[PATCH v5 1/8] net: Remove the now superfluous sentinel elements from ctl_table array

Joel Granados via B4 Relay
2024-04-26T10:47:10Z

From: Joel Granados <j.granados@samsung.com>

This commit comes at the tail end of a greater effort to remove the
empty elements at the end of the ctl_table arrays (sentinels) which
will reduce the overall build time size of the kernel and run time
memory bloat by ~64 bytes per sentinel (further information Link :
https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)

* Remove sentinel element from ctl_table structs.
* Remove the zeroing out of an array element (to make it look like a
sentinel) in neigh_sysctl_register and lowpan_frags_ns_sysctl_register
This is not longer needed and is safe after commit c899710fe7f9
("networking: Update to register_net_sysctl_sz") added the array size
to the ctl_table registration.
* Replace the for loop stop condition in sysctl_core_net_init that tests
for procname == NULL with one that depends on array size
* Removed the "-1" in mpls_net_init that adjusted for having an extra
empty element when looping over ctl_table arrays
* Use a table_size variable to keep the value of ARRAY_SIZE

Signed-off-by: Joel Granados <j.granados@samsung.com>
---
net/core/neighbour.c | 5 +----
net/core/sysctl_net_core.c | 12 +++++-------
net/dccp/sysctl.c | 2 --
net/ieee802154/6lowpan/reassembly.c | 6 +-----
net/mpls/af_mpls.c | 12 ++++++------
net/unix/sysctl_net_unix.c | 1 -
6 files changed, 13 insertions(+), 25 deletions(-)

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 552719c3bbc3..b0327402b3e6 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -3728,7 +3728,7 @@ static int neigh_proc_base_reachable_time(struct ctl_table *ctl, int write,

static struct neigh_sysctl_table {
struct ctl_table_header *sysctl_header;
- struct ctl_table neigh_vars[NEIGH_VAR_MAX + 1];
+ struct ctl_table neigh_vars[NEIGH_VAR_MAX];
} neigh_sysctl_template __read_mostly = {
.neigh_vars = {
NEIGH_SYSCTL_ZERO_INTMAX_ENTRY(MCAST_PROBES, "mcast_solicit"),
@@ -3779,7 +3779,6 @@ static struct neigh_sysctl_table {
.extra2 = SYSCTL_INT_MAX,
.proc_handler = proc_dointvec_minmax,
},
- {},
},
};

@@ -3807,8 +3806,6 @@ int neigh_sysctl_register(struct net_device *dev, struct neigh_parms *p,
if (dev) {
dev_name_source = dev->name;
/* Terminate the table early */
- memset(&t->neigh_vars[NEIGH_VAR_GC_INTERVAL], 0,
- sizeof(t->neigh_vars[NEIGH_VAR_GC_INTERVAL]));
neigh_vars_size = NEIGH_VAR_BASE_REACHABLE_TIME_MS + 1;
} else {
struct neigh_table *tbl = p->tbl;
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index 6973dda3abda..a84690b13bb9 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -660,7 +660,6 @@ static struct ctl_table net_core_table[] = {
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ZERO,
},
- { }
};

static struct ctl_table netns_core_table[] = {
@@ -697,7 +696,6 @@ static struct ctl_table netns_core_table[] = {
.extra2 = SYSCTL_ONE,
.proc_handler = proc_dou8vec_minmax,
},
- { }
};

static int __init fb_tunnels_only_for_init_net_sysctl_setup(char *str)
@@ -715,7 +713,8 @@ __setup("fb_tunnels=", fb_tunnels_only_for_init_net_sysctl_setup);

static __net_init int sysctl_core_net_init(struct net *net)
{
- struct ctl_table *tbl, *tmp;
+ size_t table_size = ARRAY_SIZE(netns_core_table);
+ struct ctl_table *tbl;

tbl = netns_core_table;
if (!net_eq(net, &init_net)) {
@@ -723,12 +722,11 @@ static __net_init int sysctl_core_net_init(struct net *net)
if (tbl == NULL)
goto err_dup;

- for (tmp = tbl; tmp->procname; tmp++)
- tmp->data += (char *)net - (char *)&init_net;
+ for (int i = 0; i < table_size; ++i)
+ (tbl + i)->data += (char *)net - (char *)&init_net;
}

- net->core.sysctl_hdr = register_net_sysctl_sz(net, "net/core", tbl,
- ARRAY_SIZE(netns_core_table));
+ net->core.sysctl_hdr = register_net_sysctl_sz(net, "net/core", tbl, table_size);
if (net->core.sysctl_hdr == NULL)
goto err_reg;

diff --git a/net/dccp/sysctl.c b/net/dccp/sysctl.c
index ee8d4f5afa72..3fc474d6e57d 100644
--- a/net/dccp/sysctl.c
+++ b/net/dccp/sysctl.c
@@ -90,8 +90,6 @@ static struct ctl_table dccp_default_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec_ms_jiffies,
},
-
- { }
};

static struct ctl_table_header *dccp_table_header;
diff --git a/net/ieee802154/6lowpan/reassembly.c b/net/ieee802154/6lowpan/reassembly.c
index 6dd960ec558c..09b18ee6df00 100644
--- a/net/ieee802154/6lowpan/reassembly.c
+++ b/net/ieee802154/6lowpan/reassembly.c
@@ -338,7 +338,6 @@ static struct ctl_table lowpan_frags_ns_ctl_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec_jiffies,
},
- { }
};

/* secret interval has been deprecated */
@@ -351,7 +350,6 @@ static struct ctl_table lowpan_frags_ctl_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec_jiffies,
},
- { }
};

static int __net_init lowpan_frags_ns_sysctl_register(struct net *net)
@@ -370,10 +368,8 @@ static int __net_init lowpan_frags_ns_sysctl_register(struct net *net)
goto err_alloc;

/* Don't export sysctls to unprivileged users */
- if (net->user_ns != &init_user_ns) {
- table[0].procname = NULL;
+ if (net->user_ns != &init_user_ns)
table_size = 0;
- }
}

table[0].data = &ieee802154_lowpan->fqdir->high_thresh;
diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
index 6dab883a08dd..ecc849678e7b 100644
--- a/net/mpls/af_mpls.c
+++ b/net/mpls/af_mpls.c
@@ -1393,13 +1393,13 @@ static const struct ctl_table mpls_dev_table[] = {
.proc_handler = mpls_conf_proc,
.data = MPLS_PERDEV_SYSCTL_OFFSET(input_enabled),
},
- { }
};

static int mpls_dev_sysctl_register(struct net_device *dev,
struct mpls_dev *mdev)
{
char path[sizeof("net/mpls/conf/") + IFNAMSIZ];
+ size_t table_size = ARRAY_SIZE(mpls_dev_table);
struct net *net = dev_net(dev);
struct ctl_table *table;
int i;
@@ -1411,7 +1411,7 @@ static int mpls_dev_sysctl_register(struct net_device *dev,
/* Table data contains only offsets relative to the base of
* the mdev at this point, so make them absolute.
*/
- for (i = 0; i < ARRAY_SIZE(mpls_dev_table); i++) {
+ for (i = 0; i < table_size; i++) {
table[i].data = (char *)mdev + (uintptr_t)table[i].data;
table[i].extra1 = mdev;
table[i].extra2 = net;
@@ -1419,8 +1419,7 @@ static int mpls_dev_sysctl_register(struct net_device *dev,

snprintf(path, sizeof(path), "net/mpls/conf/%s", dev->name);

- mdev->sysctl = register_net_sysctl_sz(net, path, table,
- ARRAY_SIZE(mpls_dev_table));
+ mdev->sysctl = register_net_sysctl_sz(net, path, table, table_size);
if (!mdev->sysctl)
goto free;

@@ -2674,6 +2673,7 @@ static const struct ctl_table mpls_table[] = {

static int mpls_net_init(struct net *net)
{
+ size_t table_size = ARRAY_SIZE(mpls_table);
struct ctl_table *table;
int i;

@@ -2689,11 +2689,11 @@ static int mpls_net_init(struct net *net)
/* Table data contains only offsets relative to the base of
* the mdev at this point, so make them absolute.
*/
- for (i = 0; i < ARRAY_SIZE(mpls_table) - 1; i++)
+ for (i = 0; i < table_size; i++)
table[i].data = (char *)net + (uintptr_t)table[i].data;

net->mpls.ctl = register_net_sysctl_sz(net, "net/mpls", table,
- ARRAY_SIZE(mpls_table));
+ table_size);
if (net->mpls.ctl == NULL) {
kfree(table);
return -ENOMEM;
diff --git a/net/unix/sysctl_net_unix.c b/net/unix/sysctl_net_unix.c
index 3e84b31c355a..ae45d4cfac39 100644
--- a/net/unix/sysctl_net_unix.c
+++ b/net/unix/sysctl_net_unix.c
@@ -19,7 +19,6 @@ static struct ctl_table unix_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec
},
- { }
};

int __net_init unix_sysctl_register(struct net *net)

--
2.43.0