and_test(&net->ipv4.tcp_death_row.tw_refcount));
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 2e53981252d9..98c576d4b671 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -347,6 +347,21 @@ void tcp_twsk_destructor(struct sock *sk)
}
EXPORT_SYMBOL_GPL(tcp_twsk_destructor);
+void tcp_twsk_purge(struct list_head *net_exit_list, int family)
+{
+ struct net *net;
+
+ list_for_each_entry(net, net_exit_list, exit_list) {
+ /* The last refcount is decremented in tcp_sk_exit_batch() */
+ if (refcount_read(&net->ipv4.tcp_death_row.tw_refcount) == 1)
+ continue;
+
+ inet_twsk_purge(&tcp_hashinfo, family);
+ break;
+ }
+}
+EXPORT_SYMBOL_GPL(tcp_twsk_purge);
+
/* Warning : This function is called without sk_listener being locked.
* Be sure to read socket fields once, as their value could change under us.
*/
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index f9ed47eb9b93..06beed4e23bf 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -2229,7 +2229,7 @@ static void __net_exit tcpv6_net_exit(struct net *net)
static void __net_exit tcpv6_net_exit_batch(struct list_head *net_exit_list)
{
- inet_twsk_purge(&tcp_hashinfo, AF_INET6);
+ tcp_twsk_purge(net_exit_list, AF_INET6);
}
static struct pernet_operations tcpv6_net_ops = {