netdev - [PATCH v2 net-next 3/4] inetpeer: update inetpeer timestamp in inet

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Message-ID: <20241215175629.1248773-4-edumazet@google.com>
Date: Sun, 15 Dec 2024 17:56:28 +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: netdev@...r.kernel.org, Simon Horman <horms@...nel.org>, 
	Ido Schimmel <idosch@...dia.com>, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH v2 net-next 3/4] inetpeer: update inetpeer timestamp in inet_getpeer()

inet_putpeer() will be removed in the following patch,
because we will no longer use refcounts.

Update inetpeer timestamp (p->dtime) at lookup time.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/ipv4/inetpeer.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/net/ipv4/inetpeer.c b/net/ipv4/inetpeer.c
index bc79cc9d13ebb4691660f51babbc748900b8f6db..28c3ae5bc4a0b62030bd190dbe5284632ea23efd 100644
--- a/net/ipv4/inetpeer.c
+++ b/net/ipv4/inetpeer.c
@@ -95,6 +95,7 @@ static struct inet_peer *lookup(const struct inetpeer_addr *daddr,
 {
 	struct rb_node **pp, *parent, *next;
 	struct inet_peer *p;
+	u32 now;
 
 	pp = &base->rb_root.rb_node;
 	parent = NULL;
@@ -110,6 +111,9 @@ static struct inet_peer *lookup(const struct inetpeer_addr *daddr,
 		if (cmp == 0) {
 			if (!refcount_inc_not_zero(&p->refcnt))
 				break;
+			now = jiffies;
+			if (READ_ONCE(p->dtime) != now)
+				WRITE_ONCE(p->dtime, now);
 			return p;
 		}
 		if (gc_stack) {
@@ -150,9 +154,6 @@ static void inet_peer_gc(struct inet_peer_base *base,
 	for (i = 0; i < gc_cnt; i++) {
 		p = gc_stack[i];
 
-		/* The READ_ONCE() pairs with the WRITE_ONCE()
-		 * in inet_putpeer()
-		 */
 		delta = (__u32)jiffies - READ_ONCE(p->dtime);
 
 		if (delta < ttl || !refcount_dec_if_one(&p->refcnt))
@@ -224,11 +225,6 @@ EXPORT_SYMBOL_GPL(inet_getpeer);
 
 void inet_putpeer(struct inet_peer *p)
 {
-	/* The WRITE_ONCE() pairs with itself (we run lockless)
-	 * and the READ_ONCE() in inet_peer_gc()
-	 */
-	WRITE_ONCE(p->dtime, (__u32)jiffies);
-
 	if (refcount_dec_and_test(&p->refcnt))
 		kfree_rcu(p, rcu);
 }
-- 
2.47.1.613.gc27f4b7a9f-goog