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

[Xiaoming Ni]

On 2020/5/15 16:06, Kees Cook wrote:
> 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?
Before  advance of the extraction patch, neg_one is only used in one 
file, does it seem to have no value for refactoring?


> >   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.
Thanks for guidance, your method is better

Thanks.
Xiaoming Ni