netdev - [PATCH net-next 9/9] inet_diag: skip over empty buckets

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Message-ID: <20240122112603.3270097-10-edumazet@google.com>
Date: Mon, 22 Jan 2024 11:26:03 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: David Ahern <dsahern@...nel.org>, Kuniyuki Iwashima <kuniyu@...zon.com>, 
	Martin KaFai Lau <kafai@...com>, Guillaume Nault <gnault@...hat.com>, netdev@...r.kernel.org, 
	eric.dumazet@...il.com, Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next 9/9] inet_diag: skip over empty buckets

After the removal of inet_diag_table_mutex, sock_diag_table_mutex
and sock_diag_mutex, I was able so see spinlock contention from
inet_diag_dump_icsk() when running 100 parallel invocations.

It is time to skip over empty buckets.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/ipv4/inet_diag.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c
index 2c2d8b9dd8e9bb502e52e30dffc70da36d9b1c74..7adace541fe292851a66ccc4de1da2a60ac4714e 100644
--- a/net/ipv4/inet_diag.c
+++ b/net/ipv4/inet_diag.c
@@ -1045,6 +1045,10 @@ void inet_diag_dump_icsk(struct inet_hashinfo *hashinfo, struct sk_buff *skb,
 			num = 0;
 			ilb = &hashinfo->lhash2[i];
 
+			if (hlist_nulls_empty(&ilb->nulls_head)) {
+				s_num = 0;
+				continue;
+			}
 			spin_lock(&ilb->lock);
 			sk_nulls_for_each(sk, node, &ilb->nulls_head) {
 				struct inet_sock *inet = inet_sk(sk);
@@ -1109,6 +1113,10 @@ void inet_diag_dump_icsk(struct inet_hashinfo *hashinfo, struct sk_buff *skb,
 			accum = 0;
 			ibb = &hashinfo->bhash2[i];
 
+			if (hlist_empty(&ibb->chain)) {
+				s_num = 0;
+				continue;
+			}
 			spin_lock_bh(&ibb->lock);
 			inet_bind_bucket_for_each(tb2, &ibb->chain) {
 				if (!net_eq(ib2_net(tb2), net))
-- 
2.43.0.429.g432eaa2c6b-goog