Merge branch 'mptcp-fixes-and-maintainer-email-update-for-v6-6'

Mat Martineau says:

====================
mptcp: Fixes and maintainer email update for v6.6

Patch 1 addresses a race condition in MPTCP "delegated actions"
infrastructure. Affects v5.19 and later.

Patch 2 removes an unnecessary restriction that did not allow additional
outgoing subflows using the local address of the initial MPTCP subflow.
v5.16 and later.

Patch 3 updates Matthieu's email address.
====================

Link: https://lore.kernel.org/r/20231004-send-net-20231004-v1-0-28de4ac663ae@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 12 insertions, 23 deletions

diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index ed61d6850cce..3612545fa62e 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -444,9 +444,11 @@ struct mptcp_delegated_action {
 
 DECLARE_PER_CPU(struct mptcp_delegated_action, mptcp_delegated_actions);
 
-#define MPTCP_DELEGATE_SEND		0
-#define MPTCP_DELEGATE_ACK		1
+#define MPTCP_DELEGATE_SCHEDULED	0
+#define MPTCP_DELEGATE_SEND		1
+#define MPTCP_DELEGATE_ACK		2
 
+#define MPTCP_DELEGATE_ACTIONS_MASK	(~BIT(MPTCP_DELEGATE_SCHEDULED))
 /* MPTCP subflow context */
 struct mptcp_subflow_context {
 	struct	list_head node;/* conn_list of subflows */
@@ -564,23 +566,24 @@ mptcp_subflow_get_mapped_dsn(const struct mptcp_subflow_context *subflow)
 	return subflow->map_seq + mptcp_subflow_get_map_offset(subflow);
 }
 
-void mptcp_subflow_process_delegated(struct sock *ssk);
+void mptcp_subflow_process_delegated(struct sock *ssk, long actions);
 
 static inline void mptcp_subflow_delegate(struct mptcp_subflow_context *subflow, int action)
 {
+	long old, set_bits = BIT(MPTCP_DELEGATE_SCHEDULED) | BIT(action);
 	struct mptcp_delegated_action *delegated;
 	bool schedule;
 
 	/* the caller held the subflow bh socket lock */
 	lockdep_assert_in_softirq();
 
-	/* The implied barrier pairs with mptcp_subflow_delegated_done(), and
-	 * ensures the below list check sees list updates done prior to status
-	 * bit changes
+	/* The implied barrier pairs with tcp_release_cb_override()
+	 * mptcp_napi_poll(), and ensures the below list check sees list
+	 * updates done prior to delegated status bits changes
 	 */
-	if (!test_and_set_bit(action, &subflow->delegated_status)) {
-		/* still on delegated list from previous scheduling */
-		if (!list_empty(&subflow->delegated_node))
+	old = set_mask_bits(&subflow->delegated_status, 0, set_bits);
+	if (!(old & BIT(MPTCP_DELEGATE_SCHEDULED))) {
+		if (WARN_ON_ONCE(!list_empty(&subflow->delegated_node)))
 			return;
 
 		delegated = this_cpu_ptr(&mptcp_delegated_actions);
@@ -605,20 +608,6 @@ mptcp_subflow_delegated_next(struct mptcp_delegated_action *delegated)
 	return ret;
 }
 
-static inline bool mptcp_subflow_has_delegated_action(const struct mptcp_subflow_context *subflow)
-{
-	return !!READ_ONCE(subflow->delegated_status);
-}
-
-static inline void mptcp_subflow_delegated_done(struct mptcp_subflow_context *subflow, int action)
-{
-	/* pairs with mptcp_subflow_delegate, ensures delegate_node is updated before
-	 * touching the status bit
-	 */
-	smp_wmb();
-	clear_bit(action, &subflow->delegated_status);
-}
-
 int mptcp_is_enabled(const struct net *net);
 unsigned int mptcp_get_add_addr_timeout(const struct net *net);
 int mptcp_is_checksum_enabled(const struct net *net);