LinuxLists.cc - [PATCH 0/4] sysctl: Remove sentinel elements from networking

2024-03-14 19:21:06

Subject: [PATCH 0/4] sysctl: Remove sentinel elements from networking

From: Joel Granados <[email protected]>

What?
These commits remove the sentinel element (last empty element) from the
sysctl arrays of all the files under the "net/" directory that register
a sysctl array. The merging of the preparation patches [4] to mainline
allows us to just remove sentinel elements without changing behavior.
This is safe because the sysctl registration code (register_sysctl() and
friends) use the array size in addition to checking for a sentinel [1].

Why?
By removing the sysctl sentinel elements we avoid kernel bloat as
ctl_table arrays get moved out of kernel/sysctl.c into their own
respective subsystems. This move was started long ago to avoid merge
conflicts; the sentinel removal bit came after Mathew Wilcox suggested
it to avoid bloating the kernel by one element as arrays moved out. This
patchset will reduce the overall build time size of the kernel and run
time memory bloat by about ~64 bytes per declared ctl_table array (more
info here [5]).

When are we done?
There are 4 patchest (25 commits [2]) that are still outstanding to
completely remove the sentinels: files under "net/" (this patchset),
files under "kernel/" dir, misc dirs (files under mm/ security/ and
others) and the final set that removes the unneeded check for ->procname
== NULL.

Testing:
* Ran sysctl selftests (./tools/testing/selftests/sysctl/sysctl.sh)
* Ran this through 0-day with no errors or warnings

Savings in vmlinux:
A total of 64 bytes per sentinel is saved after removal; I measured in
x86_64 to give an idea of the aggregated savings. The actual savings
will depend on individual kernel configuration.
* bloat-o-meter
- The "yesall" config saves 3976 bytes (bloat-o-meter output [6])
- A reduced config [3] saves 1263 bytes (bloat-o-meter output [7])

Savings in allocated memory:
None in this set but will occur when the superfluous allocations are
removed from proc_sysctl.c. I include it here for context. The
estimated savings during boot for config [3] are 6272 bytes. See [8]
for how to measure it.

Comments/feedback greatly appreciated

Best
Joel

[1] https://lore.kernel.org/all/[email protected]/
[2] https://git.kernel.org/pub/scm/linux/kernel/git/joel.granados/linux.git/tag/?h=sysctl_remove_empty_elem_v5
[3] https://gist.github.com/Joelgranados/feaca7af5537156ca9b73aeaec093171
[4] https://lore.kernel.org/all/ZO5Yx5JFogGi%[email protected]/

[5]
Links Related to the ctl_table sentinel removal:
* Good summaries from Luis:
https://lore.kernel.org/all/ZO5Yx5JFogGi%[email protected]/
https://lore.kernel.org/all/[email protected]/
* Patches adjusting sysctl register calls:
https://lore.kernel.org/all/[email protected]/
https://lore.kernel.org/all/[email protected]/
* Discussions about expectations and approach
https://lore.kernel.org/all/[email protected]
https://lore.kernel.org/all/[email protected]

[6]
add/remove: 0/1 grow/shrink: 2/67 up/down: 76/-4052 (-3976)
Function old new delta
llc_sysctl_init 306 377 +71
nf_log_net_init 866 871 +5
sysctl_core_net_init 375 366 -9
lowpan_frags_init_net 618 598 -20
ip_vs_control_net_init_sysctl 2446 2422 -24
sysctl_route_net_init 521 493 -28
__addrconf_sysctl_register 678 650 -28
xfrm_sysctl_init 405 374 -31
mpls_net_init 367 334 -33
sctp_sysctl_net_register 386 346 -40
__ip_vs_lblcr_init 546 501 -45
__ip_vs_lblc_init 546 501 -45
neigh_sysctl_register 1011 958 -53
mpls_dev_sysctl_register 475 419 -56
ipv6_route_sysctl_init 450 394 -56
xs_tunables_table 448 384 -64
xr_tunables_table 448 384 -64
xfrm_table 320 256 -64
xfrm6_policy_table 128 64 -64
xfrm4_policy_table 128 64 -64
x25_table 448 384 -64
vs_vars 1984 1920 -64
unix_table 128 64 -64
tipc_table 448 384 -64
svcrdma_parm_table 832 768 -64
smc_table 512 448 -64
sctp_table 256 192 -64
sctp_net_table 2304 2240 -64
rxrpc_sysctl_table 704 640 -64
rose_table 704 640 -64
rds_tcp_sysctl_table 192 128 -64
rds_sysctl_rds_table 384 320 -64
rds_ib_sysctl_table 384 320 -64
phonet_table 128 64 -64
nr_table 832 768 -64
nf_log_sysctl_table 768 704 -64
nf_log_sysctl_ftable 128 64 -64
nf_ct_sysctl_table 3200 3136 -64
nf_ct_netfilter_table 128 64 -64
nf_ct_frag6_sysctl_table 256 192 -64
netns_core_table 320 256 -64
net_core_table 2176 2112 -64
neigh_sysctl_template 1416 1352 -64
mptcp_sysctl_table 576 512 -64
mpls_dev_table 128 64 -64
lowpan_frags_ns_ctl_table 256 192 -64
lowpan_frags_ctl_table 128 64 -64
llc_station_table 64 - -64
llc2_timeout_table 320 256 -64
ipv6_table_template 1344 1280 -64
ipv6_route_table_template 768 704 -64
ipv6_rotable 320 256 -64
ipv6_icmp_table_template 448 384 -64
ipv4_table 1024 960 -64
ipv4_route_table 832 768 -64
ipv4_route_netns_table 320 256 -64
ipv4_net_table 7552 7488 -64
ip6_frags_ns_ctl_table 256 192 -64
ip6_frags_ctl_table 128 64 -64
ip4_frags_ns_ctl_table 320 256 -64
ip4_frags_ctl_table 128 64 -64
devinet_sysctl 2184 2120 -64
debug_table 384 320 -64
dccp_default_table 576 512 -64
ctl_forward_entry 128 64 -64
brnf_table 448 384 -64
ax25_param_table 960 896 -64
atalk_table 320 256 -64
addrconf_sysctl 3904 3840 -64
vs_vars_table 256 128 -128
Total: Before=440631035, After=440627059, chg -0.00%

[7]
add/remove: 0/0 grow/shrink: 1/22 up/down: 8/-1263 (-1255)
Function old new delta
sysctl_route_net_init 189 197 +8
__addrconf_sysctl_register 306 294 -12
ipv6_route_sysctl_init 201 185 -16
neigh_sysctl_register 385 366 -19
unix_table 128 64 -64
netns_core_table 256 192 -64
net_core_table 1664 1600 -64
neigh_sysctl_template 1416 1352 -64
ipv6_table_template 1344 1280 -64
ipv6_route_table_template 768 704 -64
ipv6_rotable 192 128 -64
ipv6_icmp_table_template 448 384 -64
ipv4_table 768 704 -64
ipv4_route_table 832 768 -64
ipv4_route_netns_table 320 256 -64
ipv4_net_table 7040 6976 -64
ip6_frags_ns_ctl_table 256 192 -64
ip6_frags_ctl_table 128 64 -64
ip4_frags_ns_ctl_table 320 256 -64
ip4_frags_ctl_table 128 64 -64
devinet_sysctl 2184 2120 -64
ctl_forward_entry 128 64 -64
addrconf_sysctl 3392 3328 -64
Total: Before=8523801, After=8522546, chg -0.01%

[8]
To measure the in memory savings apply this on top of this patchset.

"
diff --git i/fs/proc/proc_sysctl.c w/fs/proc/proc_sysctl.c
index 37cde0efee57..896c498600e8 100644
--- i/fs/proc/proc_sysctl.c
+++ w/fs/proc/proc_sysctl.c
@@ -966,6 +966,7 @@ static struct ctl_dir *new_dir(struct ctl_table_set *set,
table[0].procname = new_name;
table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO;
init_header(&new->header, set->dir.header.root, set, node, table, 1);
+ printk("%ld sysctl saved mem kzalloc\n", sizeof(struct ctl_table));

return new;
}
@@ -1189,6 +1190,7 @@ static struct ctl_table_header *new_links(struct ctl_dir *dir, s>
link_name += len;
link++;
}
+ printk("%ld sysctl saved mem kzalloc\n", sizeof(struct ctl_table));
init_header(links, dir->header.root, dir->header.set, node, link_table,
head->ctl_table_size);
links->nreg = nr_entries;
"
and then run the following bash script in the kernel:

accum=0
for n in $(dmesg | grep kzalloc | awk '{print $3}') ; do
accum=$(calc "$accum + $n")
done
echo $accum

Signed-off-by: Joel Granados <[email protected]>

--

---
Joel Granados (4):
networking: Remove the now superfluous sentinel elements from ctl_table array
netfilter: Remove the now superfluous sentinel elements from ctl_table array
appletalk: Remove the now superfluous sentinel elements from ctl_table array
ax.25: Remove the now superfluous sentinel elements from ctl_table array

net/appletalk/sysctl_net_atalk.c | 1 -
net/ax25/sysctl_net_ax25.c | 5 ++---
net/bridge/br_netfilter_hooks.c | 1 -
net/core/neighbour.c | 5 +----
net/core/sysctl_net_core.c | 9 ++++-----
net/dccp/sysctl.c | 2 --
net/ieee802154/6lowpan/reassembly.c | 6 +-----
net/ipv4/devinet.c | 5 ++---
net/ipv4/ip_fragment.c | 2 --
net/ipv4/route.c | 8 ++------
net/ipv4/sysctl_net_ipv4.c | 7 +++----
net/ipv4/xfrm4_policy.c | 1 -
net/ipv6/addrconf.c | 5 +----
net/ipv6/icmp.c | 1 -
net/ipv6/netfilter/nf_conntrack_reasm.c | 1 -
net/ipv6/reassembly.c | 2 --
net/ipv6/route.c | 5 -----
net/ipv6/sysctl_net_ipv6.c | 4 +---
net/ipv6/xfrm6_policy.c | 1 -
net/llc/sysctl_net_llc.c | 8 ++------
net/mpls/af_mpls.c | 3 +--
net/mptcp/ctrl.c | 1 -
net/netfilter/ipvs/ip_vs_ctl.c | 5 +----
net/netfilter/ipvs/ip_vs_lblc.c | 5 +----
net/netfilter/ipvs/ip_vs_lblcr.c | 5 +----
net/netfilter/nf_conntrack_standalone.c | 6 +-----
net/netfilter/nf_log.c | 3 +--
net/netrom/sysctl_net_netrom.c | 1 -
net/phonet/sysctl.c | 1 -
net/rds/ib_sysctl.c | 1 -
net/rds/sysctl.c | 1 -
net/rds/tcp.c | 1 -
net/rose/sysctl_net_rose.c | 1 -
net/rxrpc/sysctl.c | 1 -
net/sctp/sysctl.c | 6 +-----
net/smc/smc_sysctl.c | 1 -
net/sunrpc/sysctl.c | 1 -
net/sunrpc/xprtrdma/svc_rdma.c | 1 -
net/sunrpc/xprtrdma/transport.c | 1 -
net/sunrpc/xprtsock.c | 1 -
net/tipc/sysctl.c | 1 -
net/unix/sysctl_net_unix.c | 1 -
net/x25/sysctl_net_x25.c | 1 -
net/xfrm/xfrm_sysctl.c | 5 +----
44 files changed, 27 insertions(+), 106 deletions(-)
---
base-commit: e8f897f4afef0031fe618a8e94127a0934896aba
change-id: 20240311-jag-sysctl_remset_net-d403a1a93d6b

Best regards,
--
Joel Granados <[email protected]>

2024-03-14 19:21:12

by Joel Granados via B4 Relay

[permalink] [raw]

Subject: [PATCH 1/4] networking: Remove the now superfluous sentinel elements from ctl_table array

From: Joel Granados <[email protected]>

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 extra element in ctl_table arrays declarations
* Remove instances where an array element is zeroed out to make it look
like a sentinel. 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 that tests for procname == NULL with
one that depends on array size
* Removed the "-1" that adjusted for having an extra empty element when
looping over ctl_table arrays
* Removing the unprivileged user check in ipv6_route_sysctl_init is
safe as it is replaced by calling ipv6_route_sysctl_table_size;
introduced in commit c899710fe7f9 ("networking: Update to
register_net_sysctl_sz")
* Replace empty array registration with the register_net_sysctl_sz call.

Signed-off-by: Joel Granados <[email protected]>
---
net/core/neighbour.c | 5 +----
net/core/sysctl_net_core.c | 9 ++++-----
net/dccp/sysctl.c | 2 --
net/ieee802154/6lowpan/reassembly.c | 6 +-----
net/ipv4/devinet.c | 5 ++---
net/ipv4/ip_fragment.c | 2 --
net/ipv4/route.c | 8 ++------
net/ipv4/sysctl_net_ipv4.c | 7 +++----
net/ipv4/xfrm4_policy.c | 1 -
net/ipv6/addrconf.c | 5 +----
net/ipv6/icmp.c | 1 -
net/ipv6/reassembly.c | 2 --
net/ipv6/route.c | 5 -----
net/ipv6/sysctl_net_ipv6.c | 4 +---
net/ipv6/xfrm6_policy.c | 1 -
net/llc/sysctl_net_llc.c | 8 ++------
net/mpls/af_mpls.c | 3 +--
net/mptcp/ctrl.c | 1 -
net/netrom/sysctl_net_netrom.c | 1 -
net/phonet/sysctl.c | 1 -
net/rds/ib_sysctl.c | 1 -
net/rds/sysctl.c | 1 -
net/rds/tcp.c | 1 -
net/rose/sysctl_net_rose.c | 1 -
net/rxrpc/sysctl.c | 1 -
net/sctp/sysctl.c | 6 +-----
net/smc/smc_sysctl.c | 1 -
net/sunrpc/sysctl.c | 1 -
net/sunrpc/xprtrdma/svc_rdma.c | 1 -
net/sunrpc/xprtrdma/transport.c | 1 -
net/sunrpc/xprtsock.c | 1 -
net/tipc/sysctl.c | 1 -
net/unix/sysctl_net_unix.c | 1 -
net/x25/sysctl_net_x25.c | 1 -
net/xfrm/xfrm_sysctl.c | 5 +----
35 files changed, 20 insertions(+), 81 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 0f0cb1465e08..2cd068d8acae 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -646,7 +646,6 @@ static struct ctl_table net_core_table[] = {
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ZERO,
},
- { }
};

static struct ctl_table netns_core_table[] = {
@@ -683,7 +682,6 @@ 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)
@@ -701,7 +699,8 @@ __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;
+ struct ctl_table *tbl;
+ size_t table_size = ARRAY_SIZE(netns_core_table);

tbl = netns_core_table;
if (!net_eq(net, &init_net)) {
@@ -709,8 +708,8 @@ 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,
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/ipv4/devinet.c b/net/ipv4/devinet.c
index bc74f131fe4d..80d726b686c0 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -2546,7 +2546,7 @@ static int ipv4_doint_and_flush(struct ctl_table *ctl, int write,

static struct devinet_sysctl_table {
struct ctl_table_header *sysctl_header;
- struct ctl_table devinet_vars[__IPV4_DEVCONF_MAX];
+ struct ctl_table devinet_vars[IPV4_DEVCONF_MAX];
} devinet_sysctl = {
.devinet_vars = {
DEVINET_SYSCTL_COMPLEX_ENTRY(FORWARDING, "forwarding",
@@ -2609,7 +2609,7 @@ static int __devinet_sysctl_register(struct net *net, char *dev_name,
if (!t)
goto out;

- for (i = 0; i < ARRAY_SIZE(t->devinet_vars) - 1; i++) {
+ for (i = 0; i < ARRAY_SIZE(t->devinet_vars); i++) {
t->devinet_vars[i].data += (char *)p - (char *)&ipv4_devconf;
t->devinet_vars[i].extra1 = p;
t->devinet_vars[i].extra2 = net;
@@ -2683,7 +2683,6 @@ static struct ctl_table ctl_forward_entry[] = {
.extra1 = &ipv4_devconf,
.extra2 = &init_net,
},
- { },
};
#endif

diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index a4941f53b523..e308779ed77b 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -580,7 +580,6 @@ static struct ctl_table ip4_frags_ns_ctl_table[] = {
.proc_handler = proc_dointvec_minmax,
.extra1 = &dist_min,
},
- { }
};

/* secret interval has been deprecated */
@@ -593,7 +592,6 @@ static struct ctl_table ip4_frags_ctl_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec_jiffies,
},
- { }
};

static int __net_init ip4_frags_ns_ctl_register(struct net *net)
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 16615d107cf0..ad1a7ebf45c5 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -3509,7 +3509,6 @@ static struct ctl_table ipv4_route_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec,
},
- { }
};

static const char ipv4_route_flush_procname[] = "flush";
@@ -3543,7 +3542,6 @@ static struct ctl_table ipv4_route_netns_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec,
},
- { },
};

static __net_init int sysctl_route_net_init(struct net *net)
@@ -3561,16 +3559,14 @@ static __net_init int sysctl_route_net_init(struct net *net)

/* Don't export non-whitelisted sysctls to unprivileged users */
if (net->user_ns != &init_user_ns) {
- if (tbl[0].procname != ipv4_route_flush_procname) {
- tbl[0].procname = NULL;
+ if (tbl[0].procname != ipv4_route_flush_procname)
table_size = 0;
- }
}

/* Update the variables to point into the current struct net
* except for the first element flush
*/
- for (i = 1; i < ARRAY_SIZE(ipv4_route_netns_table) - 1; i++)
+ for (i = 1; i < table_size; i++)
tbl[i].data += (void *)net - (void *)&init_net;
}
tbl[0].extra1 = net;
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 7e4f16a7dcc1..c8dae8fc682a 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -575,7 +575,6 @@ static struct ctl_table ipv4_table[] = {
.extra1 = &sysctl_fib_sync_mem_min,
.extra2 = &sysctl_fib_sync_mem_max,
},
- { }
};

static struct ctl_table ipv4_net_table[] = {
@@ -1502,12 +1501,12 @@ static struct ctl_table ipv4_net_table[] = {
.proc_handler = proc_dou8vec_minmax,
.extra1 = SYSCTL_ONE,
},
- { }
};

static __net_init int ipv4_sysctl_init_net(struct net *net)
{
struct ctl_table *table;
+ size_t table_size = ARRAY_SIZE(ipv4_net_table);

table = ipv4_net_table;
if (!net_eq(net, &init_net)) {
@@ -1517,7 +1516,7 @@ static __net_init int ipv4_sysctl_init_net(struct net *net)
if (!table)
goto err_alloc;

- for (i = 0; i < ARRAY_SIZE(ipv4_net_table) - 1; i++) {
+ for (i = 0; i < table_size; i++) {
if (table[i].data) {
/* Update the variables to point into
* the current struct net
@@ -1533,7 +1532,7 @@ static __net_init int ipv4_sysctl_init_net(struct net *net)
}

net->ipv4.ipv4_hdr = register_net_sysctl_sz(net, "net/ipv4", table,
- ARRAY_SIZE(ipv4_net_table));
+ table_size);
if (!net->ipv4.ipv4_hdr)
goto err_reg;

diff --git a/net/ipv4/xfrm4_policy.c b/net/ipv4/xfrm4_policy.c
index c33bca2c3841..4c74fec034c5 100644
--- a/net/ipv4/xfrm4_policy.c
+++ b/net/ipv4/xfrm4_policy.c
@@ -152,7 +152,6 @@ static struct ctl_table xfrm4_policy_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec,
},
- { }
};

static __net_init int xfrm4_net_sysctl_init(struct net *net)
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 055230b669cf..55c476332607 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -7130,9 +7130,6 @@ static const struct ctl_table addrconf_sysctl[] = {
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_TWO,
},
- {
- /* sentinel */
- }
};

static int __addrconf_sysctl_register(struct net *net, char *dev_name,
@@ -7146,7 +7143,7 @@ static int __addrconf_sysctl_register(struct net *net, char *dev_name,
if (!table)
goto out;

- for (i = 0; table[i].data; i++) {
+ for (i = 0; i < ARRAY_SIZE(addrconf_sysctl); i++) {
table[i].data += (char *)p - (char *)&ipv6_devconf;
/* If one of these is already set, then it is not safe to
* overwrite either of them: this makes proc_dointvec_minmax
diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c
index 1635da07285f..91cbf8e8009f 100644
--- a/net/ipv6/icmp.c
+++ b/net/ipv6/icmp.c
@@ -1206,7 +1206,6 @@ static struct ctl_table ipv6_icmp_table_template[] = {
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_ONE,
},
- { },
};

struct ctl_table * __net_init ipv6_icmp_sysctl_init(struct net *net)
diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
index 5ebc47da1000..ba077bb8078c 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -436,7 +436,6 @@ static struct ctl_table ip6_frags_ns_ctl_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec_jiffies,
},
- { }
};

/* secret interval has been deprecated */
@@ -449,7 +448,6 @@ static struct ctl_table ip6_frags_ctl_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec_jiffies,
},
- { }
};

static int __net_init ip6_frags_ns_sysctl_register(struct net *net)
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index ef815ba583a8..2c43eb82e072 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -6417,7 +6417,6 @@ static struct ctl_table ipv6_route_table_template[] = {
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_ONE,
},
- { }
};

struct ctl_table * __net_init ipv6_route_sysctl_init(struct net *net)
@@ -6441,10 +6440,6 @@ struct ctl_table * __net_init ipv6_route_sysctl_init(struct net *net)
table[8].data = &net->ipv6.sysctl.ip6_rt_min_advmss;
table[9].data = &net->ipv6.sysctl.ip6_rt_gc_min_interval;
table[10].data = &net->ipv6.sysctl.skip_notify_on_dev_down;
-
- /* Don't export sysctls to unprivileged users */
- if (net->user_ns != &init_user_ns)
- table[1].procname = NULL;
}

return table;
diff --git a/net/ipv6/sysctl_net_ipv6.c b/net/ipv6/sysctl_net_ipv6.c
index 888676163e90..9f40bb12fbdd 100644
--- a/net/ipv6/sysctl_net_ipv6.c
+++ b/net/ipv6/sysctl_net_ipv6.c
@@ -213,7 +213,6 @@ static struct ctl_table ipv6_table_template[] = {
.proc_handler = proc_doulongvec_minmax,
.extra2 = &ioam6_id_wide_max,
},
- { }
};

static struct ctl_table ipv6_rotable[] = {
@@ -248,7 +247,6 @@ static struct ctl_table ipv6_rotable[] = {
.proc_handler = proc_dointvec,
},
#endif /* CONFIG_NETLABEL */
- { }
};

static int __net_init ipv6_sysctl_net_init(struct net *net)
@@ -264,7 +262,7 @@ static int __net_init ipv6_sysctl_net_init(struct net *net)
if (!ipv6_table)
goto out;
/* Update the variables to point into the current struct net */
- for (i = 0; i < ARRAY_SIZE(ipv6_table_template) - 1; i++)
+ for (i = 0; i < ARRAY_SIZE(ipv6_table_template); i++)
ipv6_table[i].data += (void *)net - (void *)&init_net;

ipv6_route_table = ipv6_route_sysctl_init(net);
diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c
index 42fb6996b077..499b5f5c19fc 100644
--- a/net/ipv6/xfrm6_policy.c
+++ b/net/ipv6/xfrm6_policy.c
@@ -184,7 +184,6 @@ static struct ctl_table xfrm6_policy_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec,
},
- { }
};

static int __net_init xfrm6_net_sysctl_init(struct net *net)
diff --git a/net/llc/sysctl_net_llc.c b/net/llc/sysctl_net_llc.c
index 8443a6d841b0..72e101135f8c 100644
--- a/net/llc/sysctl_net_llc.c
+++ b/net/llc/sysctl_net_llc.c
@@ -44,11 +44,6 @@ static struct ctl_table llc2_timeout_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec_jiffies,
},
- { },
-};
-
-static struct ctl_table llc_station_table[] = {
- { },
};

static struct ctl_table_header *llc2_timeout_header;
@@ -56,8 +51,9 @@ static struct ctl_table_header *llc_station_header;

int __init llc_sysctl_init(void)
{
+ struct ctl_table empty[1] = {};
llc2_timeout_header = register_net_sysctl(&init_net, "net/llc/llc2/timeout", llc2_timeout_table);
- llc_station_header = register_net_sysctl(&init_net, "net/llc/station", llc_station_table);
+ llc_station_header = register_net_sysctl_sz(&init_net, "net/llc/station", empty, 0);

if (!llc2_timeout_header || !llc_station_header) {
llc_sysctl_exit();
diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
index 1af29af65388..d09ee21fa93c 100644
--- a/net/mpls/af_mpls.c
+++ b/net/mpls/af_mpls.c
@@ -1393,7 +1393,6 @@ 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,
@@ -2687,7 +2686,7 @@ 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 < ARRAY_SIZE(mpls_table); i++)
table[i].data = (char *)net + (uintptr_t)table[i].data;

net->mpls.ctl = register_net_sysctl_sz(net, "net/mpls", table,
diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c
index 13fe0748dde8..8bf7c26a0878 100644
--- a/net/mptcp/ctrl.c
+++ b/net/mptcp/ctrl.c
@@ -156,7 +156,6 @@ static struct ctl_table mptcp_sysctl_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec_jiffies,
},
- {}
};

static int mptcp_pernet_new_table(struct net *net, struct mptcp_pernet *pernet)
diff --git a/net/netrom/sysctl_net_netrom.c b/net/netrom/sysctl_net_netrom.c
index 79fb2d3f477b..7dc0fa628f2e 100644
--- a/net/netrom/sysctl_net_netrom.c
+++ b/net/netrom/sysctl_net_netrom.c
@@ -140,7 +140,6 @@ static struct ctl_table nr_table[] = {
.extra1 = &min_reset,
.extra2 = &max_reset
},
- { }
};

int __init nr_register_sysctl(void)
diff --git a/net/phonet/sysctl.c b/net/phonet/sysctl.c
index 0d0bf41381c2..82fc22467a09 100644
--- a/net/phonet/sysctl.c
+++ b/net/phonet/sysctl.c
@@ -81,7 +81,6 @@ static struct ctl_table phonet_table[] = {
.mode = 0644,
.proc_handler = proc_local_port_range,
},
- { }
};

int __init phonet_sysctl_init(void)
diff --git a/net/rds/ib_sysctl.c b/net/rds/ib_sysctl.c
index e4e41b3afce7..2af678e71e3c 100644
--- a/net/rds/ib_sysctl.c
+++ b/net/rds/ib_sysctl.c
@@ -103,7 +103,6 @@ static struct ctl_table rds_ib_sysctl_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec,
},
- { }
};

void rds_ib_sysctl_exit(void)
diff --git a/net/rds/sysctl.c b/net/rds/sysctl.c
index e381bbcd9cc1..025f518a4349 100644
--- a/net/rds/sysctl.c
+++ b/net/rds/sysctl.c
@@ -89,7 +89,6 @@ static struct ctl_table rds_sysctl_rds_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec,
},
- { }
};

void rds_sysctl_exit(void)
diff --git a/net/rds/tcp.c b/net/rds/tcp.c
index 2dba7505b414..d8111ac83bb6 100644
--- a/net/rds/tcp.c
+++ b/net/rds/tcp.c
@@ -86,7 +86,6 @@ static struct ctl_table rds_tcp_sysctl_table[] = {
.proc_handler = rds_tcp_skbuf_handler,
.extra1 = &rds_tcp_min_rcvbuf,
},
- { }
};

u32 rds_tcp_write_seq(struct rds_tcp_connection *tc)
diff --git a/net/rose/sysctl_net_rose.c b/net/rose/sysctl_net_rose.c
index d391d7758f52..d801315b7083 100644
--- a/net/rose/sysctl_net_rose.c
+++ b/net/rose/sysctl_net_rose.c
@@ -112,7 +112,6 @@ static struct ctl_table rose_table[] = {
.extra1 = &min_window,
.extra2 = &max_window
},
- { }
};

void __init rose_register_sysctl(void)
diff --git a/net/rxrpc/sysctl.c b/net/rxrpc/sysctl.c
index ecaeb4ecfb58..dc5788a821f0 100644
--- a/net/rxrpc/sysctl.c
+++ b/net/rxrpc/sysctl.c
@@ -125,7 +125,6 @@ static struct ctl_table rxrpc_sysctl_table[] = {
.extra1 = (void *)SYSCTL_ONE,
.extra2 = (void *)&four,
},
- { }
};

int __init rxrpc_sysctl_init(void)
diff --git a/net/sctp/sysctl.c b/net/sctp/sysctl.c
index f65d6f92afcb..6894072af210 100644
--- a/net/sctp/sysctl.c
+++ b/net/sctp/sysctl.c
@@ -80,8 +80,6 @@ static struct ctl_table sctp_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec,
},
-
- { /* sentinel */ }
};

/* The following index defines are used in sctp_sysctl_net_register().
@@ -384,8 +382,6 @@ static struct ctl_table sctp_net_table[] = {
.extra1 = SYSCTL_ZERO,
.extra2 = &pf_expose_max,
},
-
- { /* sentinel */ }
};

static int proc_sctp_do_hmac_alg(struct ctl_table *ctl, int write,
@@ -604,7 +600,7 @@ int sctp_sysctl_net_register(struct net *net)
if (!table)
return -ENOMEM;

- for (i = 0; table[i].data; i++)
+ for (i = 0; i < ARRAY_SIZE(sctp_net_table); i++)
table[i].data += (char *)(&net->sctp) - (char *)&init_net.sctp;

table[SCTP_RTO_MIN_IDX].extra2 = &net->sctp.rto_max;
diff --git a/net/smc/smc_sysctl.c b/net/smc/smc_sysctl.c
index a5946d1b9d60..bd0b7e2f8824 100644
--- a/net/smc/smc_sysctl.c
+++ b/net/smc/smc_sysctl.c
@@ -90,7 +90,6 @@ static struct ctl_table smc_table[] = {
.extra1 = &conns_per_lgr_min,
.extra2 = &conns_per_lgr_max,
},
- { }
};

int __net_init smc_sysctl_net_init(struct net *net)
diff --git a/net/sunrpc/sysctl.c b/net/sunrpc/sysctl.c
index 93941ab12549..5f3170a1c9bb 100644
--- a/net/sunrpc/sysctl.c
+++ b/net/sunrpc/sysctl.c
@@ -160,7 +160,6 @@ static struct ctl_table debug_table[] = {
.mode = 0444,
.proc_handler = proc_do_xprt,
},
- { }
};

void
diff --git a/net/sunrpc/xprtrdma/svc_rdma.c b/net/sunrpc/xprtrdma/svc_rdma.c
index f86970733eb0..474f7a98fe9e 100644
--- a/net/sunrpc/xprtrdma/svc_rdma.c
+++ b/net/sunrpc/xprtrdma/svc_rdma.c
@@ -209,7 +209,6 @@ static struct ctl_table svcrdma_parm_table[] = {
.extra1 = &zero,
.extra2 = &zero,
},
- { },
};

static void svc_rdma_proc_cleanup(void)
diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c
index 29b0562d62e7..9a8ce5df83ca 100644
--- a/net/sunrpc/xprtrdma/transport.c
+++ b/net/sunrpc/xprtrdma/transport.c
@@ -137,7 +137,6 @@ static struct ctl_table xr_tunables_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec,
},
- { },
};

#endif
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 58f3dc8d0d71..fe4c01d60679 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -159,7 +159,6 @@ static struct ctl_table xs_tunables_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec_jiffies,
},
- { },
};

/*
diff --git a/net/tipc/sysctl.c b/net/tipc/sysctl.c
index 9fb65c988f7f..30d2e06e3d8c 100644
--- a/net/tipc/sysctl.c
+++ b/net/tipc/sysctl.c
@@ -91,7 +91,6 @@ static struct ctl_table tipc_table[] = {
.mode = 0644,
.proc_handler = proc_doulongvec_minmax,
},
- {}
};

int tipc_register_sysctl(void)
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)
diff --git a/net/x25/sysctl_net_x25.c b/net/x25/sysctl_net_x25.c
index e9802afa43d0..643f50874dfe 100644
--- a/net/x25/sysctl_net_x25.c
+++ b/net/x25/sysctl_net_x25.c
@@ -71,7 +71,6 @@ static struct ctl_table x25_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec,
},
- { },
};

int __init x25_register_sysctl(void)
diff --git a/net/xfrm/xfrm_sysctl.c b/net/xfrm/xfrm_sysctl.c
index 7fdeafc838a7..b0f542805e6e 100644
--- a/net/xfrm/xfrm_sysctl.c
+++ b/net/xfrm/xfrm_sysctl.c
@@ -38,7 +38,6 @@ static struct ctl_table xfrm_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec
},
- {}
};

int __net_init xfrm_sysctl_init(struct net *net)
@@ -57,10 +56,8 @@ int __net_init xfrm_sysctl_init(struct net *net)
table[3].data = &net->xfrm.sysctl_acq_expires;

/* 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;
- }

net->xfrm.sysctl_hdr = register_net_sysctl_sz(net, "net/core", table,
table_size);

--
2.43.0

2024-03-14 19:21:20

by Joel Granados via B4 Relay

[permalink] [raw]

Subject: [PATCH 2/4] netfilter: Remove the now superfluous sentinel elements from ctl_table array

2024-03-14 19:21:26

by Joel Granados via B4 Relay

[permalink] [raw]

Subject: [PATCH 3/4] appletalk: Remove the now superfluous sentinel elements from ctl_table array

2024-03-14 19:21:39

by Joel Granados via B4 Relay

[permalink] [raw]

Subject: [PATCH 4/4] ax.25: Remove the now superfluous sentinel elements from ctl_table array

2024-03-14 22:42:58

by Jakub Kicinski

[permalink] [raw]

Subject: Re: [PATCH 0/4] sysctl: Remove sentinel elements from networking

On Thu, 14 Mar 2024 20:20:40 +0100 Joel Granados via B4 Relay wrote:
> These commits remove the sentinel element (last empty element) from the
> sysctl arrays of all the files under the "net/" directory that register
> a sysctl array. The merging of the preparation patches [4] to mainline
> allows us to just remove sentinel elements without changing behavior.
> This is safe because the sysctl registration code (register_sysctl() and
> friends) use the array size in addition to checking for a sentinel [1].

Thanks, but please resend after the merge window, we don't apply
code to -next until -rc1 is cut.
--
pw-bot: defer