[PATCH 00/15] sysctl: Remove sentinel elements from drivers

Joel Granados via B4 Relay posted 15 patches 7 months ago
Only 9 patches received!
There is a newer version of this series
drivers/base/firmware_loader/fallback_table.c |  3 +-
drivers/cdrom/cdrom.c                         |  3 +-
drivers/char/hpet.c                           |  3 +-
drivers/char/ipmi/ipmi_poweroff.c             |  3 +-
drivers/char/random.c                         |  3 +-
drivers/gpu/drm/i915/i915_perf.c              |  3 +-
drivers/hv/hv_common.c                        |  3 +-
drivers/infiniband/core/iwcm.c                |  3 +-
drivers/infiniband/core/ucma.c                |  3 +-
drivers/macintosh/mac_hid.c                   |  3 +-
drivers/md/md.c                               |  3 +-
drivers/misc/sgi-xp/xpc_main.c                |  6 ++--
drivers/net/vrf.c                             |  3 +-
drivers/parport/procfs.c                      | 42 ++++++++++++---------------
drivers/scsi/scsi_sysctl.c                    |  3 +-
drivers/scsi/sg.c                             |  3 +-
drivers/tty/tty_io.c                          |  3 +-
drivers/xen/balloon.c                         |  3 +-
18 files changed, 36 insertions(+), 60 deletions(-)
[PATCH 00/15] sysctl: Remove sentinel elements from drivers
Posted by Joel Granados via B4 Relay 7 months ago
From: Joel Granados <j.granados@samsung.com>

What?
These commits remove the sentinel element (last empty element) from the
sysctl arrays of all the files under the "drivers/" directory that use a
sysctl array for registration. The merging of the preparation patches
(in https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)
to mainline allows us to just remove sentinel elements without changing
behavior (more info here [1]).

These commits are part of a bigger set (here
https://github.com/Joelgranados/linux/tree/tag/sysctl_remove_empty_elem_V4)
that remove the ctl_table sentinel. Make the review process easier by
chunking the commits into manageable pieces. Each chunk can be reviewed
separately without noise from parallel sets.

Now that the architecture chunk has been mostly reviewed [6], we send
the "drivers/" directory. Once this one is done, it will be follwed by
"fs/*", "kernel/*", "net/*" and miscellaneous. The final set will remove
the unneeded check for ->procname == NULL.

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. I
have consolidated some links that shed light on the history of this
effort [2].

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

Size saving after removing all sentinels:
  These are the bytes that we save after removing all the sentinels
  (this plus all the other chunks). I included them to get an idea of
  how much memory we are talking about.
    * bloat-o-meter:
        - The "yesall" configuration results save 9158 bytes
          https://lore.kernel.org/all/20230621091000.424843-1-j.granados@samsung.com/
        - The "tiny" config + CONFIG_SYSCTL save 1215 bytes
          https://lore.kernel.org/all/20230809105006.1198165-1-j.granados@samsung.com/
    * memory usage:
        In memory savings are measured to be 7296 bytes. (here is how to
        measure [3])

Size saving after this patchset:
    * bloat-o-meter
        - The "yesall" config saves 2432 bytes [4]
        - The "tiny" config saves 64 bytes [5]
    * memory usage:
        In this case there were no bytes saved because I do not have any
        of the drivers in the patch. To measure it comment the printk in
        `new_dir` and uncomment the if conditional in `new_links` [3].

Comments/feedback greatly appreciated

Best
Joel

[1]
We are able to remove a sentinel table without behavioral change by
introducing a table_size argument in the same place where procname is
checked for NULL. The idea is for it to keep stopping when it hits
->procname == NULL, while the sentinel is still present. And when the
sentinel is removed, it will stop on the table_size. You can go to 
(https://lore.kernel.org/all/20230809105006.1198165-1-j.granados@samsung.com/)
for more information.

[2]
Links Related to the ctl_table sentinel removal:
* Good summary from Luis sent with the "pull request" for the
  preparation patches.
  https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/
* Another very good summary from Luis.
  https://lore.kernel.org/all/ZMFizKFkVxUFtSqa@bombadil.infradead.org/
* This is a patch set that replaces register_sysctl_table with register_sysctl
  https://lore.kernel.org/all/20230302204612.782387-1-mcgrof@kernel.org/
* Patch set to deprecate register_sysctl_paths()
  https://lore.kernel.org/all/20230302202826.776286-1-mcgrof@kernel.org/
* Here there is an explicit expectation for the removal of the sentinel element.
  https://lore.kernel.org/all/20230321130908.6972-1-frank.li@vivo.com
* The "ARRAY_SIZE" approach was mentioned (proposed?) in this thread
  https://lore.kernel.org/all/20220220060626.15885-1-tangmeng@uniontech.com

[3]
To measure the in memory savings apply this on top of this patchset.

"
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index c88854df0b62..e0073a627bac 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -976,6 +976,8 @@ 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);
+       // Counts additional sentinel used for each new dir.
+       printk("%ld sysctl saved mem kzalloc \n", sizeof(struct ctl_table));

        return new;
 }
@@ -1199,6 +1201,9 @@ static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table_
                link_name += len;
                link++;
        }
+       // Counts additional sentinel used for each new registration
+       //if ((head->ctl_table + head->ctl_table_size)->procname)
+               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
    echo $n
    accum=$(calc "$accum + $n")
done
echo $accum

[4]
add/remove: 0/0 grow/shrink: 0/21 up/down: 0/-2432 (-2432)
Function                                     old     new   delta
xpc_sys_xpc_hb                               192     128     -64
xpc_sys_xpc                                  128      64     -64
vrf_table                                    128      64     -64
ucma_ctl_table                               128      64     -64
tty_table                                    192     128     -64
sg_sysctls                                   128      64     -64
scsi_table                                   128      64     -64
random_table                                 448     384     -64
raid_table                                   192     128     -64
oa_table                                     192     128     -64
mac_hid_files                                256     192     -64
iwcm_ctl_table                               128      64     -64
ipmi_table                                   128      64     -64
hv_ctl_table                                 128      64     -64
hpet_table                                   128      64     -64
firmware_config_table                        192     128     -64
cdrom_table                                  448     384     -64
balloon_table                                128      64     -64
parport_sysctl_template                      912     720    -192
parport_default_sysctl_table                 584     136    -448
parport_device_sysctl_template               776     136    -640
Total: Before=429940038, After=429937606, chg -0.00%

[5]
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-64 (-64)
Function                                     old     new   delta
random_table                                 448     384     -64
Total: Before=1885527, After=1885463, chg -0.00%

[6] https://lore.kernel.org/all/20230913-jag-sysctl_remove_empty_elem_arch-v2-0-d1bd13a29bae@samsung.com/

Signed-off-by: Joel Granados <j.granados@samsung.com>

---

---
Joel Granados (15):
      cdrom: Remove now superfluous sentinel element from ctl_table array
      hpet: Remove now superfluous sentinel element from ctl_table array
      xen: Remove now superfluous sentinel element from ctl_table array
      tty: Remove now superfluous sentinel element from ctl_table array
      scsi: Remove now superfluous sentinel element from ctl_table array
      parport: Remove the now superfluous sentinel element from ctl_table array
      macintosh: Remove the now superfluous sentinel element from ctl_table array
      infiniband: Remove the now superfluous sentinel element from ctl_table array
      char-misc: Remove the now superfluous sentinel element from ctl_table array
      vrf: Remove the now superfluous sentinel element from ctl_table array
      sgi-xp: Remove the now superfluous sentinel element from ctl_table array
      fw loader: Remove the now superfluous sentinel element from ctl_table array
      raid: Remove now superfluous sentinel element from ctl_table array
      hyper-v/azure: Remove now superfluous sentinel element from ctl_table array
      intel drm: Remove now superfluous sentinel element from ctl_table array

 drivers/base/firmware_loader/fallback_table.c |  3 +-
 drivers/cdrom/cdrom.c                         |  3 +-
 drivers/char/hpet.c                           |  3 +-
 drivers/char/ipmi/ipmi_poweroff.c             |  3 +-
 drivers/char/random.c                         |  3 +-
 drivers/gpu/drm/i915/i915_perf.c              |  3 +-
 drivers/hv/hv_common.c                        |  3 +-
 drivers/infiniband/core/iwcm.c                |  3 +-
 drivers/infiniband/core/ucma.c                |  3 +-
 drivers/macintosh/mac_hid.c                   |  3 +-
 drivers/md/md.c                               |  3 +-
 drivers/misc/sgi-xp/xpc_main.c                |  6 ++--
 drivers/net/vrf.c                             |  3 +-
 drivers/parport/procfs.c                      | 42 ++++++++++++---------------
 drivers/scsi/scsi_sysctl.c                    |  3 +-
 drivers/scsi/sg.c                             |  3 +-
 drivers/tty/tty_io.c                          |  3 +-
 drivers/xen/balloon.c                         |  3 +-
 18 files changed, 36 insertions(+), 60 deletions(-)
---
base-commit: 0e945134b680040b8613e962f586d91b6d40292d
change-id: 20230927-jag-sysctl_remove_empty_elem_drivers-f034962a0d8c

Best regards,
-- 
Joel Granados <j.granados@samsung.com>
Re: [PATCH 00/15] sysctl: Remove sentinel elements from drivers
Posted by Christophe Leroy 7 months ago

Le 28/09/2023 à 15:21, Joel Granados via B4 Relay a écrit :
> From: Joel Granados <j.granados@samsung.com>

Automatic test fails on powerpc, see 
https://patchwork.ozlabs.org/project/linuxppc-dev/patch/20230928-jag-sysctl_remove_empty_elem_drivers-v1-15-e59120fca9f9@samsung.com/

Kernel attempted to read user page (1a111316) - exploit attempt? (uid: 0)
BUG: Unable to handle kernel data access on read at 0x1a111316
Faulting instruction address: 0xc0545338
Oops: Kernel access of bad area, sig: 11 [#1]
BE PAGE_SIZE=4K PowerPC 44x Platform
Modules linked in:
CPU: 0 PID: 1 Comm: swapper Not tainted 6.5.0-rc6-gdef13277bacb #1
Hardware name: amcc,bamboo 440GR Rev. B 0x422218d3 PowerPC 44x Platform
NIP:  c0545338 LR: c0548468 CTR: ffffffff
REGS: c084fae0 TRAP: 0300   Not tainted  (6.5.0-rc6-gdef13277bacb)
MSR:  00021000 <CE,ME>  CR: 84004288  XER: 00000000
DEAR: 1a111316 ESR: 00000000
GPR00: c0548468 c084fbd0 c0888000 c084fc99 00000000 c084fc7c 1a110316 
000affff
GPR08: ffffffff c084fd18 1a111316 04ffffff 22000282 00000000 c00027c0 
00000000
GPR16: 00000000 00000000 c0040000 c003d544 00000001 c003eb2c 096023d4 
00000000
GPR24: c0636502 c0636502 c084fc74 c0588510 c084fc68 c084fc7c c084fc99 
00000002
NIP [c0545338] string+0x78/0x148
LR [c0548468] vsnprintf+0x3d8/0x824
Call Trace:
[c084fbd0] [c084fc7c] 0xc084fc7c (unreliable)
[c084fbe0] [c0548468] vsnprintf+0x3d8/0x824
[c084fc30] [c0072dec] vprintk_store+0x17c/0x4c8
[c084fcc0] [c007322c] vprintk_emit+0xf4/0x2a0
[c084fd00] [c0073d04] _printk+0x60/0x88
[c084fd40] [c01ab63c] sysctl_err+0x78/0xa4
[c084fd80] [c01ab404] __register_sysctl_table+0x6a0/0x6c4
[c084fde0] [c06a585c] __register_sysctl_init+0x30/0x78
[c084fe00] [c06a8cc8] tty_init+0x44/0x168
[c084fe30] [c00023c4] do_one_initcall+0x64/0x2a0
[c084fea0] [c068f060] kernel_init_freeable+0x184/0x230
[c084fee0] [c00027e4] kernel_init+0x24/0x124
[c084ff00] [c000f1fc] ret_from_kernel_user_thread+0x14/0x1c
--- interrupt: 0 at 0x0
NIP:  00000000 LR: 00000000 CTR: 00000000
REGS: c084ff10 TRAP: 0000   Not tainted  (6.5.0-rc6-gdef13277bacb)
MSR:  00000000 <>  CR: 00000000  XER: 00000000

GPR00: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 
00000000
GPR08: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 
00000000
GPR16: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 
00000000
GPR24: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 
00000000
NIP [00000000] 0x0
LR [00000000] 0x0
--- interrupt: 0
Code: 91610008 90e1000c 4bffd0b5 80010014 38210010 7c0803a6 4e800020 
409d0008 99230000 38630001 38840001 4240ffd0 <7d2a20ae> 7f851840 
5528063e 2c080000
---[ end trace 0000000000000000 ]---

note: swapper[1] exited with irqs disabled
Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b


> 
> What?
> These commits remove the sentinel element (last empty element) from the
> sysctl arrays of all the files under the "drivers/" directory that use a
> sysctl array for registration. The merging of the preparation patches
> (in https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)
> to mainline allows us to just remove sentinel elements without changing
> behavior (more info here [1]).
> 
> These commits are part of a bigger set (here
> https://github.com/Joelgranados/linux/tree/tag/sysctl_remove_empty_elem_V4)
> that remove the ctl_table sentinel. Make the review process easier by
> chunking the commits into manageable pieces. Each chunk can be reviewed
> separately without noise from parallel sets.
> 
> Now that the architecture chunk has been mostly reviewed [6], we send
> the "drivers/" directory. Once this one is done, it will be follwed by
> "fs/*", "kernel/*", "net/*" and miscellaneous. The final set will remove
> the unneeded check for ->procname == NULL.
> 
> 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. I
> have consolidated some links that shed light on the history of this
> effort [2].
> 
> Testing:
> * Ran sysctl selftests (./tools/testing/selftests/sysctl/sysctl.sh)
> * Ran this through 0-day with no errors or warnings
> 
> Size saving after removing all sentinels:
>    These are the bytes that we save after removing all the sentinels
>    (this plus all the other chunks). I included them to get an idea of
>    how much memory we are talking about.
>      * bloat-o-meter:
>          - The "yesall" configuration results save 9158 bytes
>            https://lore.kernel.org/all/20230621091000.424843-1-j.granados@samsung.com/
>          - The "tiny" config + CONFIG_SYSCTL save 1215 bytes
>            https://lore.kernel.org/all/20230809105006.1198165-1-j.granados@samsung.com/
>      * memory usage:
>          In memory savings are measured to be 7296 bytes. (here is how to
>          measure [3])
> 
> Size saving after this patchset:
>      * bloat-o-meter
>          - The "yesall" config saves 2432 bytes [4]
>          - The "tiny" config saves 64 bytes [5]
>      * memory usage:
>          In this case there were no bytes saved because I do not have any
>          of the drivers in the patch. To measure it comment the printk in
>          `new_dir` and uncomment the if conditional in `new_links` [3].
> 
> Comments/feedback greatly appreciated
> 
> Best
> Joel
> 
> [1]
> We are able to remove a sentinel table without behavioral change by
> introducing a table_size argument in the same place where procname is
> checked for NULL. The idea is for it to keep stopping when it hits
> ->procname == NULL, while the sentinel is still present. And when the
> sentinel is removed, it will stop on the table_size. You can go to
> (https://lore.kernel.org/all/20230809105006.1198165-1-j.granados@samsung.com/)
> for more information.
> 
> [2]
> Links Related to the ctl_table sentinel removal:
> * Good summary from Luis sent with the "pull request" for the
>    preparation patches.
>    https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/
> * Another very good summary from Luis.
>    https://lore.kernel.org/all/ZMFizKFkVxUFtSqa@bombadil.infradead.org/
> * This is a patch set that replaces register_sysctl_table with register_sysctl
>    https://lore.kernel.org/all/20230302204612.782387-1-mcgrof@kernel.org/
> * Patch set to deprecate register_sysctl_paths()
>    https://lore.kernel.org/all/20230302202826.776286-1-mcgrof@kernel.org/
> * Here there is an explicit expectation for the removal of the sentinel element.
>    https://lore.kernel.org/all/20230321130908.6972-1-frank.li@vivo.com
> * The "ARRAY_SIZE" approach was mentioned (proposed?) in this thread
>    https://lore.kernel.org/all/20220220060626.15885-1-tangmeng@uniontech.com
> 
> [3]
> To measure the in memory savings apply this on top of this patchset.
> 
> "
> diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
> index c88854df0b62..e0073a627bac 100644
> --- a/fs/proc/proc_sysctl.c
> +++ b/fs/proc/proc_sysctl.c
> @@ -976,6 +976,8 @@ 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);
> +       // Counts additional sentinel used for each new dir.
> +       printk("%ld sysctl saved mem kzalloc \n", sizeof(struct ctl_table));
> 
>          return new;
>   }
> @@ -1199,6 +1201,9 @@ static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table_
>                  link_name += len;
>                  link++;
>          }
> +       // Counts additional sentinel used for each new registration
> +       //if ((head->ctl_table + head->ctl_table_size)->procname)
> +               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
>      echo $n
>      accum=$(calc "$accum + $n")
> done
> echo $accum
> 
> [4]
> add/remove: 0/0 grow/shrink: 0/21 up/down: 0/-2432 (-2432)
> Function                                     old     new   delta
> xpc_sys_xpc_hb                               192     128     -64
> xpc_sys_xpc                                  128      64     -64
> vrf_table                                    128      64     -64
> ucma_ctl_table                               128      64     -64
> tty_table                                    192     128     -64
> sg_sysctls                                   128      64     -64
> scsi_table                                   128      64     -64
> random_table                                 448     384     -64
> raid_table                                   192     128     -64
> oa_table                                     192     128     -64
> mac_hid_files                                256     192     -64
> iwcm_ctl_table                               128      64     -64
> ipmi_table                                   128      64     -64
> hv_ctl_table                                 128      64     -64
> hpet_table                                   128      64     -64
> firmware_config_table                        192     128     -64
> cdrom_table                                  448     384     -64
> balloon_table                                128      64     -64
> parport_sysctl_template                      912     720    -192
> parport_default_sysctl_table                 584     136    -448
> parport_device_sysctl_template               776     136    -640
> Total: Before=429940038, After=429937606, chg -0.00%
> 
> [5]
> add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-64 (-64)
> Function                                     old     new   delta
> random_table                                 448     384     -64
> Total: Before=1885527, After=1885463, chg -0.00%
> 
> [6] https://lore.kernel.org/all/20230913-jag-sysctl_remove_empty_elem_arch-v2-0-d1bd13a29bae@samsung.com/
> 
> Signed-off-by: Joel Granados <j.granados@samsung.com>
> 
> ---
> 
> ---
> Joel Granados (15):
>        cdrom: Remove now superfluous sentinel element from ctl_table array
>        hpet: Remove now superfluous sentinel element from ctl_table array
>        xen: Remove now superfluous sentinel element from ctl_table array
>        tty: Remove now superfluous sentinel element from ctl_table array
>        scsi: Remove now superfluous sentinel element from ctl_table array
>        parport: Remove the now superfluous sentinel element from ctl_table array
>        macintosh: Remove the now superfluous sentinel element from ctl_table array
>        infiniband: Remove the now superfluous sentinel element from ctl_table array
>        char-misc: Remove the now superfluous sentinel element from ctl_table array
>        vrf: Remove the now superfluous sentinel element from ctl_table array
>        sgi-xp: Remove the now superfluous sentinel element from ctl_table array
>        fw loader: Remove the now superfluous sentinel element from ctl_table array
>        raid: Remove now superfluous sentinel element from ctl_table array
>        hyper-v/azure: Remove now superfluous sentinel element from ctl_table array
>        intel drm: Remove now superfluous sentinel element from ctl_table array
> 
>   drivers/base/firmware_loader/fallback_table.c |  3 +-
>   drivers/cdrom/cdrom.c                         |  3 +-
>   drivers/char/hpet.c                           |  3 +-
>   drivers/char/ipmi/ipmi_poweroff.c             |  3 +-
>   drivers/char/random.c                         |  3 +-
>   drivers/gpu/drm/i915/i915_perf.c              |  3 +-
>   drivers/hv/hv_common.c                        |  3 +-
>   drivers/infiniband/core/iwcm.c                |  3 +-
>   drivers/infiniband/core/ucma.c                |  3 +-
>   drivers/macintosh/mac_hid.c                   |  3 +-
>   drivers/md/md.c                               |  3 +-
>   drivers/misc/sgi-xp/xpc_main.c                |  6 ++--
>   drivers/net/vrf.c                             |  3 +-
>   drivers/parport/procfs.c                      | 42 ++++++++++++---------------
>   drivers/scsi/scsi_sysctl.c                    |  3 +-
>   drivers/scsi/sg.c                             |  3 +-
>   drivers/tty/tty_io.c                          |  3 +-
>   drivers/xen/balloon.c                         |  3 +-
>   18 files changed, 36 insertions(+), 60 deletions(-)
> ---
> base-commit: 0e945134b680040b8613e962f586d91b6d40292d
> change-id: 20230927-jag-sysctl_remove_empty_elem_drivers-f034962a0d8c
> 
> Best regards,
Re: [PATCH 00/15] sysctl: Remove sentinel elements from drivers
Posted by Joel Granados 6 months, 4 weeks ago
On Thu, Sep 28, 2023 at 04:31:30PM +0000, Christophe Leroy wrote:
> 
> 
> Le 28/09/2023 à 15:21, Joel Granados via B4 Relay a écrit :
> > From: Joel Granados <j.granados@samsung.com>
> 
> Automatic test fails on powerpc, see 
> https://patchwork.ozlabs.org/project/linuxppc-dev/patch/20230928-jag-sysctl_remove_empty_elem_drivers-v1-15-e59120fca9f9@samsung.com/
From this I got to this URL
https://github.com/linuxppc/linux-snowpatch/actions/runs/6339718136/job/17221399242
and saw this message "sysctl table check failed: dev/tty/ No proc_handler".
This means that we hit the check for entry->proc_handler in
sysctl_check_table.

> 
> Kernel attempted to read user page (1a111316) - exploit attempt? (uid: 0)
> BUG: Unable to handle kernel data access on read at 0x1a111316
> Faulting instruction address: 0xc0545338
> Oops: Kernel access of bad area, sig: 11 [#1]
> BE PAGE_SIZE=4K PowerPC 44x Platform
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper Not tainted 6.5.0-rc6-gdef13277bacb #1
> Hardware name: amcc,bamboo 440GR Rev. B 0x422218d3 PowerPC 44x Platform
> NIP:  c0545338 LR: c0548468 CTR: ffffffff
> REGS: c084fae0 TRAP: 0300   Not tainted  (6.5.0-rc6-gdef13277bacb)
> MSR:  00021000 <CE,ME>  CR: 84004288  XER: 00000000
> DEAR: 1a111316 ESR: 00000000
> GPR00: c0548468 c084fbd0 c0888000 c084fc99 00000000 c084fc7c 1a110316 
> 000affff
> GPR08: ffffffff c084fd18 1a111316 04ffffff 22000282 00000000 c00027c0 
> 00000000
> GPR16: 00000000 00000000 c0040000 c003d544 00000001 c003eb2c 096023d4 
> 00000000
> GPR24: c0636502 c0636502 c084fc74 c0588510 c084fc68 c084fc7c c084fc99 
> 00000002
> NIP [c0545338] string+0x78/0x148
> LR [c0548468] vsnprintf+0x3d8/0x824
> Call Trace:
> [c084fbd0] [c084fc7c] 0xc084fc7c (unreliable)
> [c084fbe0] [c0548468] vsnprintf+0x3d8/0x824
> [c084fc30] [c0072dec] vprintk_store+0x17c/0x4c8
> [c084fcc0] [c007322c] vprintk_emit+0xf4/0x2a0
> [c084fd00] [c0073d04] _printk+0x60/0x88
> [c084fd40] [c01ab63c] sysctl_err+0x78/0xa4
> [c084fd80] [c01ab404] __register_sysctl_table+0x6a0/0x6c4
> [c084fde0] [c06a585c] __register_sysctl_init+0x30/0x78
> [c084fe00] [c06a8cc8] tty_init+0x44/0x168
> [c084fe30] [c00023c4] do_one_initcall+0x64/0x2a0
> [c084fea0] [c068f060] kernel_init_freeable+0x184/0x230
> [c084fee0] [c00027e4] kernel_init+0x24/0x124
> [c084ff00] [c000f1fc] ret_from_kernel_user_thread+0x14/0x1c
I followed this trace and proc_handler is correctly defined in tty_table
(struct ctl_table) in drivers/tty/tty_io.c:tty_init and there is not
path that changes these values.
Additionally, we then fail trying to print instead of continuing with
the initialization. My conjecture is that this might be due to something
different than tht sysctl register call.

Does this happen consistenly or is this just a one off issue?

To what branch are these patches being applied to?

I'm going to post my V2 and keep working on this issue if it pops up
again.

Thx for the report

Best

> --- interrupt: 0 at 0x0
> NIP:  00000000 LR: 00000000 CTR: 00000000
> REGS: c084ff10 TRAP: 0000   Not tainted  (6.5.0-rc6-gdef13277bacb)
> MSR:  00000000 <>  CR: 00000000  XER: 00000000
> 
> GPR00: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 
> 00000000
> GPR08: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 
> 00000000
> GPR16: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 
> 00000000
> GPR24: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 
> 00000000
> NIP [00000000] 0x0
> LR [00000000] 0x0
> --- interrupt: 0
> Code: 91610008 90e1000c 4bffd0b5 80010014 38210010 7c0803a6 4e800020 
> 409d0008 99230000 38630001 38840001 4240ffd0 <7d2a20ae> 7f851840 
> 5528063e 2c080000
> ---[ end trace 0000000000000000 ]---
> 
> note: swapper[1] exited with irqs disabled
> Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
> 
> 
> > 
> > What?
> > These commits remove the sentinel element (last empty element) from the
> > sysctl arrays of all the files under the "drivers/" directory that use a
> > sysctl array for registration. The merging of the preparation patches
> > (in https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)
> > to mainline allows us to just remove sentinel elements without changing
> > behavior (more info here [1]).
<--- snip --->
> >   drivers/macintosh/mac_hid.c                   |  3 +-
> >   drivers/md/md.c                               |  3 +-
> >   drivers/misc/sgi-xp/xpc_main.c                |  6 ++--
> >   drivers/net/vrf.c                             |  3 +-
> >   drivers/parport/procfs.c                      | 42 ++++++++++++---------------
> >   drivers/scsi/scsi_sysctl.c                    |  3 +-
> >   drivers/scsi/sg.c                             |  3 +-
> >   drivers/tty/tty_io.c                          |  3 +-
> >   drivers/xen/balloon.c                         |  3 +-
> >   18 files changed, 36 insertions(+), 60 deletions(-)
> > ---
> > base-commit: 0e945134b680040b8613e962f586d91b6d40292d
> > change-id: 20230927-jag-sysctl_remove_empty_elem_drivers-f034962a0d8c
> > 
> > Best regards,

-- 

Joel Granados
Re: [PATCH 00/15] sysctl: Remove sentinel elements from drivers
Posted by Christophe Leroy 6 months, 4 weeks ago

Le 02/10/2023 à 10:47, Joel Granados a écrit :
> On Thu, Sep 28, 2023 at 04:31:30PM +0000, Christophe Leroy wrote:

> I followed this trace and proc_handler is correctly defined in tty_table
> (struct ctl_table) in drivers/tty/tty_io.c:tty_init and there is not
> path that changes these values.
> Additionally, we then fail trying to print instead of continuing with
> the initialization. My conjecture is that this might be due to something
> different than tht sysctl register call.
> 
> Does this happen consistenly or is this just a one off issue?

Don't know.

> 
> To what branch are these patches being applied to?

As far as I understand from 
https://github.com/linuxppc/linux-snowpatch/commits/snowpatch/375319, 
it's being applied on 
https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/commit/?id=d774975


> 
> I'm going to post my V2 and keep working on this issue if it pops up
> again.
> 

Christophe
[PATCH 01/15] cdrom: Remove now superfluous sentinel element from ctl_table array
Posted by Joel Granados via B4 Relay 7 months ago
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 cdrom_table

Signed-off-by: Joel Granados <j.granados@samsung.com>
---
 drivers/cdrom/cdrom.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
index cc2839805983..451907ade389 100644
--- a/drivers/cdrom/cdrom.c
+++ b/drivers/cdrom/cdrom.c
@@ -3654,8 +3654,7 @@ static struct ctl_table cdrom_table[] = {
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= cdrom_sysctl_handler
-	},
-	{ }
+	}
 };
 static struct ctl_table_header *cdrom_sysctl_header;
 

-- 
2.30.2
Re: [PATCH 01/15] cdrom: Remove now superfluous sentinel element from ctl_table array
Posted by Greg Kroah-Hartman 7 months ago
On Thu, Sep 28, 2023 at 03:21:26PM +0200, 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/)
> 
> Remove sentinel element from cdrom_table
> 
> Signed-off-by: Joel Granados <j.granados@samsung.com>
> ---
>  drivers/cdrom/cdrom.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
> index cc2839805983..451907ade389 100644
> --- a/drivers/cdrom/cdrom.c
> +++ b/drivers/cdrom/cdrom.c
> @@ -3654,8 +3654,7 @@ static struct ctl_table cdrom_table[] = {
>  		.maxlen		= sizeof(int),
>  		.mode		= 0644,
>  		.proc_handler	= cdrom_sysctl_handler
> -	},
> -	{ }
> +	}

You should have the final entry as "}," so as to make any future
additions to the list to only contain that entry, that's long been the
kernel style for lists like this.

So your patches will just remove one line, not 2 and add 1, making it a
smaller diff.

thanks,

greg k-h
Re: [PATCH 01/15] cdrom: Remove now superfluous sentinel element from ctl_table array
Posted by Joel Granados 7 months ago
On Thu, Sep 28, 2023 at 03:36:55PM +0200, Greg Kroah-Hartman wrote:
> On Thu, Sep 28, 2023 at 03:21:26PM +0200, 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/)
> > 
> > Remove sentinel element from cdrom_table
> > 
> > Signed-off-by: Joel Granados <j.granados@samsung.com>
> > ---
> >  drivers/cdrom/cdrom.c | 3 +--
> >  1 file changed, 1 insertion(+), 2 deletions(-)
> > 
> > diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
> > index cc2839805983..451907ade389 100644
> > --- a/drivers/cdrom/cdrom.c
> > +++ b/drivers/cdrom/cdrom.c
> > @@ -3654,8 +3654,7 @@ static struct ctl_table cdrom_table[] = {
> >  		.maxlen		= sizeof(int),
> >  		.mode		= 0644,
> >  		.proc_handler	= cdrom_sysctl_handler
> > -	},
> > -	{ }
> > +	}
> 
> You should have the final entry as "}," so as to make any future
> additions to the list to only contain that entry, that's long been the
> kernel style for lists like this.
Will send a V2 with this included. Thx.

> 
> So your patches will just remove one line, not 2 and add 1, making it a
> smaller diff.
indeed.

> 
> thanks,
> 
> greg k-h

-- 

Joel Granados
Re: [PATCH 01/15] cdrom: Remove now superfluous sentinel element from ctl_table array
Posted by Phillip Potter 7 months ago
On Fri, Sep 29, 2023 at 02:17:30PM +0200, Joel Granados wrote:
> On Thu, Sep 28, 2023 at 03:36:55PM +0200, Greg Kroah-Hartman wrote:
> > On Thu, Sep 28, 2023 at 03:21:26PM +0200, 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/)
> > > 
> > > Remove sentinel element from cdrom_table
> > > 
> > > Signed-off-by: Joel Granados <j.granados@samsung.com>
> > > ---
> > >  drivers/cdrom/cdrom.c | 3 +--
> > >  1 file changed, 1 insertion(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
> > > index cc2839805983..451907ade389 100644
> > > --- a/drivers/cdrom/cdrom.c
> > > +++ b/drivers/cdrom/cdrom.c
> > > @@ -3654,8 +3654,7 @@ static struct ctl_table cdrom_table[] = {
> > >  		.maxlen		= sizeof(int),
> > >  		.mode		= 0644,
> > >  		.proc_handler	= cdrom_sysctl_handler
> > > -	},
> > > -	{ }
> > > +	}
> > 
> > You should have the final entry as "}," so as to make any future
> > additions to the list to only contain that entry, that's long been the
> > kernel style for lists like this.
> Will send a V2 with this included. Thx.
> 
> > 
> > So your patches will just remove one line, not 2 and add 1, making it a
> > smaller diff.
> indeed.
> 
> > 
> > thanks,
> > 
> > greg k-h
> 
> -- 
> 
> Joel Granados

Hi Joel,

Thank you for your patch. I look forward to seeing V2, and will be happy
to review it.

Regards,
Phil
Re: [PATCH 01/15] cdrom: Remove now superfluous sentinel element from ctl_table array
Posted by Joel Granados 6 months, 4 weeks ago
On Sat, Sep 30, 2023 at 05:52:17PM +0100, Phillip Potter wrote:
> On Fri, Sep 29, 2023 at 02:17:30PM +0200, Joel Granados wrote:
> > On Thu, Sep 28, 2023 at 03:36:55PM +0200, Greg Kroah-Hartman wrote:
> > > On Thu, Sep 28, 2023 at 03:21:26PM +0200, 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/)
> > > > 
> > > > Remove sentinel element from cdrom_table
> > > > 
> > > > Signed-off-by: Joel Granados <j.granados@samsung.com>
> > > > ---
> > > >  drivers/cdrom/cdrom.c | 3 +--
> > > >  1 file changed, 1 insertion(+), 2 deletions(-)
> > > > 
> > > > diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
> > > > index cc2839805983..451907ade389 100644
> > > > --- a/drivers/cdrom/cdrom.c
> > > > +++ b/drivers/cdrom/cdrom.c
> > > > @@ -3654,8 +3654,7 @@ static struct ctl_table cdrom_table[] = {
> > > >  		.maxlen		= sizeof(int),
> > > >  		.mode		= 0644,
> > > >  		.proc_handler	= cdrom_sysctl_handler
> > > > -	},
> > > > -	{ }
> > > > +	}
> > > 
> > > You should have the final entry as "}," so as to make any future
> > > additions to the list to only contain that entry, that's long been the
> > > kernel style for lists like this.
> > Will send a V2 with this included. Thx.
> > 
> > > 
> > > So your patches will just remove one line, not 2 and add 1, making it a
> > > smaller diff.
> > indeed.
> > 
> > > 
> > > thanks,
> > > 
> > > greg k-h
> > 
> > -- 
> > 
> > Joel Granados
> 
> Hi Joel,
> 
> Thank you for your patch. I look forward to seeing V2, and will be happy
> to review it.
Am following a reported oops. Once I straighten that out, I'll send out
a V2

Bet

> 
> Regards,
> Phil

-- 

Joel Granados
[PATCH 02/15] hpet: Remove now superfluous sentinel element from ctl_table array
Posted by Joel Granados via B4 Relay 7 months ago
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 the last empty element from hpet_table.

Signed-off-by: Joel Granados <j.granados@samsung.com>
---
 drivers/char/hpet.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/char/hpet.c b/drivers/char/hpet.c
index ee71376f174b..11f466fea5ed 100644
--- a/drivers/char/hpet.c
+++ b/drivers/char/hpet.c
@@ -727,8 +727,7 @@ static struct ctl_table hpet_table[] = {
 	 .maxlen = sizeof(int),
 	 .mode = 0644,
 	 .proc_handler = proc_dointvec,
-	 },
-	{}
+	}
 };
 
 static struct ctl_table_header *sysctl_header;

-- 
2.30.2
[PATCH 03/15] xen: Remove now superfluous sentinel element from ctl_table array
Posted by Joel Granados via B4 Relay 7 months ago
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 from balloon_table

Signed-off-by: Joel Granados <j.granados@samsung.com>
---
 drivers/xen/balloon.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 586a1673459e..091eb2931ac4 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -93,8 +93,7 @@ static struct ctl_table balloon_table[] = {
 		.proc_handler	= proc_dointvec_minmax,
 		.extra1         = SYSCTL_ZERO,
 		.extra2         = SYSCTL_ONE,
-	},
-	{ }
+	}
 };
 
 #else

-- 
2.30.2
Re: [PATCH 03/15] xen: Remove now superfluous sentinel element from ctl_table array
Posted by Juergen Gross 7 months ago
On 28.09.23 15:21, 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/)
> 
> Remove sentinel from balloon_table
> 
> Signed-off-by: Joel Granados <j.granados@samsung.com>

Acked-by: Juergen Gross <jgross@suse.com>


Juergen

[PATCH 04/15] tty: Remove now superfluous sentinel element from ctl_table array
Posted by Joel Granados via B4 Relay 7 months ago
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 from tty_table

Signed-off-by: Joel Granados <j.granados@samsung.com>
---
 drivers/tty/tty_io.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 8a94e5a43c6d..2f925dc54a20 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -3607,8 +3607,7 @@ static struct ctl_table tty_table[] = {
 		.proc_handler	= proc_dointvec,
 		.extra1		= SYSCTL_ZERO,
 		.extra2		= SYSCTL_ONE,
-	},
-	{ }
+	}
 };
 
 /*

-- 
2.30.2
Re: [PATCH 04/15] tty: Remove now superfluous sentinel element from ctl_table array
Posted by Jiri Slaby 6 months, 4 weeks ago
On 28. 09. 23, 15:21, 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/)
> 
> Remove sentinel from tty_table
> 
> Signed-off-by: Joel Granados <j.granados@samsung.com>
> ---
>   drivers/tty/tty_io.c | 3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
> index 8a94e5a43c6d..2f925dc54a20 100644
> --- a/drivers/tty/tty_io.c
> +++ b/drivers/tty/tty_io.c
> @@ -3607,8 +3607,7 @@ static struct ctl_table tty_table[] = {
>   		.proc_handler	= proc_dointvec,
>   		.extra1		= SYSCTL_ZERO,
>   		.extra2		= SYSCTL_ONE,
> -	},
> -	{ }
> +	}

Why to remove the comma? One would need to add one when adding a new entry?

thanks,
-- 
js
suse labs
Re: [PATCH 04/15] tty: Remove now superfluous sentinel element from ctl_table array
Posted by Christophe Leroy 6 months, 4 weeks ago

Le 02/10/2023 à 10:17, Jiri Slaby a écrit :
> On 28. 09. 23, 15:21, 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/)
>>
>> Remove sentinel from tty_table
>>
>> Signed-off-by: Joel Granados <j.granados@samsung.com>
>> ---
>>   drivers/tty/tty_io.c | 3 +--
>>   1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
>> index 8a94e5a43c6d..2f925dc54a20 100644
>> --- a/drivers/tty/tty_io.c
>> +++ b/drivers/tty/tty_io.c
>> @@ -3607,8 +3607,7 @@ static struct ctl_table tty_table[] = {
>>           .proc_handler    = proc_dointvec,
>>           .extra1        = SYSCTL_ZERO,
>>           .extra2        = SYSCTL_ONE,
>> -    },
>> -    { }
>> +    }
> 
> Why to remove the comma? One would need to add one when adding a new entry?

Does it make any difference at all ?

In one case you have:

@xxxx
  		something old,
  	},
+	{
+		something new,
+	},
  }

In the other case you have:

@xxxx
  		something old,
+ 	},
+	{
+		something new,
  	}
  }


Christophe
Re: [PATCH 04/15] tty: Remove now superfluous sentinel element from ctl_table array
Posted by Greg Kroah-Hartman 6 months, 4 weeks ago
On Mon, Oct 02, 2023 at 08:47:53AM +0000, Christophe Leroy wrote:
> 
> 
> Le 02/10/2023 à 10:17, Jiri Slaby a écrit :
> > On 28. 09. 23, 15:21, 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/)
> >>
> >> Remove sentinel from tty_table
> >>
> >> Signed-off-by: Joel Granados <j.granados@samsung.com>
> >> ---
> >>   drivers/tty/tty_io.c | 3 +--
> >>   1 file changed, 1 insertion(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
> >> index 8a94e5a43c6d..2f925dc54a20 100644
> >> --- a/drivers/tty/tty_io.c
> >> +++ b/drivers/tty/tty_io.c
> >> @@ -3607,8 +3607,7 @@ static struct ctl_table tty_table[] = {
> >>           .proc_handler    = proc_dointvec,
> >>           .extra1        = SYSCTL_ZERO,
> >>           .extra2        = SYSCTL_ONE,
> >> -    },
> >> -    { }
> >> +    }
> > 
> > Why to remove the comma? One would need to add one when adding a new entry?
> 
> Does it make any difference at all ?
> 
> In one case you have:
> 
> @xxxx
>   		something old,
>   	},
> +	{
> +		something new,
> +	},
>   }
> 
> In the other case you have:
> 
> @xxxx
>   		something old,
> + 	},
> +	{
> +		something new,
>   	}
>   }

Because that way it is obvious you are only touching the "something new"
lines and never have to touch the "something old" ones.

It's just a long-standing tradition in Linux, don't have an extra
character if you don't need it :)

thanks,

greg k-h
[PATCH 05/15] scsi: Remove now superfluous sentinel element from ctl_table array
Posted by Joel Granados via B4 Relay 7 months ago
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 from scsi_table and sg_sysctls.

Signed-off-by: Joel Granados <j.granados@samsung.com>
---
 drivers/scsi/scsi_sysctl.c | 3 +--
 drivers/scsi/sg.c          | 3 +--
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/scsi_sysctl.c b/drivers/scsi/scsi_sysctl.c
index 7f0914ea168f..c74da88b20d3 100644
--- a/drivers/scsi/scsi_sysctl.c
+++ b/drivers/scsi/scsi_sysctl.c
@@ -17,8 +17,7 @@ static struct ctl_table scsi_table[] = {
 	  .data		= &scsi_logging_level,
 	  .maxlen	= sizeof(scsi_logging_level),
 	  .mode		= 0644,
-	  .proc_handler	= proc_dointvec },
-	{ }
+	  .proc_handler	= proc_dointvec }
 };
 
 static struct ctl_table_header *scsi_table_header;
diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 0d8afffd1683..22a59c5e22eb 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -1649,8 +1649,7 @@ static struct ctl_table sg_sysctls[] = {
 		.maxlen		= sizeof(int),
 		.mode		= 0444,
 		.proc_handler	= proc_dointvec,
-	},
-	{}
+	}
 };
 
 static struct ctl_table_header *hdr;

-- 
2.30.2
[PATCH 06/15] parport: Remove the now superfluous sentinel element from ctl_table array
Posted by Joel Granados via B4 Relay 7 months ago
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 the unneeded ctl_tables that were used to register intermediate
parport directories; only the path is needed at this point. From
parport_device_sysctl_table we removed: devices_root_dir, port_dir,
parport_dir and dev_dir. From parport_default_sysctl_table we removed:
default_dir, parport_dir and dev_dir. Reduce the size by one of the
ctl_table arrays that were not removed

Assign different sizes to the vars array in parport_sysctl_table
depending on CONFIG_PARPORT_1284; this is necessary now that the sysctl
register function uses ARRAY_SIZE to calculate the elements within.
Remove the sentinel element from parport_sysctl_template,
parport_device_sysctl_table and parport_default_sysctl_table.

Signed-off-by: Joel Granados <j.granados@samsung.com>
---
 drivers/parport/procfs.c | 42 ++++++++++++++++++------------------------
 1 file changed, 18 insertions(+), 24 deletions(-)

diff --git a/drivers/parport/procfs.c b/drivers/parport/procfs.c
index 4e5b972c3e26..4118b3e52223 100644
--- a/drivers/parport/procfs.c
+++ b/drivers/parport/procfs.c
@@ -259,8 +259,12 @@ PARPORT_MAX_SPINTIME_VALUE;
 struct parport_sysctl_table {
 	struct ctl_table_header *port_header;
 	struct ctl_table_header *devices_header;
-	struct ctl_table vars[12];
-	struct ctl_table device_dir[2];
+#ifdef CONFIG_PARPORT_1284
+	struct ctl_table vars[10];
+#else
+	struct ctl_table vars[5];
+#endif /* IEEE 1284 support */
+	struct ctl_table device_dir[1];
 };
 
 static const struct parport_sysctl_table parport_sysctl_template = {
@@ -303,9 +307,9 @@ static const struct parport_sysctl_table parport_sysctl_template = {
 			.maxlen		= 0,
 			.mode		= 0444,
 			.proc_handler	= do_hardware_modes
-		},
+		}
 #ifdef CONFIG_PARPORT_1284
-		{
+		, {
 			.procname	= "autoprobe",
 			.data		= NULL,
 			.maxlen		= 0,
@@ -339,9 +343,8 @@ static const struct parport_sysctl_table parport_sysctl_template = {
 			.maxlen		= 0,
 			.mode		= 0444,
 			.proc_handler	= do_autoprobe
-		},
+		}
 #endif /* IEEE 1284 support */
-		{}
 	},
 	{
 		{
@@ -350,20 +353,15 @@ static const struct parport_sysctl_table parport_sysctl_template = {
 			.maxlen		= 0,
 			.mode		= 0444,
 			.proc_handler	= do_active_device
-		},
-		{}
+		}
 	},
 };
 
 struct parport_device_sysctl_table
 {
 	struct ctl_table_header *sysctl_header;
-	struct ctl_table vars[2];
-	struct ctl_table device_dir[2];
-	struct ctl_table devices_root_dir[2];
-	struct ctl_table port_dir[2];
-	struct ctl_table parport_dir[2];
-	struct ctl_table dev_dir[2];
+	struct ctl_table vars[1];
+	struct ctl_table device_dir[1];
 };
 
 static const struct parport_device_sysctl_table
@@ -378,8 +376,7 @@ parport_device_sysctl_template = {
 			.proc_handler	= proc_doulongvec_ms_jiffies_minmax,
 			.extra1		= (void*) &parport_min_timeslice_value,
 			.extra2		= (void*) &parport_max_timeslice_value
-		},
-		{}
+		}
 	},
 	{
 		{
@@ -387,18 +384,14 @@ parport_device_sysctl_template = {
 			.data		= NULL,
 			.maxlen		= 0,
 			.mode		= 0555,
-		},
-		{}
+		}
 	}
 };
 
 struct parport_default_sysctl_table
 {
 	struct ctl_table_header *sysctl_header;
-	struct ctl_table vars[3];
-	struct ctl_table default_dir[2];
-	struct ctl_table parport_dir[2];
-	struct ctl_table dev_dir[2];
+	struct ctl_table vars[2];
 };
 
 static struct parport_default_sysctl_table
@@ -422,8 +415,7 @@ parport_default_sysctl_table = {
 			.proc_handler	= proc_dointvec_minmax,
 			.extra1		= (void*) &parport_min_spintime_value,
 			.extra2		= (void*) &parport_max_spintime_value
-		},
-		{}
+		}
 	}
 };
 
@@ -443,7 +435,9 @@ int parport_proc_register(struct parport *port)
 	t->vars[0].data = &port->spintime;
 	for (i = 0; i < 5; i++) {
 		t->vars[i].extra1 = port;
+#ifdef CONFIG_PARPORT_1284
 		t->vars[5 + i].extra2 = &port->probe_info[i];
+#endif /* IEEE 1284 support */
 	}
 
 	port_name_len = strnlen(port->name, PARPORT_NAME_MAX_LEN);

-- 
2.30.2
[PATCH 07/15] macintosh: Remove the now superfluous sentinel element from ctl_table array
Posted by Joel Granados via B4 Relay 7 months ago
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 from mac_hid_files

Signed-off-by: Joel Granados <j.granados@samsung.com>
---
 drivers/macintosh/mac_hid.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/macintosh/mac_hid.c b/drivers/macintosh/mac_hid.c
index d8c4d5664145..5a228c7d9aeb 100644
--- a/drivers/macintosh/mac_hid.c
+++ b/drivers/macintosh/mac_hid.c
@@ -235,8 +235,7 @@ static struct ctl_table mac_hid_files[] = {
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
-	},
-	{ }
+	}
 };
 
 static struct ctl_table_header *mac_hid_sysctl_header;

-- 
2.30.2
[PATCH 08/15] infiniband: Remove the now superfluous sentinel element from ctl_table array
Posted by Joel Granados via B4 Relay 7 months ago
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 from iwcm_ctl_table and ucma_ctl_table

Signed-off-by: Joel Granados <j.granados@samsung.com>
---
 drivers/infiniband/core/iwcm.c | 3 +--
 drivers/infiniband/core/ucma.c | 3 +--
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/infiniband/core/iwcm.c b/drivers/infiniband/core/iwcm.c
index 2b47073c61a6..fefb9ae75789 100644
--- a/drivers/infiniband/core/iwcm.c
+++ b/drivers/infiniband/core/iwcm.c
@@ -110,8 +110,7 @@ static struct ctl_table iwcm_ctl_table[] = {
 		.maxlen		= sizeof(default_backlog),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
-	},
-	{ }
+	}
 };
 
 /*
diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
index bf42650f125b..92ad24ddf12a 100644
--- a/drivers/infiniband/core/ucma.c
+++ b/drivers/infiniband/core/ucma.c
@@ -70,8 +70,7 @@ static struct ctl_table ucma_ctl_table[] = {
 		.maxlen		= sizeof max_backlog,
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
-	},
-	{ }
+	}
 };
 
 struct ucma_file {

-- 
2.30.2
[PATCH 09/15] char-misc: Remove the now superfluous sentinel element from ctl_table array
Posted by Joel Granados via B4 Relay 7 months ago
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 from impi_table and random_table

Signed-off-by: Joel Granados <j.granados@samsung.com>
---
 drivers/char/ipmi/ipmi_poweroff.c | 3 +--
 drivers/char/random.c             | 3 +--
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/char/ipmi/ipmi_poweroff.c b/drivers/char/ipmi/ipmi_poweroff.c
index 870659d91db2..b65ab51bf9fa 100644
--- a/drivers/char/ipmi/ipmi_poweroff.c
+++ b/drivers/char/ipmi/ipmi_poweroff.c
@@ -655,8 +655,7 @@ static struct ctl_table ipmi_table[] = {
 	  .data		= &poweroff_powercycle,
 	  .maxlen	= sizeof(poweroff_powercycle),
 	  .mode		= 0644,
-	  .proc_handler	= proc_dointvec },
-	{ }
+	  .proc_handler	= proc_dointvec }
 };
 
 static struct ctl_table_header *ipmi_table_header;
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 3cb37760dfec..4040715cba19 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1682,8 +1682,7 @@ static struct ctl_table random_table[] = {
 		.procname	= "uuid",
 		.mode		= 0444,
 		.proc_handler	= proc_do_uuid,
-	},
-	{ }
+	}
 };
 
 /*

-- 
2.30.2