[PATCH 5.17 254/772] mptcp: reset the packet scheduler on incoming MP_PRIO

[Greg Kroah-Hartman]

From: Paolo Abeni <pabeni@xxxxxxxxxx>

[ Upstream commit 43f5b111d1ff16161ce60e19aeddb999cb6f0b01 ]

When an incoming MP_PRIO option changes the backup
status of any subflow, we need to reset the packet
scheduler status, or the next send could keep using
the previously selected subflow, without taking in account
the new priorities.

Reported-by: Davide Caratti <dcaratti@xxxxxxxxxx>
Fixes: 40453a5c61f4 ("mptcp: add the incoming MP_PRIO support")
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Signed-off-by: Mat Martineau <mathew.j.martineau@xxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 net/mptcp/pm.c       | 19 +++++++++++++++----
 net/mptcp/protocol.c |  2 ++
 net/mptcp/protocol.h |  1 +
 3 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
index 1eb83cbe8aae..770c4e36c776 100644
--- a/net/mptcp/pm.c
+++ b/net/mptcp/pm.c
@@ -261,14 +261,25 @@ void mptcp_pm_rm_addr_received(struct mptcp_sock *msk,
 	spin_unlock_bh(&pm->lock);
 }
 
-void mptcp_pm_mp_prio_received(struct sock *sk, u8 bkup)
+void mptcp_pm_mp_prio_received(struct sock *ssk, u8 bkup)
 {
-	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
+	struct sock *sk = subflow->conn;
+	struct mptcp_sock *msk;
 
 	pr_debug("subflow->backup=%d, bkup=%d\n", subflow->backup, bkup);
-	subflow->backup = bkup;
+	msk = mptcp_sk(sk);
+	if (subflow->backup != bkup) {
+		subflow->backup = bkup;
+		mptcp_data_lock(sk);
+		if (!sock_owned_by_user(sk))
+			msk->last_snd = NULL;
+		else
+			__set_bit(MPTCP_RESET_SCHEDULER,  &msk->cb_flags);
+		mptcp_data_unlock(sk);
+	}
 
-	mptcp_event(MPTCP_EVENT_SUB_PRIORITY, mptcp_sk(subflow->conn), sk, GFP_ATOMIC);
+	mptcp_event(MPTCP_EVENT_SUB_PRIORITY, msk, ssk, GFP_ATOMIC);
 }
 
 void mptcp_pm_mp_fail_received(struct sock *sk, u64 fail_seq)
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 7e8083d6f033..4a50906f4d8f 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -3098,6 +3098,8 @@ static void mptcp_release_cb(struct sock *sk)
 			__mptcp_set_connected(sk);
 		if (__test_and_clear_bit(MPTCP_ERROR_REPORT, &msk->cb_flags))
 			__mptcp_error_report(sk);
+		if (__test_and_clear_bit(MPTCP_RESET_SCHEDULER, &msk->cb_flags))
+			msk->last_snd = NULL;
 	}
 
 	__mptcp_update_rmem(sk);
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 46b343a0b17e..2ae8276b82fc 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -124,6 +124,7 @@
 #define MPTCP_RETRANSMIT	4
 #define MPTCP_FLUSH_JOIN_LIST	5
 #define MPTCP_CONNECTED		6
+#define MPTCP_RESET_SCHEDULER	7
 
 static inline bool before64(__u64 seq1, __u64 seq2)
 {
-- 
2.35.1