Re: [PATCH 7/9] sys: Replace hardcoding of -20 and 19 with MIN_NICE and MAX_NICE.

[Dongsheng Yang]

Hi Kees,

 On 02/12/2014 02:27 AM, Kees Cook wrote:
> On Mon, Feb 10, 2014 at 11:34 PM, Dongsheng Yang
> <yangds.fnst@xxxxxxxxxxxxxx> wrote:
> > Signed-off-by: Dongsheng Yang <yangds.fnst@xxxxxxxxxxxxxx>
> > cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > cc: Oleg Nesterov <oleg@xxxxxxxxxx>
> > cc: Robin Holt <holt@xxxxxxx>
> > cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
> > cc: Kees Cook <keescook@xxxxxxxxxxxx>
> > cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
> > cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
> > cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> > cc: Ingo Molnar <mingo@xxxxxxxxxx>
> > ---
> >   kernel/sys.c | 8 ++++----
> >   1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/kernel/sys.c b/kernel/sys.c
> > index c0a58be..adaeab6 100644
> > --- a/kernel/sys.c
> > +++ b/kernel/sys.c
> > @@ -174,10 +174,10 @@ SYSCALL_DEFINE3(setpriority, int, which, int, who, int, niceval)
> >
> >          /* normalize: avoid signed division (rounding problems) */
> >          error = -ESRCH;
> > -       if (niceval < -20)
> > -               niceval = -20;
> > -       if (niceval > 19)
> > -               niceval = 19;
> > +       if (niceval < MIN_NICE)
> > +               niceval = MIN_NICE;
> > +       if (niceval > MAX_NICE)
> > +               niceval = MAX_NICE;
> Good catch! I'm all for using names instead of numeric values,
> however, I wonder if it'd be more readable to use "clamp" instead?
>
> niceval = clamp(niceval, MIN_NICE, MAX_NICE);

Good suggestion! This patch here is just to replace the numeric values with
a name defined in prio.h. So I will send another patch to make it more 
readable
with clamp after the patch set here applied. Is this plan ok to you?

Thanx.
> -Kees
>
> >          rcu_read_lock();
> >          read_lock(&tasklist_lock);
> > --
> > 1.8.2.1

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