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From:   Artem Savkov <asavkov@redhat.com>
To:     tglx@linutronix.de, jpoimboe@redhat.com, netdev@vger.kernel.org
Cc:     davem@davemloft.net, yoshfuji@linux-ipv6.org, dsahern@kernel.org,
        linux-kernel@vger.kernel.org, Artem Savkov <asavkov@redhat.com>
Subject: [PATCH v2 2/2] net: make tcp keepalive timer upper bound
Date:   Thu, 24 Mar 2022 10:15:00 +0100
Message-Id: <20220324091500.2638745-3-asavkov@redhat.com>
In-Reply-To: <20220324091500.2638745-1-asavkov@redhat.com>
References: <20220323184026.wkj55y55jbeumngs@treble>
 <20220324091500.2638745-1-asavkov@redhat.com>
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Make sure TCP keepalive timer does not expire late. Switching to upper
bound timers means it can fire off early but in case of keepalive
tcp_keepalive_timer() handler checks elapsed time and resets the timer
if it was triggered early. This results in timer "cascading" to a
higher precision and being just a couple of milliseconds off it's
original mark.

Signed-off-by: Artem Savkov <asavkov@redhat.com>
---
 net/ipv4/inet_connection_sock.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index fc2a985f6064..a8fea958960b 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -564,7 +564,7 @@ void inet_csk_init_xmit_timers(struct sock *sk,
 
 	timer_setup(&icsk->icsk_retransmit_timer, retransmit_handler, 0);
 	timer_setup(&icsk->icsk_delack_timer, delack_handler, 0);
-	timer_setup(&sk->sk_timer, keepalive_handler, 0);
+	timer_setup(&sk->sk_timer, keepalive_handler, TIMER_UPPER_BOUND);
 	icsk->icsk_pending = icsk->icsk_ack.pending = 0;
 }
 EXPORT_SYMBOL(inet_csk_init_xmit_timers);
-- 
2.34.1