This change records the 'server_side' attribute of MPTCP_EVENT_CREATED
and MPTCP_EVENT_ESTABLISHED events to inform their recipient about the
Client/Server role of the running MPTCP application.

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/246
Signed-off-by: Kishen Maloor <kishen.maloor@intel.com>
---
 include/uapi/linux/mptcp.h | 1 +
 net/mptcp/pm_netlink.c     | 3 +++
 2 files changed, 4 insertions(+)

diff --git a/include/uapi/linux/mptcp.h b/include/uapi/linux/mptcp.h
index 9690efedb5fa..e41ea01a94bb 100644
--- a/include/uapi/linux/mptcp.h
+++ b/include/uapi/linux/mptcp.h
@@ -188,6 +188,7 @@ enum mptcp_event_attr {
 	MPTCP_ATTR_IF_IDX,	/* s32 */
 	MPTCP_ATTR_RESET_REASON,/* u32 */
 	MPTCP_ATTR_RESET_FLAGS, /* u32 */
+	MPTCP_ATTR_SERVER_SIDE,	/* u8 */
 
 	__MPTCP_ATTR_AFTER_LAST
 };
diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index 905f451ff0f9..6fb84f9c377f 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -1974,6 +1974,9 @@ static int mptcp_event_created(struct sk_buff *skb,
 	if (err)
 		return err;
 
+	if (nla_put_u8(skb, MPTCP_ATTR_SERVER_SIDE, READ_ONCE(msk->pm.server_side)))
+		return -EMSGSIZE;
+
 	return mptcp_event_add_subflow(skb, ssk);
 }
 
-- 
2.31.1

Hi Kishen,

Thank you for your modifications, that's great!

Our CI did some validations and here is its report:

- KVM Validation: normal:
  - Success! ✅:
  - Task: https://cirrus-ci.com/task/6641200433201152
  - Summary: https://api.cirrus-ci.com/v1/artifact/task/6641200433201152/summary/summary.txt

- KVM Validation: debug:
  - Unstable: 1 failed test(s): selftest_diag 🔴:
  - Task: https://cirrus-ci.com/task/6079457634025472
  - Summary: https://api.cirrus-ci.com/v1/artifact/task/6079457634025472/summary/summary.txt

Initiator: Patchew Applier
Commits: https://github.com/multipath-tcp/mptcp_net-next/commits/3e17c518d8ab

Please note that despite all the efforts that have been already done to have a
stable tests suite when executed on a public CI like here, it is possible some
reported issues are not due to your modifications. Still, do not hesitate to
help us improve that ;-)

Cheers,
MPTCP GH Action bot
Bot operated by Matthieu Baerts (Tessares)