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In-Reply-To: <87o91tdy6r.fsf@oldenburg2.str.redhat.com>
From: Alistair Francis <alistair23@gmail.com>
Date: Fri, 19 Jul 2019 17:52:00 -0000
Message-ID: <CAKmqyKNfR3dL9xR-dNJnX8Qig+7NxWxcVipuf2k_oDBcYNR_TQ@mail.gmail.com>
Subject: Re: [RFC v3 03/23] sysdeps/wait: Use waitid if avaliable
To: Florian Weimer <fweimer@redhat.com>
Cc: Alistair Francis <alistair.francis@wdc.com>, GNU C Library <libc-alpha@sourceware.org>, 
	Arnd Bergmann <arnd@arndb.de>, Adhemerval Zanella <adhemerval.zanella@linaro.org>, 
	Palmer Dabbelt <palmer@sifive.com>, macro@wdc.com, Zong Li <zongbox@gmail.com>
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On Tue, Jul 16, 2019 at 10:31 PM Florian Weimer <fweimer@redhat.com> wrote:
>
> * Alistair Francis:
>
> > +#ifdef __NR_waitid
>
> I wonder if the condition should be
>
>   #ifndef __NR_wait4
>
> etc.  That would make it less risky for the existing architectures.

Seems fair, I have updated that.

>
> > +    case CLD_DUMPED:
> > +      *stat_loc =3D 0x80;
> > +    case CLD_KILLED:
> > +      *stat_loc |=3D infop.si_status;
> > +      break;
>
> The kernel does this (in kernel/exit.c):
>
>         status =3D (p->signal->flags & SIGNAL_GROUP_EXIT)
>                 ? p->signal->group_exit_code : p->exit_code;
>         wo->wo_stat =3D status;
> =E2=80=A6
>         if (infop) {
>                 if ((status & 0x7f) =3D=3D 0) {
>                         infop->cause =3D CLD_EXITED;
>                         infop->status =3D status >> 8;
>                 } else {
>                         infop->cause =3D (status & 0x80) ? CLD_DUMPED : C=
LD_KILLED;
>                         infop->status =3D status & 0x7f;
>                 }
>                 infop->pid =3D pid;
>                 infop->uid =3D uid;
>         }
>
> Therefore, I wonder if you need to propagate the lower bits from
> si_status for CLD_DUMPED, too.

We are propagating the bits due to a fall through in the switch
statement, I have added a comment to indicate that we are falling
through.

>
> For wait/wait3/waitpid, you could probably use the implementations for
> sysdeps/unix/bsd, layered on top of wait4.

I'm not sure what you mean here.

>
> The patch also needs some formatting tweaks regarding the placement of
> braces, and there are missing spaces before parentheses.

Yep, I have tried to fixup all the formatting issues.

Alistair

>
> Thanks,
> Florian