netdev - [PATCH net-next] net/smc: add sysctl for smc_limit

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Message-Id: <1723726988-78651-1-git-send-email-alibuda@linux.alibaba.com>
Date: Thu, 15 Aug 2024 21:03:08 +0800
From: "D. Wythe" <alibuda@...ux.alibaba.com>
To: kgraul@...ux.ibm.com,
	wenjia@...ux.ibm.com,
	jaka@...ux.ibm.com,
	wintera@...ux.ibm.com,
	guwen@...ux.alibaba.com
Cc: kuba@...nel.org,
	davem@...emloft.net,
	netdev@...r.kernel.org,
	linux-s390@...r.kernel.org,
	linux-rdma@...r.kernel.org,
	tonylu@...ux.alibaba.com,
	pabeni@...hat.com,
	edumazet@...gle.com
Subject: [PATCH net-next] net/smc: add sysctl for smc_limit_hs

From: "D. Wythe" <alibuda@...ux.alibaba.com>

In commit 48b6190a0042 ("net/smc: Limit SMC visits when handshake workqueue congested"),
we introduce a mechanism to put constraint on SMC connections visit according to
the pressure of SMC handshake process.

At that time, we believed that controlling the feature through netlink was sufficient,
However, most people have realized now that netlink is not convenient in
container scenarios, and sysctl is a more suitable approach.

In addition, it is not reasonable for us to initialize limit_smc_hs in
smc_pnet_net_init, we made a mistable before. It should be initialized
in smc_sysctl_net_init(), just like other systcl.

Signed-off-by: D. Wythe <alibuda@...ux.alibaba.com>
---
 net/smc/smc_pnet.c   |  3 ---
 net/smc/smc_sysctl.c | 11 +++++++++++
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/net/smc/smc_pnet.c b/net/smc/smc_pnet.c
index 2adb92b..1dd3623 100644
--- a/net/smc/smc_pnet.c
+++ b/net/smc/smc_pnet.c
@@ -887,9 +887,6 @@ int smc_pnet_net_init(struct net *net)
 
 	smc_pnet_create_pnetids_list(net);
 
-	/* disable handshake limitation by default */
-	net->smc.limit_smc_hs = 0;
-
 	return 0;
 }
 
diff --git a/net/smc/smc_sysctl.c b/net/smc/smc_sysctl.c
index 13f2bc0..2fab645 100644
--- a/net/smc/smc_sysctl.c
+++ b/net/smc/smc_sysctl.c
@@ -90,6 +90,15 @@
 		.extra1		= &conns_per_lgr_min,
 		.extra2		= &conns_per_lgr_max,
 	},
+	{
+		.procname	= "limit_smc_hs",
+		.data		= &init_net.smc.limit_smc_hs,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
+	},
 };
 
 int __net_init smc_sysctl_net_init(struct net *net)
@@ -121,6 +130,8 @@ int __net_init smc_sysctl_net_init(struct net *net)
 	WRITE_ONCE(net->smc.sysctl_rmem, net_smc_rmem_init);
 	net->smc.sysctl_max_links_per_lgr = SMC_LINKS_PER_LGR_MAX_PREFER;
 	net->smc.sysctl_max_conns_per_lgr = SMC_CONN_PER_LGR_PREFER;
+	/* disable handshake limitation by default */
+	net->smc.limit_smc_hs = 0;
 
 	return 0;
 
-- 
1.8.3.1