linux-kernel - Re: [PATCH v2 03/14] sysctl: Add ctl_table_size to ctl_table

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Message-ID: <ZMf9vZpGE98oM9W2@kernel.org>
Date:   Mon, 31 Jul 2023 20:30:21 +0200
From:   Simon Horman <horms@...nel.org>
To:     Joel Granados <joel.granados@...il.com>
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        Joel Granados <j.granados@...sung.com>
Subject: Re: [PATCH v2 03/14] sysctl: Add ctl_table_size to ctl_table_header

On Mon, Jul 31, 2023 at 09:17:17AM +0200, Joel Granados wrote:
> The new ctl_table_size element will hold the size of the ctl_table
> arrays contained in the ctl_table_header. This value should eventually
> be passed by the callers to the sysctl register infrastructure. And
> while this commit introduces the variable, it does not set nor use it
> because that requires case by case considerations for each caller.
> 
> It provides two important things: (1) A place to put the
> result of the ctl_table array calculation when it gets introduced for
> each caller. And (2) the size that will be used as the additional
> stopping criteria in the list_for_each_table_entry macro (to be added
> when all the callers are migrated)
> 
> Signed-off-by: Joel Granados <j.granados@...sung.com>
> ---
>  include/linux/sysctl.h | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
> index 59d451f455bf..33252ad58ebe 100644
> --- a/include/linux/sysctl.h
> +++ b/include/linux/sysctl.h
> @@ -159,12 +159,22 @@ struct ctl_node {
>  	struct ctl_table_header *header;
>  };
>  
> -/* struct ctl_table_header is used to maintain dynamic lists of
> -   struct ctl_table trees. */
> +/**
> + * struct ctl_table_header - maintains dynamic lists of struct ctl_table trees
> + * @ctl_table: pointer to the first element in ctl_table array
> + * @ctl_table_size: number of elements pointed by @ctl_table
> + * @used: The entry will never be touched when equal to 0.
> + * @count: Upped every time something is added to @inodes and downed every time
> + *         something is removed from inodes
> + * @nreg: When nreg drops to 0 the ctl_table_header will be unregistered.
> + * @rcu: Delays the freeing of the inode. Introduced with "unfuck proc_sysctl ->d_compare()"
> + *
> + */

Hi Joel,

Please consider also adding kernel doc entries for the other fields of
struct ctl_table_header. According to ./scripts/kernel-doc -none
they are:

  unregistering
  ctl_table_arg
  root
  set
  parent
  node
  inodes


>  struct ctl_table_header {
>  	union {
>  		struct {
>  			struct ctl_table *ctl_table;
> +			int ctl_table_size;
>  			int used;
>  			int count;
>  			int nreg;
> -- 
> 2.30.2
>