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From: =?utf-8?q?Thomas_Wei=C3=9Fschuh?= <linux@weissschuh.net>
Date: Fri, 22 Mar 2024 21:34:36 +0100
Subject: [PATCH] sysctl: treewide: constify ctl_table_header::ctl_table_arg
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Message-Id: <20240322-sysctl-const-table-arg-v1-1-88436d34961b@weissschuh.net>
To: Eric Dumazet <edumazet@google.com>, 
 Luis Chamberlain <mcgrof@kernel.org>, 
 Joel Granados <j.granados@samsung.com>
Cc: linux-kernel@vger.kernel.org, 
 =?utf-8?q?Thomas_Wei=C3=9Fschuh?= <linux@weissschuh.net>

To be able to constify instances of struct ctl_tables it is necessary to
remove ways through which non-const versions are exposed from the
sysctl core.
One of these is the ctl_table_arg member of struct ctl_table_header.

Constify this reference as a prerequisite for the full constification of
struct ctl_table instances.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---
This patch is only sent to LKML and the sysctl maintainers to avoid
spamming lots of maintainers for trivial changes.

It is based upon the branch sysctl/constfy.

It was implemented by manually searching for "ctl_table_arg"
throughout the tree and inspecing each found site.

If somebody comes up with a cocciscript for this, I'll be happy to use
that.
---
 drivers/net/vrf.c                       | 2 +-
 include/linux/sysctl.h                  | 2 +-
 ipc/ipc_sysctl.c                        | 2 +-
 ipc/mq_sysctl.c                         | 2 +-
 kernel/ucount.c                         | 2 +-
 net/ax25/sysctl_net_ax25.c              | 2 +-
 net/bridge/br_netfilter_hooks.c         | 2 +-
 net/core/sysctl_net_core.c              | 2 +-
 net/ieee802154/6lowpan/reassembly.c     | 2 +-
 net/ipv4/devinet.c                      | 2 +-
 net/ipv4/ip_fragment.c                  | 2 +-
 net/ipv4/route.c                        | 2 +-
 net/ipv4/sysctl_net_ipv4.c              | 2 +-
 net/ipv4/xfrm4_policy.c                 | 2 +-
 net/ipv6/addrconf.c                     | 2 +-
 net/ipv6/netfilter/nf_conntrack_reasm.c | 2 +-
 net/ipv6/reassembly.c                   | 2 +-
 net/ipv6/sysctl_net_ipv6.c              | 6 +++---
 net/ipv6/xfrm6_policy.c                 | 2 +-
 net/mpls/af_mpls.c                      | 4 ++--
 net/mptcp/ctrl.c                        | 2 +-
 net/netfilter/nf_conntrack_standalone.c | 2 +-
 net/netfilter/nf_log.c                  | 2 +-
 net/sctp/sysctl.c                       | 2 +-
 net/smc/smc_sysctl.c                    | 2 +-
 net/unix/sysctl_net_unix.c              | 2 +-
 net/xfrm/xfrm_sysctl.c                  | 2 +-
 27 files changed, 30 insertions(+), 30 deletions(-)

diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c
index bb95ce43cd97..66f8542f3b18 100644
--- a/drivers/net/vrf.c
+++ b/drivers/net/vrf.c
@@ -1971,7 +1971,7 @@ static int vrf_netns_init_sysctl(struct net *net, struct netns_vrf *nn_vrf)
 static void vrf_netns_exit_sysctl(struct net *net)
 {
 	struct netns_vrf *nn_vrf = net_generic(net, vrf_net_id);
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	table = nn_vrf->ctl_hdr->ctl_table_arg;
 	unregister_net_sysctl_table(nn_vrf->ctl_hdr);
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index f9214de0490c..1d277be47302 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -182,7 +182,7 @@ struct ctl_table_header {
 		struct rcu_head rcu;
 	};
 	struct completion *unregistering;
-	struct ctl_table *ctl_table_arg;
+	const struct ctl_table *ctl_table_arg;
 	struct ctl_table_root *root;
 	struct ctl_table_set *set;
 	struct ctl_dir *parent;
diff --git a/ipc/ipc_sysctl.c b/ipc/ipc_sysctl.c
index 19b2a67aef40..113452038303 100644
--- a/ipc/ipc_sysctl.c
+++ b/ipc/ipc_sysctl.c
@@ -305,7 +305,7 @@ bool setup_ipc_sysctls(struct ipc_namespace *ns)
 
 void retire_ipc_sysctls(struct ipc_namespace *ns)
 {
-	struct ctl_table *tbl;
+	const struct ctl_table *tbl;
 
 	tbl = ns->ipc_sysctls->ctl_table_arg;
 	unregister_sysctl_table(ns->ipc_sysctls);
diff --git a/ipc/mq_sysctl.c b/ipc/mq_sysctl.c
index 43c0825da9e8..068e7d5aa42b 100644
--- a/ipc/mq_sysctl.c
+++ b/ipc/mq_sysctl.c
@@ -159,7 +159,7 @@ bool setup_mq_sysctls(struct ipc_namespace *ns)
 
 void retire_mq_sysctls(struct ipc_namespace *ns)
 {
-	struct ctl_table *tbl;
+	const struct ctl_table *tbl;
 
 	tbl = ns->mq_sysctls->ctl_table_arg;
 	unregister_sysctl_table(ns->mq_sysctls);
diff --git a/kernel/ucount.c b/kernel/ucount.c
index 90300840256b..366a2c1971f5 100644
--- a/kernel/ucount.c
+++ b/kernel/ucount.c
@@ -119,7 +119,7 @@ bool setup_userns_sysctls(struct user_namespace *ns)
 void retire_userns_sysctls(struct user_namespace *ns)
 {
 #ifdef CONFIG_SYSCTL
-	struct ctl_table *tbl;
+	const struct ctl_table *tbl;
 
 	tbl = ns->sysctls->ctl_table_arg;
 	unregister_sysctl_table(ns->sysctls);
diff --git a/net/ax25/sysctl_net_ax25.c b/net/ax25/sysctl_net_ax25.c
index db66e11e7fe8..e0128dc9def3 100644
--- a/net/ax25/sysctl_net_ax25.c
+++ b/net/ax25/sysctl_net_ax25.c
@@ -171,7 +171,7 @@ int ax25_register_dev_sysctl(ax25_dev *ax25_dev)
 void ax25_unregister_dev_sysctl(ax25_dev *ax25_dev)
 {
 	struct ctl_table_header *header = ax25_dev->sysheader;
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	if (header) {
 		ax25_dev->sysheader = NULL;
diff --git a/net/bridge/br_netfilter_hooks.c b/net/bridge/br_netfilter_hooks.c
index 35e10c5a766d..a09118c56c7d 100644
--- a/net/bridge/br_netfilter_hooks.c
+++ b/net/bridge/br_netfilter_hooks.c
@@ -1268,7 +1268,7 @@ static int br_netfilter_sysctl_init_net(struct net *net)
 static void br_netfilter_sysctl_exit_net(struct net *net,
 					 struct brnf_net *brnet)
 {
-	struct ctl_table *table = brnet->ctl_hdr->ctl_table_arg;
+	const struct ctl_table *table = brnet->ctl_hdr->ctl_table_arg;
 
 	unregister_net_sysctl_table(brnet->ctl_hdr);
 	if (!net_eq(net, &init_net))
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index 6973dda3abda..903ab4a51c17 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -743,7 +743,7 @@ static __net_init int sysctl_core_net_init(struct net *net)
 
 static __net_exit void sysctl_core_net_exit(struct net *net)
 {
-	struct ctl_table *tbl;
+	const struct ctl_table *tbl;
 
 	tbl = net->core.sysctl_hdr->ctl_table_arg;
 	unregister_net_sysctl_table(net->core.sysctl_hdr);
diff --git a/net/ieee802154/6lowpan/reassembly.c b/net/ieee802154/6lowpan/reassembly.c
index 6dd960ec558c..2a983cf450da 100644
--- a/net/ieee802154/6lowpan/reassembly.c
+++ b/net/ieee802154/6lowpan/reassembly.c
@@ -399,7 +399,7 @@ static int __net_init lowpan_frags_ns_sysctl_register(struct net *net)
 
 static void __net_exit lowpan_frags_ns_sysctl_unregister(struct net *net)
 {
-	struct ctl_table *table;
+	const struct ctl_table *table;
 	struct netns_ieee802154_lowpan *ieee802154_lowpan =
 		net_ieee802154_lowpan(net);
 
diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 7a437f0d4190..7592f242336b 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -2749,7 +2749,7 @@ static __net_init int devinet_init_net(struct net *net)
 static __net_exit void devinet_exit_net(struct net *net)
 {
 #ifdef CONFIG_SYSCTL
-	struct ctl_table *tbl;
+	const struct ctl_table *tbl;
 
 	tbl = net->ipv4.forw_hdr->ctl_table_arg;
 	unregister_net_sysctl_table(net->ipv4.forw_hdr);
diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index a4941f53b523..6b9285fd6f06 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -632,7 +632,7 @@ static int __net_init ip4_frags_ns_ctl_register(struct net *net)
 
 static void __net_exit ip4_frags_ns_ctl_unregister(struct net *net)
 {
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	table = net->ipv4.frags_hdr->ctl_table_arg;
 	unregister_net_sysctl_table(net->ipv4.frags_hdr);
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index c8f76f56dc16..af30b5942ba4 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -3590,7 +3590,7 @@ static __net_init int sysctl_route_net_init(struct net *net)
 
 static __net_exit void sysctl_route_net_exit(struct net *net)
 {
-	struct ctl_table *tbl;
+	const struct ctl_table *tbl;
 
 	tbl = net->ipv4.route_hdr->ctl_table_arg;
 	unregister_net_sysctl_table(net->ipv4.route_hdr);
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 7e4f16a7dcc1..ce5d19978a26 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -1554,7 +1554,7 @@ static __net_init int ipv4_sysctl_init_net(struct net *net)
 
 static __net_exit void ipv4_sysctl_exit_net(struct net *net)
 {
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	kfree(net->ipv4.sysctl_local_reserved_ports);
 	table = net->ipv4.ipv4_hdr->ctl_table_arg;
diff --git a/net/ipv4/xfrm4_policy.c b/net/ipv4/xfrm4_policy.c
index c33bca2c3841..1dda59e0aeab 100644
--- a/net/ipv4/xfrm4_policy.c
+++ b/net/ipv4/xfrm4_policy.c
@@ -186,7 +186,7 @@ static __net_init int xfrm4_net_sysctl_init(struct net *net)
 
 static __net_exit void xfrm4_net_sysctl_exit(struct net *net)
 {
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	if (!net->ipv4.xfrm4_hdr)
 		return;
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 247bd4d8ee45..9c34a351f115 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -7235,7 +7235,7 @@ static int __addrconf_sysctl_register(struct net *net, char *dev_name,
 static void __addrconf_sysctl_unregister(struct net *net,
 					 struct ipv6_devconf *p, int ifindex)
 {
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	if (!p->sysctl_header)
 		return;
diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c
index 1a51a44571c3..98809f846229 100644
--- a/net/ipv6/netfilter/nf_conntrack_reasm.c
+++ b/net/ipv6/netfilter/nf_conntrack_reasm.c
@@ -105,7 +105,7 @@ static int nf_ct_frag6_sysctl_register(struct net *net)
 static void __net_exit nf_ct_frags6_sysctl_unregister(struct net *net)
 {
 	struct nft_ct_frag6_pernet *nf_frag = nf_frag_pernet(net);
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	table = nf_frag->nf_frag_frags_hdr->ctl_table_arg;
 	unregister_net_sysctl_table(nf_frag->nf_frag_frags_hdr);
diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
index acb4f119e11f..ee95cdcc8747 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -487,7 +487,7 @@ static int __net_init ip6_frags_ns_sysctl_register(struct net *net)
 
 static void __net_exit ip6_frags_ns_sysctl_unregister(struct net *net)
 {
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	table = net->ipv6.sysctl.frags_hdr->ctl_table_arg;
 	unregister_net_sysctl_table(net->ipv6.sysctl.frags_hdr);
diff --git a/net/ipv6/sysctl_net_ipv6.c b/net/ipv6/sysctl_net_ipv6.c
index 888676163e90..75de55f907b0 100644
--- a/net/ipv6/sysctl_net_ipv6.c
+++ b/net/ipv6/sysctl_net_ipv6.c
@@ -313,9 +313,9 @@ static int __net_init ipv6_sysctl_net_init(struct net *net)
 
 static void __net_exit ipv6_sysctl_net_exit(struct net *net)
 {
-	struct ctl_table *ipv6_table;
-	struct ctl_table *ipv6_route_table;
-	struct ctl_table *ipv6_icmp_table;
+	const struct ctl_table *ipv6_table;
+	const struct ctl_table *ipv6_route_table;
+	const struct ctl_table *ipv6_icmp_table;
 
 	ipv6_table = net->ipv6.sysctl.hdr->ctl_table_arg;
 	ipv6_route_table = net->ipv6.sysctl.route_hdr->ctl_table_arg;
diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c
index 42fb6996b077..4891012b692f 100644
--- a/net/ipv6/xfrm6_policy.c
+++ b/net/ipv6/xfrm6_policy.c
@@ -218,7 +218,7 @@ static int __net_init xfrm6_net_sysctl_init(struct net *net)
 
 static void __net_exit xfrm6_net_sysctl_exit(struct net *net)
 {
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	if (!net->ipv6.sysctl.xfrm6_hdr)
 		return;
diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
index 6dab883a08dd..40b4dd4dc1b9 100644
--- a/net/mpls/af_mpls.c
+++ b/net/mpls/af_mpls.c
@@ -1438,7 +1438,7 @@ static void mpls_dev_sysctl_unregister(struct net_device *dev,
 				       struct mpls_dev *mdev)
 {
 	struct net *net = dev_net(dev);
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	if (!mdev->sysctl)
 		return;
@@ -2705,8 +2705,8 @@ static int mpls_net_init(struct net *net)
 static void mpls_net_exit(struct net *net)
 {
 	struct mpls_route __rcu **platform_label;
+	const struct ctl_table *table;
 	size_t platform_labels;
-	struct ctl_table *table;
 	unsigned int index;
 
 	table = net->mpls.ctl->ctl_table_arg;
diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c
index 13fe0748dde8..8d661156ab8c 100644
--- a/net/mptcp/ctrl.c
+++ b/net/mptcp/ctrl.c
@@ -198,7 +198,7 @@ static int mptcp_pernet_new_table(struct net *net, struct mptcp_pernet *pernet)
 
 static void mptcp_pernet_del_table(struct mptcp_pernet *pernet)
 {
-	struct ctl_table *table = pernet->ctl_table_hdr->ctl_table_arg;
+	const struct ctl_table *table = pernet->ctl_table_hdr->ctl_table_arg;
 
 	unregister_net_sysctl_table(pernet->ctl_table_hdr);
 
diff --git a/net/netfilter/nf_conntrack_standalone.c b/net/netfilter/nf_conntrack_standalone.c
index 0ee98ce5b816..bb9dea676ec1 100644
--- a/net/netfilter/nf_conntrack_standalone.c
+++ b/net/netfilter/nf_conntrack_standalone.c
@@ -1122,7 +1122,7 @@ static int nf_conntrack_standalone_init_sysctl(struct net *net)
 static void nf_conntrack_standalone_fini_sysctl(struct net *net)
 {
 	struct nf_conntrack_net *cnet = nf_ct_pernet(net);
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	table = cnet->sysctl_header->ctl_table_arg;
 	unregister_net_sysctl_table(cnet->sysctl_header);
diff --git a/net/netfilter/nf_log.c b/net/netfilter/nf_log.c
index 370f8231385c..efedd2f13ac7 100644
--- a/net/netfilter/nf_log.c
+++ b/net/netfilter/nf_log.c
@@ -514,7 +514,7 @@ static int netfilter_log_sysctl_init(struct net *net)
 
 static void netfilter_log_sysctl_exit(struct net *net)
 {
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	table = net->nf.nf_log_dir_header->ctl_table_arg;
 	unregister_net_sysctl_table(net->nf.nf_log_dir_header);
diff --git a/net/sctp/sysctl.c b/net/sctp/sysctl.c
index f65d6f92afcb..25bdf17c7262 100644
--- a/net/sctp/sysctl.c
+++ b/net/sctp/sysctl.c
@@ -624,7 +624,7 @@ int sctp_sysctl_net_register(struct net *net)
 
 void sctp_sysctl_net_unregister(struct net *net)
 {
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	table = net->sctp.sysctl_header->ctl_table_arg;
 	unregister_net_sysctl_table(net->sctp.sysctl_header);
diff --git a/net/smc/smc_sysctl.c b/net/smc/smc_sysctl.c
index a5946d1b9d60..4e8baa2e7ea4 100644
--- a/net/smc/smc_sysctl.c
+++ b/net/smc/smc_sysctl.c
@@ -133,7 +133,7 @@ int __net_init smc_sysctl_net_init(struct net *net)
 
 void __net_exit smc_sysctl_net_exit(struct net *net)
 {
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	table = net->smc.smc_hdr->ctl_table_arg;
 	unregister_net_sysctl_table(net->smc.smc_hdr);
diff --git a/net/unix/sysctl_net_unix.c b/net/unix/sysctl_net_unix.c
index 3e84b31c355a..44996af61999 100644
--- a/net/unix/sysctl_net_unix.c
+++ b/net/unix/sysctl_net_unix.c
@@ -52,7 +52,7 @@ int __net_init unix_sysctl_register(struct net *net)
 
 void unix_sysctl_unregister(struct net *net)
 {
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	table = net->unx.ctl->ctl_table_arg;
 	unregister_net_sysctl_table(net->unx.ctl);
diff --git a/net/xfrm/xfrm_sysctl.c b/net/xfrm/xfrm_sysctl.c
index 7fdeafc838a7..e972930c292b 100644
--- a/net/xfrm/xfrm_sysctl.c
+++ b/net/xfrm/xfrm_sysctl.c
@@ -76,7 +76,7 @@ int __net_init xfrm_sysctl_init(struct net *net)
 
 void __net_exit xfrm_sysctl_fini(struct net *net)
 {
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	table = net->xfrm.sysctl_hdr->ctl_table_arg;
 	unregister_net_sysctl_table(net->xfrm.sysctl_hdr);

---
base-commit: 87a288e4a89649e7f51f9c0b568dc73d9908099d
change-id: 20231226-sysctl-const-table-arg-2c828e0264dc

Best regards,
-- 
Thomas Weißschuh <linux@weissschuh.net>