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From: Konstantin Belousov <kostikbel@gmail.com>
To: Jilles Tjoelker <jilles@stack.nl>
Cc: FreeBSD Hackers <freebsd-hackers@freebsd.org>,
	Jonathan de Boyne Pollard
	<J.deBoynePollard-newsgroups@NTLWorld.com>,
	supervision@list.skarnet.org
Subject: Re: NOTE_TRACK, EVFILT_PROC, kqueue, and subreapers
Date: Mon, 12 Dec 2016 13:12:18 +0200	[thread overview]
Message-ID: <20161212111218.GB54029@kib.kiev.ua> (raw)
In-Reply-To: <20161211222328.GC17315@stack.nl>

On Sun, Dec 11, 2016 at 11:23:28PM +0100, Jilles Tjoelker wrote:
> On Sun, Dec 11, 2016 at 07:54:51PM +0200, Konstantin Belousov wrote:
> > On Sun, Dec 11, 2016 at 01:46:38PM +0100, Jilles Tjoelker wrote:
> > > As reported in https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=213928
> > > reapers do not receive SIGCHLD when inheriting zombies, although they do
> > > receive SIGCHLD when an inherited descendant process later terminates
> > > and are awakened when in a wait call for a matching process. This should
> > > probably be fixed.
> > I agree, in principle.  Could you update your tests/sys/kern/reaper.c to
> > include this scenario ?
> 
> I tested with the patch below. The new test case
> reaper_sigchld_child_first already passes and I have marked
> reaper_sigchld_grandchild_first as an expected timeout.
> 
> > Untested change to the kernel side is below.
> 
> > diff --git a/sys/kern/kern_exit.c b/sys/kern/kern_exit.c
> > index f4f453c3556..92899740eef 100644
> > --- a/sys/kern/kern_exit.c
> > +++ b/sys/kern/kern_exit.c
> > @@ -455,6 +455,12 @@ exit1(struct thread *td, int rval, int signo)
> >  
> >  		if (!(q->p_flag & P_TRACED)) {
> >  			proc_reparent(q, q->p_reaper);
> > +			if (q->p_state == PRS_ZOMBIE) {
> > +				PROC_LOCK(q->p_reaper);
> > +				pksignal(q->p_reaper, SIGCHLD, q->p_ksi);
> > +				wakeup(q->p_reaper);
> > +				PROC_UNLOCK(q->p_reaper);
> > +			}
> >  		} else {
> >  			/*
> >  			 * Traced processes are killed since their existence
> 
> This change makes reaper_sigchld_grandchild_first pass.
> 
> The wakeup added here is redundant with the one a few lines above:
>         if (q != NULL)          /* only need this if any child is S_ZOMB */
>                 wakeup(q->p_reaper);
I removed additional wakeup, it should be innocent.  Might be the better
change is to remove the lines you cited above and do wakeups inside the
loop after reparenting.  But I kept it that way for now.

> 
> This is also clear because reaper_wait_grandchild_first already passes.
> 
> Index: tests/sys/kern/reaper.c

Thank you, I verified that all tests pass with the patched kernel and
removed timeouts from your reaper_sigchld_*child_first new tests.
The kernel chunk is committed as r309886, please commit tests.
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  reply	other threads:[~2016-12-12 11:12 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20161102185444.GA911@protected.rcdrun.com>
     [not found] ` <20161201081829.GG1487@protected.rcdrun.com>
     [not found]   ` <20161201120531.374588b2@mydesk.domain.cxm>
     [not found]     ` <20161201172846.GP3428@protected.rcdrun.com>
     [not found]       ` <20161201124118.46778e2b@mydesk.domain.cxm>
     [not found]         ` <20161201174837.GR3428@protected.rcdrun.com>
     [not found]           ` <20161201125438.15230317@mydesk.domain.cxm>
     [not found]             ` <20161206104020.6b2ebb30@eto-mona.office.smartweb.sk>
     [not found]               ` <20161206102637.1ddd152a@mydesk.domain.cxm>
     [not found]                 ` <20161207155638.4b2dd629@eto-mona.office.smartweb.sk>
     [not found]                   ` <630ace89-e29b-d0d3-9f15-110d8dc3de08@NTLWorld.com>
     [not found]                     ` <20161208132842.5d7940bd@eto-mona.office.smartweb.sk>
2016-12-08 20:23                       ` Jonathan de Boyne Pollard
2016-12-11 12:46                         ` Jilles Tjoelker
2016-12-11 17:54                           ` Konstantin Belousov
2016-12-11 22:23                             ` Jilles Tjoelker
2016-12-12 11:12                               ` Konstantin Belousov [this message]
2016-12-13 12:39                           ` Jonathan de Boyne Pollard

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