mptcp: disable add_addr retransmission when timeout is 0

When add_addr_timeout was set to 0, this caused the ADD_ADDR to be
retransmitted immediately, which looks like a buggy behaviour. Instead,
interpret 0 as "no retransmissions needed".

The documentation is updated to explicitly state that setting the timeout
to 0 disables retransmission.

Fixes: 93f323b9cccc ("mptcp: add a new sysctl add_addr_timeout")
Cc: stable@vger.kernel.org
Suggested-by: Matthieu Baerts <matttbe@kernel.org>
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20250815-net-mptcp-misc-fixes-6-17-rc2-v1-5-521fe9957892@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/Documentation/networking/mptcp-sysctl.rst b/Documentation/networking/mptcp-sysctl.rst
index 5bfab01eff5a9db89e1484787953241c16e147cf..1683c139821e3ba6d9eaa3c59330a523d29f1164 100644 (file)
--- a/Documentation/networking/mptcp-sysctl.rst
+++ b/Documentation/networking/mptcp-sysctl.rst
@@ -12,6 +12,8 @@ add_addr_timeout - INTEGER (seconds)
        resent to an MPTCP peer that has not acknowledged a previous
        ADD_ADDR message.
 
+       Do not retransmit if set to 0.
+
        The default value matches TCP_RTO_MAX. This is a per-namespace
        sysctl.
 

diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
index c5f6a53ce5f1e10dada52865e41b685d888a71fa..136a380602cae872b76560649c924330e5f42533 100644 (file)
--- a/net/mptcp/pm.c
+++ b/net/mptcp/pm.c
@@ -274,6 +274,7 @@ static void mptcp_pm_add_timer(struct timer_list *timer)
                                                              add_timer);
        struct mptcp_sock *msk = entry->sock;
        struct sock *sk = (struct sock *)msk;
+       unsigned int timeout;
 
        pr_debug("msk=%p\n", msk);
 
@@ -291,6 +292,10 @@ static void mptcp_pm_add_timer(struct timer_list *timer)
                goto out;
        }
 
+       timeout = mptcp_get_add_addr_timeout(sock_net(sk));
+       if (!timeout)
+               goto out;
+
        spin_lock_bh(&msk->pm.lock);
 
        if (!mptcp_pm_should_add_signal_addr(msk)) {
@@ -302,7 +307,7 @@ static void mptcp_pm_add_timer(struct timer_list *timer)
 
        if (entry->retrans_times < ADD_ADDR_RETRANS_MAX)
                sk_reset_timer(sk, timer,
-                              jiffies + mptcp_get_add_addr_timeout(sock_net(sk)));
+                              jiffies + timeout);
 
        spin_unlock_bh(&msk->pm.lock);
 
@@ -344,6 +349,7 @@ bool mptcp_pm_alloc_anno_list(struct mptcp_sock *msk,
        struct mptcp_pm_add_entry *add_entry = NULL;
        struct sock *sk = (struct sock *)msk;
        struct net *net = sock_net(sk);
+       unsigned int timeout;
 
        lockdep_assert_held(&msk->pm.lock);
 
@@ -368,8 +374,9 @@ bool mptcp_pm_alloc_anno_list(struct mptcp_sock *msk,
 
        timer_setup(&add_entry->add_timer, mptcp_pm_add_timer, 0);
 reset_timer:
-       sk_reset_timer(sk, &add_entry->add_timer,
-                      jiffies + mptcp_get_add_addr_timeout(net));
+       timeout = mptcp_get_add_addr_timeout(net);
+       if (timeout)
+               sk_reset_timer(sk, &add_entry->add_timer, jiffies + timeout);
 
        return true;
 }