[PATCH v2 mptcp-net 0/2] mptcp: fix missing close transition

[PATCH v2 mptcp-net 0/2] mptcp: fix missing close transition

[Paolo Abeni]

This is an attempt to address the 2nd issue reported in:

https://github.com/multipath-tcp/mptcp_net-next/issues/427

See the individual patch changelog for the details. The cover letter
is here mainly to trigger the CI.

v1 -> v2:
 - fix compile warning reported by the CI

Paolo Abeni (2):
  mptcp: move __mptcp_error_report in protocol.c
  mptcp: process pending subflow error on close

 net/mptcp/protocol.c | 41 +++++++++++++++++++++++++++++++++++++++++
 net/mptcp/subflow.c  | 36 ------------------------------------
 2 files changed, 41 insertions(+), 36 deletions(-)

-- 
2.41.0

[PATCH v2 mptcp-net 1/2] mptcp: move __mptcp_error_report in protocol.c

[Paolo Abeni]

This will simplify the next patch. No functional change intended.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
 net/mptcp/protocol.c | 36 ++++++++++++++++++++++++++++++++++++
 net/mptcp/subflow.c  | 36 ------------------------------------
 2 files changed, 36 insertions(+), 36 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index ab3aaf6cacc5..12d3b575ceba 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -764,6 +764,42 @@ static bool __mptcp_ofo_queue(struct mptcp_sock *msk)
 	return moved;
 }
 
+void __mptcp_error_report(struct sock *sk)
+{
+	struct mptcp_subflow_context *subflow;
+	struct mptcp_sock *msk = mptcp_sk(sk);
+
+	mptcp_for_each_subflow(msk, subflow) {
+		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
+		int err = sock_error(ssk);
+		int ssk_state;
+
+		if (!err)
+			continue;
+
+		/* only propagate errors on fallen-back sockets or
+		 * on MPC connect
+		 */
+		if (sk->sk_state != TCP_SYN_SENT && !__mptcp_check_fallback(msk))
+			continue;
+
+		/* We need to propagate only transition to CLOSE state.
+		 * Orphaned socket will see such state change via
+		 * subflow_sched_work_if_closed() and that path will properly
+		 * destroy the msk as needed.
+		 */
+		ssk_state = inet_sk_state_load(ssk);
+		if (ssk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DEAD))
+			inet_sk_state_store(sk, ssk_state);
+		WRITE_ONCE(sk->sk_err, -err);
+
+		/* This barrier is coupled with smp_rmb() in mptcp_poll() */
+		smp_wmb();
+		sk_error_report(sk);
+		break;
+	}
+}
+
 /* In most cases we will be able to lock the mptcp socket.  If its already
  * owned, we need to defer to the work queue to avoid ABBA deadlock.
  */
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 9bf3c7bc1762..2f40c23fdb0d 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -1362,42 +1362,6 @@ void mptcp_space(const struct sock *ssk, int *space, int *full_space)
 	*full_space = mptcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf));
 }
 
-void __mptcp_error_report(struct sock *sk)
-{
-	struct mptcp_subflow_context *subflow;
-	struct mptcp_sock *msk = mptcp_sk(sk);
-
-	mptcp_for_each_subflow(msk, subflow) {
-		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
-		int err = sock_error(ssk);
-		int ssk_state;
-
-		if (!err)
-			continue;
-
-		/* only propagate errors on fallen-back sockets or
-		 * on MPC connect
-		 */
-		if (sk->sk_state != TCP_SYN_SENT && !__mptcp_check_fallback(msk))
-			continue;
-
-		/* We need to propagate only transition to CLOSE state.
-		 * Orphaned socket will see such state change via
-		 * subflow_sched_work_if_closed() and that path will properly
-		 * destroy the msk as needed.
-		 */
-		ssk_state = inet_sk_state_load(ssk);
-		if (ssk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DEAD))
-			inet_sk_state_store(sk, ssk_state);
-		WRITE_ONCE(sk->sk_err, -err);
-
-		/* This barrier is coupled with smp_rmb() in mptcp_poll() */
-		smp_wmb();
-		sk_error_report(sk);
-		break;
-	}
-}
-
 static void subflow_error_report(struct sock *ssk)
 {
 	struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
-- 
2.41.0

[PATCH v2 mptcp-net 2/2] mptcp: process pending subflow error on close

[Paolo Abeni]

On incoming TCP reset, subflow closing could happen before error
propagation. That in turn could cause the socket error being ignored,
and a missing socket state transition, as reported by Daire-Byrne.

Address the issues explicitly checking for subflow socket error at
close time. To avoid code duplication, factor-out of __mptcp_error_report()
a new helper implementing the relevant bits.

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/429
Fixes: 15cc10453398 ("mptcp: deliver ssk errors to msk")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
v1 -> v2:
 - fix compile warning
---
 net/mptcp/protocol.c | 63 ++++++++++++++++++++++++--------------------
 1 file changed, 34 insertions(+), 29 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 12d3b575ceba..357030f40cef 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -764,40 +764,44 @@ static bool __mptcp_ofo_queue(struct mptcp_sock *msk)
 	return moved;
 }
 
-void __mptcp_error_report(struct sock *sk)
+static bool __mptcp_subflow_error_report(struct sock *sk, struct sock *ssk)
 {
-	struct mptcp_subflow_context *subflow;
-	struct mptcp_sock *msk = mptcp_sk(sk);
+	int err = sock_error(ssk);
+	int ssk_state;
 
-	mptcp_for_each_subflow(msk, subflow) {
-		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
-		int err = sock_error(ssk);
-		int ssk_state;
+	if (!err)
+		return false;
 
-		if (!err)
-			continue;
+	/* only propagate errors on fallen-back sockets or
+	 * on MPC connect
+	 */
+	if (sk->sk_state != TCP_SYN_SENT && !__mptcp_check_fallback(mptcp_sk(sk)))
+		return false;
 
-		/* only propagate errors on fallen-back sockets or
-		 * on MPC connect
-		 */
-		if (sk->sk_state != TCP_SYN_SENT && !__mptcp_check_fallback(msk))
-			continue;
+	/* We need to propagate only transition to CLOSE state.
+	 * Orphaned socket will see such state change via
+	 * subflow_sched_work_if_closed() and that path will properly
+	 * destroy the msk as needed.
+	 */
+	ssk_state = inet_sk_state_load(ssk);
+	if (ssk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DEAD))
+		inet_sk_state_store(sk, ssk_state);
+	WRITE_ONCE(sk->sk_err, -err);
 
-		/* We need to propagate only transition to CLOSE state.
-		 * Orphaned socket will see such state change via
-		 * subflow_sched_work_if_closed() and that path will properly
-		 * destroy the msk as needed.
-		 */
-		ssk_state = inet_sk_state_load(ssk);
-		if (ssk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DEAD))
-			inet_sk_state_store(sk, ssk_state);
-		WRITE_ONCE(sk->sk_err, -err);
-
-		/* This barrier is coupled with smp_rmb() in mptcp_poll() */
-		smp_wmb();
-		sk_error_report(sk);
-		break;
-	}
+	/* This barrier is coupled with smp_rmb() in mptcp_poll() */
+	smp_wmb();
+	sk_error_report(sk);
+	return true;
+}
+
+void __mptcp_error_report(struct sock *sk)
+{
+	struct mptcp_subflow_context *subflow;
+	struct mptcp_sock *msk = mptcp_sk(sk);
+
+	mptcp_for_each_subflow(msk, subflow)
+		if (__mptcp_subflow_error_report(sk, mptcp_subflow_tcp_sock(subflow)))
+			break;
 }
 
 /* In most cases we will be able to lock the mptcp socket.  If its already
@@ -2422,6 +2426,7 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
 	}
 
 out_release:
+	__mptcp_subflow_error_report(sk, ssk);
 	release_sock(ssk);
 
 	sock_put(ssk);
-- 
2.41.0

Re: mptcp: process pending subflow error on close: Tests Results

[MPTCP CI]

Hi Paolo,

Thank you for your modifications, that's great!

Our CI did some validations and here is its report:

- KVM Validation: normal (except selftest_mptcp_join):
  - Success! ✅:
  - Task: https://cirrus-ci.com/task/5564860235251712
  - Summary: https://api.cirrus-ci.com/v1/artifact/task/5564860235251712/summary/summary.txt

- KVM Validation: debug (except selftest_mptcp_join):
  - Success! ✅:
  - Task: https://cirrus-ci.com/task/4544513444675584
  - Summary: https://api.cirrus-ci.com/v1/artifact/task/4544513444675584/summary/summary.txt

- KVM Validation: debug (only selftest_mptcp_join):
  - Success! ✅:
  - Task: https://cirrus-ci.com/task/5670413351518208
  - Summary: https://api.cirrus-ci.com/v1/artifact/task/5670413351518208/summary/summary.txt

- KVM Validation: normal (only selftest_mptcp_join):
  - Success! ✅:
  - Task: https://cirrus-ci.com/task/6690760142094336
  - Summary: https://api.cirrus-ci.com/v1/artifact/task/6690760142094336/summary/summary.txt

Initiator: Patchew Applier
Commits: https://github.com/multipath-tcp/mptcp_net-next/commits/e64f9b400ebc


If there are some issues, you can reproduce them using the same environment as
the one used by the CI thanks to a docker image, e.g.:

    $ cd [kernel source code]
    $ docker run -v "${PWD}:${PWD}:rw" -w "${PWD}" --privileged --rm -it \
        --pull always mptcp/mptcp-upstream-virtme-docker:latest \
        auto-debug

For more details:

    https://github.com/multipath-tcp/mptcp-upstream-virtme-docker


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)

Re: mptcp: process pending subflow error on close: Tests Results

[MPTCP CI]

Hi Paolo,

Thank you for your modifications, that's great!

Our CI did some validations and here is its report:

- KVM Validation: normal (except selftest_mptcp_join):
  - Success! ✅:
  - Task: https://cirrus-ci.com/task/6687372218204160
  - Summary: https://api.cirrus-ci.com/v1/artifact/task/6687372218204160/summary/summary.txt

- KVM Validation: debug (only selftest_mptcp_join):
  - Success! ✅:
  - Task: https://cirrus-ci.com/task/5104075474206720
  - Summary: https://api.cirrus-ci.com/v1/artifact/task/5104075474206720/summary/summary.txt

- KVM Validation: debug (except selftest_mptcp_join):
  - Success! ✅:
  - Task: https://cirrus-ci.com/task/5667025427628032
  - Summary: https://api.cirrus-ci.com/v1/artifact/task/5667025427628032/summary/summary.txt

- KVM Validation: normal (only selftest_mptcp_join):
  - Success! ✅:
  - Task: https://cirrus-ci.com/task/4541125520785408
  - Summary: https://api.cirrus-ci.com/v1/artifact/task/4541125520785408/summary/summary.txt

Initiator: Patchew Applier
Commits: https://github.com/multipath-tcp/mptcp_net-next/commits/fe4acd2e87af


If there are some issues, you can reproduce them using the same environment as
the one used by the CI thanks to a docker image, e.g.:

    $ cd [kernel source code]
    $ docker run -v "${PWD}:${PWD}:rw" -w "${PWD}" --privileged --rm -it \
        --pull always mptcp/mptcp-upstream-virtme-docker:latest \
        auto-debug

For more details:

    https://github.com/multipath-tcp/mptcp-upstream-virtme-docker


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)

Re: [PATCH v2 mptcp-net 0/2] mptcp: fix missing close transition

[Mat Martineau]

On Wed, 23 Aug 2023, Paolo Abeni wrote:

> This is an attempt to address the 2nd issue reported in:
>
> https://github.com/multipath-tcp/mptcp_net-next/issues/427
>
> See the individual patch changelog for the details. The cover letter
> is here mainly to trigger the CI.
>
> v1 -> v2:
> - fix compile warning reported by the CI
>
> Paolo Abeni (2):
>  mptcp: move __mptcp_error_report in protocol.c
>  mptcp: process pending subflow error on close
>
> net/mptcp/protocol.c | 41 +++++++++++++++++++++++++++++++++++++++++
> net/mptcp/subflow.c  | 36 ------------------------------------
> 2 files changed, 41 insertions(+), 36 deletions(-)

Thanks for the v2, series looks good:

Reviewed-by: Mat Martineau <martineau@kernel.org>