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net: Remove the now superfluous sentinel elements from ctl_table array
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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%[email protected]/)

* 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 c899710
  ("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 <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
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@Joelgranados @davem330
Joelgranados authored and davem330 committed May 3, 2024
1 parent a17ef9e commit ce21871
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Showing 6 changed files with 14 additions and 26 deletions.
5 changes: 1 addition & 4 deletions net/core/neighbour.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3733,7 +3733,7 @@ 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"),
Expand Down Expand Up @@ -3784,7 +3784,6 @@ static struct neigh_sysctl_table {
.extra2 = SYSCTL_INT_MAX,
.proc_handler = proc_dointvec_minmax,
},
{},
},
};

Expand Down Expand Up @@ -3812,8 +3811,6 @@ 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;
Expand Down
13 changes: 6 additions & 7 deletions net/core/sysctl_net_core.c
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Original file line number Diff line number Diff line change
Expand Up @@ -661,7 +661,6 @@ static struct ctl_table net_core_table[] = {
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ZERO,
},
{ }
};

static struct ctl_table netns_core_table[] = {
Expand Down Expand Up @@ -698,7 +697,6 @@ 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)
Expand All @@ -716,20 +714,21 @@ __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)) {
int i;
tbl = kmemdup(tbl, sizeof(netns_core_table), GFP_KERNEL);
if (tbl == NULL)
goto err_dup;

for (tmp = tbl; tmp->procname; tmp++)
tmp->data += (char *)net - (char *)&init_net;
for (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;

Expand Down
2 changes: 0 additions & 2 deletions net/dccp/sysctl.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down
6 changes: 1 addition & 5 deletions net/ieee802154/6lowpan/reassembly.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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 */
Expand All @@ -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)
Expand All @@ -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;
Expand Down
13 changes: 6 additions & 7 deletions net/mpls/af_mpls.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1377,13 +1377,13 @@ 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;
Expand All @@ -1395,16 +1395,15 @@ 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;
}

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;

Expand Down Expand Up @@ -2653,11 +2652,11 @@ static const struct ctl_table mpls_table[] = {
.extra1 = SYSCTL_ONE,
.extra2 = &ttl_max,
},
{ }
};

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

Expand All @@ -2673,11 +2672,11 @@ 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;
Expand Down
1 change: 0 additions & 1 deletion net/unix/sysctl_net_unix.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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)
Expand Down

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