diff mbox series

[07/10] printk: Remove the now superfluous sentinel elements from ctl_table array

Message ID 20231107-jag-sysctl_remove_empty_elem_kernel-v1-7-e4ce1388dfa0@samsung.com (mailing list archive)
State Not Applicable
Headers show
Series [01/10] kernel misc: Remove the now superfluous sentinel elements from ctl_table array | expand

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bpf/vmtest-bpf-next-PR success PR summary
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netdev/tree_selection success Guessed tree name to be net-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1352 this patch: 1352
netdev/cc_maintainers success CCed 5 of 5 maintainers
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Commit Message

Joel Granados via B4 Relay Nov. 7, 2023, 1:45 p.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/)

rm sentinel element from printk_sysctls

Signed-off-by: Joel Granados <j.granados@samsung.com>
---
 kernel/printk/sysctl.c | 1 -
 1 file changed, 1 deletion(-)

Comments

Petr Mladek Nov. 28, 2023, 2:07 p.m. UTC | #1 
On Tue 2023-11-07 14:45:07, Joel Granados via B4 Relay wrote:
> 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/)
> 
> rm sentinel element from printk_sysctls
> 
> Signed-off-by: Joel Granados <j.granados@samsung.com>

I am a bit sceptical if the size and time reduction is worth the
effort. I feel that this change makes the access a bit less secure.

Well, almost all arrays are static so that it should just work.
The patch does what it says. Feel free to use:

Reviewed-by: Petr Mladek <pmladek@suse.com>

Best Regards,
Petr
Joel Granados Dec. 4, 2023, 8:56 a.m. UTC | #2 
Hey Petr

I missed this message somehow....

On Tue, Nov 28, 2023 at 03:07:43PM +0100, Petr Mladek wrote:
> On Tue 2023-11-07 14:45:07, Joel Granados via B4 Relay wrote:
> > 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/)
> > 
> > rm sentinel element from printk_sysctls
> > 
> > Signed-off-by: Joel Granados <j.granados@samsung.com>
> 
> I am a bit sceptical if the size and time reduction is worth the
> effort. I feel that this change makes the access a bit less secure.
In what way "less secure"? Can you expand on that?

Notice that if you pass a pointer to the register functions, you will
get a warning/error on compilation.

> 
> Well, almost all arrays are static so that it should just work.
> The patch does what it says. Feel free to use:
Thx for the review. will do.

> 
> Reviewed-by: Petr Mladek <pmladek@suse.com>
> 
> Best Regards,
> Petr
Petr Mladek Dec. 6, 2023, 9:55 a.m. UTC | #3 
On Mon 2023-12-04 09:56:28, Joel Granados wrote:
> Hey Petr
> 
> I missed this message somehow....
> 
> On Tue, Nov 28, 2023 at 03:07:43PM +0100, Petr Mladek wrote:
> > On Tue 2023-11-07 14:45:07, Joel Granados via B4 Relay wrote:
> > > 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/)
> > > 
> > > rm sentinel element from printk_sysctls
> > > 
> > > Signed-off-by: Joel Granados <j.granados@samsung.com>
> > 
> > I am a bit sceptical if the size and time reduction is worth the
> > effort. I feel that this change makes the access a bit less secure.
> In what way "less secure"? Can you expand on that?
> 
> Notice that if you pass a pointer to the register functions, you will
> get a warning/error on compilation.

I have vague memories that some arrays were not static or the length
has been somehow manipulated. But I might be wrong.

You are right that it should be safe with the static arrays.
And the NULL sentinel might be more error-prone after all.

Let's forget my mumbles.

Best Regards,
Petr
diff mbox series

Patch

diff --git a/kernel/printk/sysctl.c b/kernel/printk/sysctl.c
index c228343eeb97..3e47dedce9e5 100644
--- a/kernel/printk/sysctl.c
+++ b/kernel/printk/sysctl.c
@@ -76,7 +76,6 @@  static struct ctl_table printk_sysctls[] = {
 		.extra1		= SYSCTL_ZERO,
 		.extra2		= SYSCTL_TWO,
 	},
-	{}
 };
 
 void __init printk_sysctl_init(void)