From caf02cd7505b783c85026422fa56a35b773ba494 Mon Sep 17 00:00:00 2001
From: Geliang Tang <geliangtang@gmail.com>
Date: Tue, 4 May 2021 23:42:08 +0200
Subject: [PATCH] mptcp: add a new sysctl checksum_enabled

This patch added a new sysctl, named checksum_enabled, to control
whether DSS checksum can be enabled.

Acked-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Geliang Tang <geliangtang@gmail.com>
---
 Documentation/networking/mptcp-sysctl.rst |  8 ++++++++
 net/mptcp/ctrl.c                          | 14 ++++++++++++++
 net/mptcp/protocol.h                      |  2 +-
 3 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/Documentation/networking/mptcp-sysctl.rst b/Documentation/networking/mptcp-sysctl.rst
index 3b352e5f6300c..901fa3e4650f2 100644
--- a/Documentation/networking/mptcp-sysctl.rst
+++ b/Documentation/networking/mptcp-sysctl.rst
@@ -24,3 +24,11 @@ add_addr_timeout - INTEGER (seconds)
 	sysctl.
 
 	Default: 120
+
+checksum_enabled - INTEGER
+	Control whether DSS checksum can be enabled.
+
+	DSS checksum can be enabled if the value is nonzero. This is a
+	per-namespace sysctl.
+
+	Default: 0
diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c
index 1ec4d36a39f05..014752c481d00 100644
--- a/net/mptcp/ctrl.c
+++ b/net/mptcp/ctrl.c
@@ -23,6 +23,7 @@ struct mptcp_pernet {
 
 	u8 mptcp_enabled;
 	unsigned int add_addr_timeout;
+	int checksum_enabled;
 };
 
 static struct mptcp_pernet *mptcp_get_pernet(struct net *net)
@@ -44,9 +45,15 @@ static void mptcp_pernet_set_defaults(struct mptcp_pernet *pernet)
 {
 	pernet->mptcp_enabled = 1;
 	pernet->add_addr_timeout = TCP_RTO_MAX;
+	pernet->checksum_enabled = 0;
 }
 
 #ifdef CONFIG_SYSCTL
+int mptcp_is_checksum_enabled(struct net *net)
+{
+	return mptcp_get_pernet(net)->checksum_enabled;
+}
+
 static struct ctl_table mptcp_sysctl_table[] = {
 	{
 		.procname = "enabled",
@@ -65,6 +72,12 @@ static struct ctl_table mptcp_sysctl_table[] = {
 		.mode = 0644,
 		.proc_handler = proc_dointvec_jiffies,
 	},
+	{
+		.procname = "checksum_enabled",
+		.maxlen = sizeof(int),
+		.mode = 0644,
+		.proc_handler = proc_dointvec,
+	},
 	{}
 };
 
@@ -82,6 +95,7 @@ static int mptcp_pernet_new_table(struct net *net, struct mptcp_pernet *pernet)
 
 	table[0].data = &pernet->mptcp_enabled;
 	table[1].data = &pernet->add_addr_timeout;
+	table[2].data = &pernet->checksum_enabled;
 
 	hdr = register_net_sysctl(net, MPTCP_SYSCTL_PATH, table);
 	if (!hdr)
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 39ba2efc60e93..98c735f237b46 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -541,7 +541,7 @@ static inline void mptcp_subflow_delegated_done(struct mptcp_subflow_context *su
 
 int mptcp_is_enabled(struct net *net);
 unsigned int mptcp_get_add_addr_timeout(struct net *net);
-static inline int mptcp_is_checksum_enabled(struct net *net) { return false; }
+int mptcp_is_checksum_enabled(struct net *net);
 void mptcp_subflow_fully_established(struct mptcp_subflow_context *subflow,
 				     struct mptcp_options_received *mp_opt);
 bool mptcp_subflow_data_available(struct sock *sk);