netdev - [PATCH net-next v2] net/smc: add sysctl for smc_limit

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Message-Id: <1724207797-79030-1-git-send-email-alibuda@linux.alibaba.com>
Date: Wed, 21 Aug 2024 10:36:37 +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 v2] 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, since commit 462791bbfa35 ("net/smc: add sysctl interface for SMC")
had introcuded smc_sysctl_net_init(), it is reasonable for us to
initialize limit_smc_hs in it instead of initializing it in
smc_pnet_net_int().

Signed-off-by: D. Wythe <alibuda@...ux.alibaba.com>
---
v1 -> v2:

Modified the description in the commit and removed the incorrect
spelling.

 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