Date: Sun, 10 Jun 2001 11:45:40 -0700 (PDT) From: Matt Dillon <dillon@earth.backplane.com> To: Cejka Rudolf <cejkar@dcse.fee.vutbr.cz> Cc: David Malone <dwmalone@maths.tcd.ie>, Terry Lambert <tlambert2@mindspring.com>, hackers@FreeBSD.ORG Subject: signal(SIGCHLD, SIG_IGN) patch solving SUSv2 compatibility issue Message-ID: <200106101845.f5AIje014790@earth.backplane.com> References: <20010610183637.A73238@dcse.fee.vutbr.cz>
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:...
:
:sigemptyset(&sa.sa_mask);
:sa.sa_flags = 0;
:sa.sa_handler = SIG_IGN;
:sigaction(SIGCHLD, &sa, NULL);
:
:zombies are still created in FreeBSD, which is against SUSv2.
:
:My citation was quoted directly from sigaction() page and not
:from signal() page. Unfortunately, I do not have access to POSIX,
:so I do not know if it is specified in SUSv2 only or if it is
:specified in both SUSv2 and in POSIX. I'm afraid that it is in both.
:However I think, that FreeBSD wants to be SUSv2 compliant too, or not?
:...
I did some research and while I couldn't find the official POSIX
spec, I did read the SUSv2 spec carefully and I looked at a lot of
manual pages.
I believe your change is correct. We should disable zombie reaping
if SIGCHLD is set to SIG_IGN. This is, in fact, how most systems do
it. BSD is like the sickly child in some respects :-)
Your (revised) patch, which I have reproduced below along with a
little cleanup, looks correct. I compiled up a kernel with the
revised patch and tested it, and it seems to work as advertised.
I would say this should go into -current now. I would be happy to
do this, or David Malone can since he provided the fix to the original
patch.
I would also recommend that we MFC the patch to -stable after a few days.
It is highly unlikely to break anything. I suppose I could take the
heat for that :-) Every major forking program I've ever written has had
to set the sigaction flag *AND* set the signal handle to SIG_IGN to be
portable, and while I probably won't stop, it would be nice to know that
FreeBSD works both ways.
-Matt
Index: kern_sig.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/kern_sig.c,v
retrieving revision 1.72.2.6
diff -u -r1.72.2.6 kern_sig.c
--- kern_sig.c 2001/05/10 17:54:16 1.72.2.6
+++ kern_sig.c 2001/06/10 18:30:42
@@ -268,7 +268,9 @@
p->p_procsig->ps_flag |= PS_NOCLDSTOP;
else
p->p_procsig->ps_flag &= ~PS_NOCLDSTOP;
- if (act->sa_flags & SA_NOCLDWAIT) {
+ if ((act->sa_flags & SA_NOCLDWAIT) ||
+ ps->ps_sigact[_SIG_IDX(SIGCHLD)] == SIG_IGN
+ ) {
/*
* Paranoia: since SA_NOCLDWAIT is implemented
* by reparenting the dying child to PID 1 (and
@@ -279,8 +281,9 @@
p->p_procsig->ps_flag &= ~PS_NOCLDWAIT;
else
p->p_procsig->ps_flag |= PS_NOCLDWAIT;
- } else
+ } else {
p->p_procsig->ps_flag &= ~PS_NOCLDWAIT;
+ }
}
/*
* Set bit in p_sigignore for signals that are set to SIG_IGN,
@@ -438,6 +441,8 @@
* Reset no zombies if child dies flag as Solaris does.
*/
p->p_procsig->ps_flag &= ~PS_NOCLDWAIT;
+ if (ps->ps_sigact[_SIG_IDX(SIGCHLD)] == SIG_IGN)
+ ps->ps_sigact[_SIG_IDX(SIGCHLD)] = SIG_DFL;
}
/*
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