net/mptcp/sockopt.c | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+)
The IPV6_TCLASS setsockopt just needs to be forwarded to the individual
TCP sockets, like IP_TOS is already handled for IPv4. The code here is
pretty much identical, except there's no helper for IPv6 like IPv4's
__ip_sock_set_tos().
Coincidentally, ssh uses this sockopt and prints an error in the middle
of your ongoing SSH session when it doesn't work (very annoying when
doing SCP/SFTP on a multiplexed session.)
Signed-off-by: David 'equinox' Lamparter <equinox@diac24.net>
Cc: Matthieu Baerts <matttbe@kernel.org>
Cc: Mat Martineau <martineau@kernel.org>
Cc: Geliang Tang <geliang@kernel.org>
---
note: I wasn't entirely sure what tree this should be on top of, with the
mptcp trees on github & kernel.org; this is on top of net-next. It
shouldn't really matter though.
---
net/mptcp/sockopt.c | 34 ++++++++++++++++++++++++++++++++++
1 file changed, 34 insertions(+)
diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c
index fcf6feb2a9eb..edddafebb8de 100644
--- a/net/mptcp/sockopt.c
+++ b/net/mptcp/sockopt.c
@@ -394,6 +394,35 @@ static int mptcp_setsockopt_sol_socket(struct mptcp_sock *msk, int optname,
return -EOPNOTSUPP;
}
+static int mptcp_setsockopt_v6_set_tclass(struct mptcp_sock *msk, int optname,
+ sockptr_t optval, unsigned int optlen)
+{
+ struct mptcp_subflow_context *subflow;
+ struct sock *sk = (struct sock *)msk;
+ int err, val;
+
+ err = ipv6_setsockopt(sk, SOL_IPV6, optname, optval, optlen);
+
+ if (err != 0)
+ return err;
+
+ lock_sock(sk);
+ sockopt_seq_inc(msk);
+ val = READ_ONCE(inet6_sk(sk)->tclass);
+ mptcp_for_each_subflow(msk, subflow) {
+ struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
+ bool slow;
+
+ slow = lock_sock_fast(ssk);
+ inet6_sk(ssk)->tclass = val;
+ sk_dst_reset(ssk);
+ unlock_sock_fast(ssk, slow);
+ }
+ release_sock(sk);
+
+ return 0;
+}
+
static int mptcp_setsockopt_v6(struct mptcp_sock *msk, int optname,
sockptr_t optval, unsigned int optlen)
{
@@ -436,6 +465,8 @@ static int mptcp_setsockopt_v6(struct mptcp_sock *msk, int optname,
release_sock(sk);
break;
+ case IPV6_TCLASS:
+ return mptcp_setsockopt_v6_set_tclass(msk, optname, optval, optlen);
}
return ret;
@@ -1485,6 +1516,9 @@ static int mptcp_getsockopt_v6(struct mptcp_sock *msk, int optname,
struct sock *sk = (void *)msk;
switch (optname) {
+ case IPV6_TCLASS:
+ return mptcp_put_int_option(msk, optval, optlen,
+ READ_ONCE(inet6_sk(sk)->tclass));
case IPV6_V6ONLY:
return mptcp_put_int_option(msk, optval, optlen,
sk->sk_ipv6only);
--
2.53.0Hi David, kernel test robot noticed the following build errors: [auto build test ERROR on net-next/main] url: https://github.com/intel-lab-lkp/linux/commits/David-equinox-Lamparter/mptcp-sockopt-implement-IPV6_TCLASS/20260713-162825 base: net-next/main patch link: https://lore.kernel.org/r/20260713080634.296011-1-equinox%40diac24.net patch subject: [PATCH net-next] mptcp: sockopt: implement IPV6_TCLASS config: x86_64-kexec (https://download.01.org/0day-ci/archive/20260713/202607131605.i02odG4b-lkp@intel.com/config) compiler: clang version 22.1.8 (https://github.com/llvm/llvm-project ca7933e47d3a3451d81e72ac174dcb5aa28b59d1) reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260713/202607131605.i02odG4b-lkp@intel.com/reproduce) If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot <lkp@intel.com> | Closes: https://lore.kernel.org/oe-kbuild-all/202607131605.i02odG4b-lkp@intel.com/ All errors (new ones prefixed by >>): >> ld.lld: error: undefined symbol: ipv6_setsockopt >>> referenced by sockopt.c:404 (net/mptcp/sockopt.c:404) >>> vmlinux.o:(mptcp_setsockopt) -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests/wiki
Hi David, kernel test robot noticed the following build errors: [auto build test ERROR on net-next/main] url: https://github.com/intel-lab-lkp/linux/commits/David-equinox-Lamparter/mptcp-sockopt-implement-IPV6_TCLASS/20260713-162825 base: net-next/main patch link: https://lore.kernel.org/r/20260713080634.296011-1-equinox%40diac24.net patch subject: [PATCH net-next] mptcp: sockopt: implement IPV6_TCLASS config: sparc-randconfig-001 (https://download.01.org/0day-ci/archive/20260713/202607132109.n8GCw6cD-lkp@intel.com/config) compiler: sparc-linux-gcc (GCC) 16.1.0 reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260713/202607132109.n8GCw6cD-lkp@intel.com/reproduce) If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot <lkp@intel.com> | Closes: https://lore.kernel.org/oe-kbuild-all/202607132109.n8GCw6cD-lkp@intel.com/ All errors (new ones prefixed by >>): sparc-linux-ld: net/mptcp/sockopt.o: in function `mptcp_setsockopt_v6': >> sockopt.c:(.text+0x908): undefined reference to `ipv6_setsockopt' -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests/wiki
On Mon, Jul 13, 2026 at 09:24:52PM +0800, kernel test robot wrote: > sparc-linux-ld: net/mptcp/sockopt.o: in function `mptcp_setsockopt_v6': > >> sockopt.c:(.text+0x908): undefined reference to `ipv6_setsockopt' Oops. Forgot IPv6 can still be disabled. v2 in a few minutes.
© 2016 - 2026 Red Hat, Inc.