linux-kernel - [PATCH net-next 09/10] mptcp: sched: reduce size for unused data

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Message-Id: <20250221-net-next-mptcp-pm-misc-cleanup-3-v1-9-2b70ab1cee79@kernel.org>
Date: Fri, 21 Feb 2025 16:44:02 +0100
From: "Matthieu Baerts (NGI0)" <matttbe@...nel.org>
To: mptcp@...ts.linux.dev, Mat Martineau <martineau@...nel.org>, 
 Geliang Tang <geliang@...nel.org>, "David S. Miller" <davem@...emloft.net>, 
 Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, 
 Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org, 
 "Matthieu Baerts (NGI0)" <matttbe@...nel.org>
Subject: [PATCH net-next 09/10] mptcp: sched: reduce size for unused data

Thanks for the previous commit ("mptcp: sched: split get_subflow
interface into two"), the mptcp_sched_data structure is now currently
unused.

This structure has been added to allow future extensions that are not
ready yet. At the end, this structure will not even be used at all when
mptcp_subflow bpf_iter will be supported [1].

Here is a first step to save 64 bytes on the stack for each scheduling
operation. The structure is not removed yet not to break the WIP work on
these extensions, but will be done when [1] will be ready and applied.

Link: https://lore.kernel.org/6645ad6e-8874-44c5-8730-854c30673218@linux.dev [1]
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@...nel.org>
---
 net/mptcp/sched.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/net/mptcp/sched.c b/net/mptcp/sched.c
index 94dc4b3ad82f6a462961ae5195b7eba2271d8275..c16c6fbd4ba2f89a2fffcfd6b1916098d7a18cbe 100644
--- a/net/mptcp/sched.c
+++ b/net/mptcp/sched.c
@@ -157,7 +157,7 @@ void mptcp_subflow_set_scheduled(struct mptcp_subflow_context *subflow,
 int mptcp_sched_get_send(struct mptcp_sock *msk)
 {
 	struct mptcp_subflow_context *subflow;
-	struct mptcp_sched_data data;
+	struct mptcp_sched_data *data = NULL;

 	msk_owned_by_me(msk);

@@ -178,14 +178,14 @@ int mptcp_sched_get_send(struct mptcp_sock *msk)
 	}

 	if (msk->sched == &mptcp_sched_default || !msk->sched)
-		return mptcp_sched_default_get_send(msk, &data);
-	return msk->sched->get_send(msk, &data);
+		return mptcp_sched_default_get_send(msk, data);
+	return msk->sched->get_send(msk, data);
 }

 int mptcp_sched_get_retrans(struct mptcp_sock *msk)
 {
 	struct mptcp_subflow_context *subflow;
-	struct mptcp_sched_data data;
+	struct mptcp_sched_data *data = NULL;

 	msk_owned_by_me(msk);

@@ -199,8 +199,8 @@ int mptcp_sched_get_retrans(struct mptcp_sock *msk)
 	}

 	if (msk->sched == &mptcp_sched_default || !msk->sched)
-		return mptcp_sched_default_get_retrans(msk, &data);
+		return mptcp_sched_default_get_retrans(msk, data);
 	if (msk->sched->get_retrans)
-		return msk->sched->get_retrans(msk, &data);
-	return msk->sched->get_send(msk, &data);
+		return msk->sched->get_retrans(msk, data);
+	return msk->sched->get_send(msk, data);
 }

-- 
2.47.1