[PATCH v3 4/5] sysctl: mq: use typed fields for IPC namespace sysctls

[Alexey Gladkov <legion@kernel.org>]

Convert mq_sysctls. The table can now share one static array across ipc
namespaces instead of allocating and rewriting a ctl_table copy for each
registration.

Signed-off-by: Alexey Gladkov <legion@kernel.org>
---
 ipc/mq_sysctl.c | 104 ++++++++++++++++++++----------------------------
 1 file changed, 43 insertions(+), 61 deletions(-)

diff --git a/ipc/mq_sysctl.c b/ipc/mq_sysctl.c
index 0dd12e1c9f53..e237247d330b 100644
--- a/ipc/mq_sysctl.c
+++ b/ipc/mq_sysctl.c
@@ -14,55 +14,63 @@
 #include <linux/slab.h>
 #include <linux/cred.h>
 
-static int msg_max_limit_min = MIN_MSGMAX;
-static int msg_max_limit_max = HARD_MSGMAX;
+static unsigned int msg_max_limit_min = MIN_MSGMAX;
+static unsigned int msg_max_limit_max = HARD_MSGMAX;
 
-static int msg_maxsize_limit_min = MIN_MSGSIZEMAX;
-static int msg_maxsize_limit_max = HARD_MSGSIZEMAX;
+static unsigned int msg_maxsize_limit_min = MIN_MSGSIZEMAX;
+static unsigned int msg_maxsize_limit_max = HARD_MSGSIZEMAX;
 
-static const struct ctl_table mq_sysctls[] = {
+static const struct sysctl_field mq_sysctls[] = {
 	{
 		.procname	= "queues_max",
-		.data		= &init_ipc_ns.mq_queues_max,
-		.maxlen		= sizeof(int),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec,
+		.type		= SYSCTL_FIELD_UINT,
+		.data_offset	= SYSCTL_FIELD_UINT_OFFSET(struct ipc_namespace,
+							   mq_queues_max),
 	},
 	{
 		.procname	= "msg_max",
-		.data		= &init_ipc_ns.mq_msg_max,
-		.maxlen		= sizeof(int),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &msg_max_limit_min,
-		.extra2		= &msg_max_limit_max,
+		.type		= SYSCTL_FIELD_UINT,
+		.data_offset	= SYSCTL_FIELD_UINT_OFFSET(struct ipc_namespace,
+							   mq_msg_max),
+		.uint_limits = {
+			.min	= &msg_max_limit_min,
+			.max	= &msg_max_limit_max,
+		},
 	},
 	{
 		.procname	= "msgsize_max",
-		.data		= &init_ipc_ns.mq_msgsize_max,
-		.maxlen		= sizeof(int),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &msg_maxsize_limit_min,
-		.extra2		= &msg_maxsize_limit_max,
+		.type		= SYSCTL_FIELD_UINT,
+		.data_offset	= SYSCTL_FIELD_UINT_OFFSET(struct ipc_namespace,
+							   mq_msgsize_max),
+		.uint_limits = {
+			.min	= &msg_maxsize_limit_min,
+			.max	= &msg_maxsize_limit_max,
+		},
 	},
 	{
 		.procname	= "msg_default",
-		.data		= &init_ipc_ns.mq_msg_default,
-		.maxlen		= sizeof(int),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &msg_max_limit_min,
-		.extra2		= &msg_max_limit_max,
+		.type		= SYSCTL_FIELD_UINT,
+		.data_offset	= SYSCTL_FIELD_UINT_OFFSET(struct ipc_namespace,
+							   mq_msg_default),
+		.uint_limits = {
+			.min	= &msg_max_limit_min,
+			.max	= &msg_max_limit_max,
+		},
 	},
 	{
 		.procname	= "msgsize_default",
-		.data		= &init_ipc_ns.mq_msgsize_default,
-		.maxlen		= sizeof(int),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &msg_maxsize_limit_min,
-		.extra2		= &msg_maxsize_limit_max,
+		.type		= SYSCTL_FIELD_UINT,
+		.data_offset	= SYSCTL_FIELD_UINT_OFFSET(struct ipc_namespace,
+							   mq_msgsize_default),
+		.uint_limits = {
+			.min	= &msg_maxsize_limit_min,
+			.max	= &msg_maxsize_limit_max,
+		},
 	},
 };
 
@@ -116,39 +124,17 @@ static struct ctl_table_root set_root = {
 
 bool setup_mq_sysctls(struct ipc_namespace *ns)
 {
-	struct ctl_table *tbl;
+	struct sysctl_context ctx = {
+		.type = SYSCTL_CONTEXT_IPC_NS,
+		.object_size = sizeof(*ns),
+		.ns.ipc_ns = ns,
+	};
 
 	setup_sysctl_set(&ns->mq_set, &set_root, set_is_seen);
 
-	tbl = kmemdup(mq_sysctls, sizeof(mq_sysctls), GFP_KERNEL);
-	if (tbl) {
-		int i;
-
-		for (i = 0; i < ARRAY_SIZE(mq_sysctls); i++) {
-			if (tbl[i].data == &init_ipc_ns.mq_queues_max)
-				tbl[i].data = &ns->mq_queues_max;
-
-			else if (tbl[i].data == &init_ipc_ns.mq_msg_max)
-				tbl[i].data = &ns->mq_msg_max;
-
-			else if (tbl[i].data == &init_ipc_ns.mq_msgsize_max)
-				tbl[i].data = &ns->mq_msgsize_max;
-
-			else if (tbl[i].data == &init_ipc_ns.mq_msg_default)
-				tbl[i].data = &ns->mq_msg_default;
-
-			else if (tbl[i].data == &init_ipc_ns.mq_msgsize_default)
-				tbl[i].data = &ns->mq_msgsize_default;
-			else
-				tbl[i].data = NULL;
-		}
-
-		ns->mq_sysctls = __register_sysctl_table(&ns->mq_set,
-							 "fs/mqueue", tbl,
-							 ARRAY_SIZE(mq_sysctls));
-	}
+	ns->mq_sysctls = register_sysctl_fields(&ns->mq_set, "fs/mqueue",
+						mq_sysctls, &ctx);
 	if (!ns->mq_sysctls) {
-		kfree(tbl);
 		retire_sysctl_set(&ns->mq_set);
 		return false;
 	}
@@ -158,10 +144,6 @@ bool setup_mq_sysctls(struct ipc_namespace *ns)
 
 void retire_mq_sysctls(struct ipc_namespace *ns)
 {
-	const struct ctl_table *tbl;
-
-	tbl = ns->mq_sysctls->ctl_table_arg;
 	unregister_sysctl_table(ns->mq_sysctls);
 	retire_sysctl_set(&ns->mq_set);
-	kfree(tbl);
 }
-- 
2.55.0