Re: [patch 6/6] posix-cpu-timers: Make PID=0 and PID=self handling consistent

Thomas Gleixner
2019-09-23T14:17:17Z

On Mon, 23 Sep 2019, Frederic Weisbecker wrote:

> On Thu, Sep 05, 2019 at 02:03:45PM +0200, Thomas Gleixner wrote:
> > If the PID encoded into the clock id is 0 then the target is either the
> > calling thread itself or the process to which it belongs.
> >
> > If the current thread encodes its own PID on a process wide clock then
> > there is no reason not to treat it in the same way as the PID=0 case.
> >
> > Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> > ---
> > kernel/time/posix-cpu-timers.c | 9 ++++++++-
> > 1 file changed, 8 insertions(+), 1 deletion(-)
> >
> > --- a/kernel/time/posix-cpu-timers.c
> > +++ b/kernel/time/posix-cpu-timers.c
> > @@ -90,7 +90,14 @@ static struct task_struct *lookup_task(c
> >
> > } else {
> > /*
> > - * For processes require that p is group leader.
> > + * Timer is going to be attached to a process. If p is
> > + * current then treat it like the PID=0 case above.
> > + */
> > + if (p == current)
> > + return current->group_leader;
> > +
> > + /*
> > + * For foreign processes require that p is group leader.
> > */
> > if (!has_group_leader_pid(p))
> > return NULL;
>
> So, right after you should have that:
>
> if (same_thread_group(p, current))
> return p;
>
> Which I suggested to convert as:
>
> if (p == current)
> return p;

Indeed :)