From af37d2080c2a8598a54945fc6df60e266c9dc43b Mon Sep 17 00:00:00 2001
From: Paolo Abeni <pabeni@redhat.com>
Date: Thu, 30 Jun 2022 15:17:56 -0700
Subject: [PATCH] mptcp: refine memory scheduling

commit 69d93daec026cdda98e29e8edb12534bfa5b1a9b upstream.

Similar to commit 7c80b038d23e ("net: fix sk_wmem_schedule() and
sk_rmem_schedule() errors"), let the MPTCP receive path schedule
exactly the required amount of memory.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/mptcp/protocol.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 7e1518bb6115..8ffb8aabd324 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -323,9 +323,10 @@ static bool mptcp_rmem_schedule(struct sock *sk, struct sock *ssk, int size)
 	struct mptcp_sock *msk = mptcp_sk(sk);
 	int amt, amount;
 
-	if (size < msk->rmem_fwd_alloc)
+	if (size <= msk->rmem_fwd_alloc)
 		return true;
 
+	size -= msk->rmem_fwd_alloc;
 	amt = sk_mem_pages(size);
 	amount = amt << SK_MEM_QUANTUM_SHIFT;
 	msk->rmem_fwd_alloc += amount;