[PATCH 6.1.y] mptcp: disable add_addr retransmission when timeout is 0

From: Geliang Tang tanggeliang@kylinos.cn

[ Upstream commit f5ce0714623cffd00bf2a83e890d09c609b7f50a ]

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-v1-5-521fe99... Signed-off-by: Jakub Kicinski kuba@kernel.org [ Apply to net/mptcp/pm_netlink.c , structural changes in mptcp_pm_alloc_anno_list ] Signed-off-by: Sasha Levin sashal@kernel.org --- Documentation/networking/mptcp-sysctl.rst | 2 ++ net/mptcp/pm_netlink.c | 18 ++++++++++++------ 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/Documentation/networking/mptcp-sysctl.rst b/Documentation/networking/mptcp-sysctl.rst index 213510698014..722b4395e91b 100644 --- a/Documentation/networking/mptcp-sysctl.rst +++ b/Documentation/networking/mptcp-sysctl.rst @@ -20,6 +20,8 @@ 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_netlink.c b/net/mptcp/pm_netlink.c index 3391d4df2dbb..cb92e4b39cf6 100644 --- a/net/mptcp/pm_netlink.c +++ b/net/mptcp/pm_netlink.c @@ -304,6 +304,7 @@ static void mptcp_pm_add_timer(struct timer_list *timer) struct mptcp_pm_add_entry *entry = from_timer(entry, timer, add_timer); struct mptcp_sock *msk = entry->sock; struct sock *sk = (struct sock *)msk; + unsigned int timeout;

pr_debug("msk=%p\n", msk);

@@ -321,6 +322,10 @@ 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)) { @@ -332,7 +337,7 @@ 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);

@@ -374,6 +379,7 @@ 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);

@@ -383,9 +389,7 @@ bool mptcp_pm_alloc_anno_list(struct mptcp_sock *msk, if (WARN_ON_ONCE(mptcp_pm_is_kernel(msk))) return false;

- sk_reset_timer(sk, &add_entry->add_timer, - jiffies + mptcp_get_add_addr_timeout(net)); - return true; + goto reset_timer; }

add_entry = kmalloc(sizeof(*add_entry), GFP_ATOMIC); @@ -399,8 +403,10 @@ bool mptcp_pm_alloc_anno_list(struct mptcp_sock *msk, add_entry->retrans_times = 0;

timer_setup(&add_entry->add_timer, mptcp_pm_add_timer, 0); - sk_reset_timer(sk, &add_entry->add_timer, - jiffies + mptcp_get_add_addr_timeout(net)); +reset_timer: + timeout = mptcp_get_add_addr_timeout(net); + if (timeout) + sk_reset_timer(sk, &add_entry->add_timer, jiffies + timeout);

return true; }