Re: [PATCH 2/4] proc/sysctl: add shared variables -1

[Kees Cook]

On Fri, May 15, 2020 at 12:33:42PM +0800, Xiaoming Ni wrote:
> Add the shared variable SYSCTL_NEG_ONE to replace the variable neg_one
> used in both sysctl_writes_strict and hung_task_warnings.
> 
> Signed-off-by: Xiaoming Ni <nixiaoming@xxxxxxxxxx>
> ---
>  fs/proc/proc_sysctl.c     | 2 +-
>  include/linux/sysctl.h    | 1 +
>  kernel/hung_task_sysctl.c | 3 +--
>  kernel/sysctl.c           | 3 +--

How about doing this refactoring in advance of the extraction patch?

>  4 files changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
> index b6f5d45..acae1fa 100644
> --- a/fs/proc/proc_sysctl.c
> +++ b/fs/proc/proc_sysctl.c
> @@ -23,7 +23,7 @@
>  static const struct inode_operations proc_sys_dir_operations;
>  
>  /* shared constants to be used in various sysctls */
> -const int sysctl_vals[] = { 0, 1, INT_MAX };
> +const int sysctl_vals[] = { 0, 1, INT_MAX, -1 };
>  EXPORT_SYMBOL(sysctl_vals);
>  
>  /* Support for permanently empty directories */
> diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
> index 02fa844..6d741d6 100644
> --- a/include/linux/sysctl.h
> +++ b/include/linux/sysctl.h
> @@ -41,6 +41,7 @@
>  #define SYSCTL_ZERO	((void *)&sysctl_vals[0])
>  #define SYSCTL_ONE	((void *)&sysctl_vals[1])
>  #define SYSCTL_INT_MAX	((void *)&sysctl_vals[2])
> +#define SYSCTL_NEG_ONE	((void *)&sysctl_vals[3])

Nit: let's keep these value-ordered? i.e. -1, 0, 1, INT_MAX.

-- 
Kees Cook