Recently, Paolo fixed a bug where a TCP-specific helper was used with an
MPTCP socket [1]. The bug was not detected by fuzzer or static analysis.

Following this, it has been suggested to add a check, only in debug
mode. This is what this series is doing.

The series has been split to be upstreamed: a preparation patch for
MPTCP, the modification for TCP, then for MPTCP. It is not clear if it
would be OK to add that upstream. If not, we can squash these three
patches in "DO-NOT-MERGE: mptcp: improve code coverage for CI" commit we
have in our export tree.

Note that the MPTCP Token kUnit test needs to be adapted for this new
check. This is what is done in patch 1/3.

Link: https://lore.kernel.org/mptcp/35875ef9cb7194563b580e14c71cc8cb065f846c.1706043786.git.pabeni@redhat.com/ [1]
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
Changes in v3:
- Patch 2 and 3 have been modified, please the changelog on each patch
- Link to v2: https://lore.kernel.org/r/20240201-mptcp-check-protocol-v2-0-1e253ef51990@kernel.org

Changes in v2:
- Patch 2 and 3 have been modified, please the changelog on each patch
- Link to v1: https://lore.kernel.org/r/20240131-mptcp-check-protocol-v1-0-a06067f0bd08@kernel.org

---
Matthieu Baerts (NGI0) (3):
      mptcp: token kunit: set protocol
      mptcp: check the protocol in tcp_sk() with DEBUG_NET
      mptcp: check the protocol in mptcp_sk() with DEBUG_NET

 net/mptcp/protocol.h   | 14 ++++++++++++++
 net/mptcp/token_test.c |  7 ++++++-
 2 files changed, 20 insertions(+), 1 deletion(-)
---
base-commit: c2469b38e369c3f2b9577beeb9470cc757abc1b9
change-id: 20240131-mptcp-check-protocol-e32e53d04a75

Best regards,
-- 
Matthieu Baerts (NGI0) <matttbe@kernel.org>