diff mbox series

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

Message ID 20240426-jag-sysctl_remset_net-v5-1-e3b12f6111a6@samsung.com (mailing list archive)
State Superseded, archived
Headers show
Series [v5,1/8] net: Remove the now superfluous sentinel elements from ctl_table array | expand

Commit Message

Joel Granados via B4 Relay April 26, 2024, 10:46 a.m. UTC 
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(-)

Comments

Sabrina Dubroca April 29, 2024, 8:53 a.m. UTC | #1 
2024-04-26, 12:46:53 +0200, Joel Granados via B4 Relay wrote:
> 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
[...]
> @@ -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;

Some coding style nits in case you re-post:

> +		for (int i = 0; i < table_size; ++i)

move the declaration of int i out of the for (), it's almost never
written this way (at least in networking)

> +			(tbl + i)->data += (char *)net - (char *)&init_net;

                        tbl[i].data = ...

is more in line with other similar functions in the rest of net/


[...]
> 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
[...]
> @@ -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);

This table still has a {} as its final element. It should be gone too?
Joel Granados April 29, 2024, 12:33 p.m. UTC | #2 
On Mon, Apr 29, 2024 at 10:53:47AM +0200, Sabrina Dubroca wrote:
> 2024-04-26, 12:46:53 +0200, Joel Granados via B4 Relay wrote:
> > 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
> [...]
> > @@ -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;
> 
> Some coding style nits in case you re-post:
Thx. I will, so please scream if you see more issues.

> 
> > +		for (int i = 0; i < table_size; ++i)
> 
> move the declaration of int i out of the for (), it's almost never
> written this way (at least in networking)
done

> 
> > +			(tbl + i)->data += (char *)net - (char *)&init_net;
> 
>                         tbl[i].data = ...
> 
> is more in line with other similar functions in the rest of net/
done

> 
> 
> [...]
> > 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
> [...]
> > @@ -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);
> 
> This table still has a {} as its final element. It should be gone too?
Now, how did that get away?  I'll run my coccinelle scripts once more to
make sure that I don't have more of these hiding in the shadows.

Thx for your feedback

Best
Sabrina Dubroca April 29, 2024, 2:49 p.m. UTC | #3 
2024-04-29, 14:33:15 +0200, Joel Granados wrote:
> On Mon, Apr 29, 2024 at 10:53:47AM +0200, Sabrina Dubroca wrote:
> > 2024-04-26, 12:46:53 +0200, Joel Granados via B4 Relay wrote:
> > > 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
> > [...]
> > > @@ -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;
> > 
> > Some coding style nits in case you re-post:
> Thx. I will, so please scream if you see more issues.

I've gone through the whole series and didn't see anything more.

> > > +		for (int i = 0; i < table_size; ++i)
> > 
> > move the declaration of int i out of the for (), it's almost never
> > written this way (at least in networking)
> done
> 
> > 
> > > +			(tbl + i)->data += (char *)net - (char *)&init_net;
> > 
> >                         tbl[i].data = ...
> > 
> > is more in line with other similar functions in the rest of net/
> done
> 
> > 
> > 
> > [...]
> > > 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
> > [...]
> > > @@ -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);
> > 
> > This table still has a {} as its final element. It should be gone too?
> Now, how did that get away?  I'll run my coccinelle scripts once more to
> make sure that I don't have more of these hiding in the shadows.

I didn't spot any other with a dumb

    sed -n '<line>,^};/p' <file>

(with file/line produced by git grep 'struct ctl_table' -- net)


Thanks.
Joel Granados April 30, 2024, 12:41 p.m. UTC | #4 
On Mon, Apr 29, 2024 at 04:49:18PM +0200, Sabrina Dubroca wrote:
> 2024-04-29, 14:33:15 +0200, Joel Granados wrote:
> > On Mon, Apr 29, 2024 at 10:53:47AM +0200, Sabrina Dubroca wrote:
> > > 2024-04-26, 12:46:53 +0200, Joel Granados via B4 Relay wrote:
...
> > > >  {
> > > > +	size_t table_size = ARRAY_SIZE(mpls_table);
> > > 
> > > This table still has a {} as its final element. It should be gone too?
> > Now, how did that get away?  I'll run my coccinelle scripts once more to
> > make sure that I don't have more of these hiding in the shadows.
> 
> I didn't spot any other with a dumb
> 
>     sed -n '<line>,^};/p' <file>

I used a coccinelle script:
  * ran it with `make coccicheck MODE=patch SPFLAGS="--in-place --debug" COCCI=script.cocci`
  * script:
    ```
    virtual patch

    @r1@
    identifier ctl_table_name;
    @@

    static struct ctl_table ctl_table_name[] = {
    ...
    -, {}
    };
    ```

and a gawk script
  * ran it with `for f in $(git grep -l "struct ctl_table") ; do script $f ; done`
  * script:
    ```
    #!/usr/bin/gawk -f

    BEGINFILE {
      RS=","
      has_struct = 0
    }

    /(static )?(const )?struct ctl_table/ {
      has_struct = 1
    }

    has_struct && /^(\n)?[\t ]*{(\n)*[\t ]*}/ {
      print "Filename : " FILENAME ", Record Number : " FNR
    }
    ```

At this point the coccinelle script gives me too many false positives
but the gawk is spot on. Thx for the sed one. Will make a note of it.

Best
diff mbox series

Patch

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)