On 13.11.2016 02:39, Robert Elz wrote:
> Date: Sat, 12 Nov 2016 14:42:47 -0500
> From: "Christos Zoulas" <christos%netbsd.org@localhost>
> Message-ID: <20161112194247.37910FBA6%cvs.NetBSD.org@localhost>
>
> | PR/51624: Return the original parent for a traced process.
>
> Maybe the real bug here was that proc_reparent() is changing the
> child's p_ppid ?
>
> I can see no reason for that, and if it wasn't done, then p_ppid would
> be what is wanted by getppid() without needing kern_getppid() to
> do all that unwind logic (and assiated locting and unlocking to make
> it safe.)
>
> Aside from proc_reparent() the only weirdness I can see with p_ppid are
> in kern_proc.c in fill_eproc() and fill_kproc2(). They both use (and
> continue to use, so the results will be different for a process being
> traced, and the same process when not traced) p_pptr->p_pid rather than
> the simpler p_ppid but I am not sure why (nor what the clients of those
> functions are or what the info is used for, so I am not sure what is correct.)
>
> kre
>
It's also common to use kinfo_proc2 and extract data from there. There
is one field:
int32_t p_ppid; /* PID_T: Parent process id */
getppid(2) and p_ppid shall be the same.
I can add a test for it, comparing old parent identifier with p_ppid
from kinfo_proc2.
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