commit 883136492c6d52d6acb644af581d338571968e09
Author: Matthias Rampke <matthias@rampke.de>
Date:   Tue Apr 17 23:33:16 2012 +0200

    kill zombies if the parent set SIG_IGN on SIGCHLD
    
    fix for http://bugs.dragonflybsd.org/issues/2349

diff --git a/sys/kern/kern_exit.c b/sys/kern/kern_exit.c
index f3ffb2b..3b5b780 100644
--- a/sys/kern/kern_exit.c
+++ b/sys/kern/kern_exit.c
@@ -534,11 +534,12 @@ exit1(int rv)
 	KNOTE(&p->p_klist, NOTE_EXIT);
 
 	/*
-	 * Notify parent that we're gone.  If parent has the PS_NOCLDWAIT
-	 * flag set, notify process 1 instead (and hope it will handle
-	 * this situation).
+         * Notify parent that we're gone.  If parent has the PS_NOCLDWAIT
+         * flag set, or if the handler is set to SIG_IGN, notify process 1
+         * instead (and hope it will handle this situation).
 	 */
-	if (p->p_pptr->p_sigacts->ps_flag & PS_NOCLDWAIT) {
+	if (p->p_pptr->p_sigacts->ps_flag &
+                (PS_NOCLDWAIT | PS_CLDSIGIGN)) {
 		struct proc *pp = p->p_pptr;
 
 		PHOLD(pp);
diff --git a/sys/kern/kern_sig.c b/sys/kern/kern_sig.c
index f3ce05c..fd905cd 100644
--- a/sys/kern/kern_sig.c
+++ b/sys/kern/kern_sig.c
@@ -321,6 +321,10 @@ kern_sigaction(int sig, struct sigaction *act, struct sigaction *oact)
 			} else {
 				p->p_sigacts->ps_flag &= ~PS_NOCLDWAIT;
 			}
+                        if (ps->ps_sigact[_SIG_IDX(SIGCHLD)] == SIG_IGN)
+                                ps->ps_flag |= PS_CLDSIGIGN;
+                        else
+                                ps->ps_flag &= ~PS_CLDSIGIGN;
 		}
 		/*
 		 * Set bit in p_sigignore for signals that are set to SIG_IGN,
@@ -433,7 +437,9 @@ execsigs(struct proc *p)
 	/*
 	 * Reset no zombies if child dies flag as Solaris does.
 	 */
-	p->p_sigacts->ps_flag &= ~PS_NOCLDWAIT;
+	p->p_sigacts->ps_flag &= ~(PS_NOCLDWAIT | PS_CLDSIGIGN);
+        if (ps->ps_sigact[_SIG_IDX(SIGCHLD)] == SIG_IGN)
+                ps->ps_sigact[_SIG_IDX(SIGCHLD)] = SIG_DFL;
 }
 
 /*
diff --git a/sys/sys/param.h b/sys/sys/param.h
index 17f8456..f15d0a0 100644
--- a/sys/sys/param.h
+++ b/sys/sys/param.h
@@ -90,9 +90,10 @@
  * 300100 - 3.1 master
  * 300101 - i4b (ISDN) removal
  * 300102 - <sys/ata.h> is now just a link of <sys/nata.h>
+ * 300103 - if SIG_IGN is set on SIGCHLD, do not keep zombie children
  */
 #undef __DragonFly_version
-#define __DragonFly_version 300102	/* propagated to newvers */
+#define __DragonFly_version 300103	/* propagated to newvers */
 
 #include <sys/_null.h>
 
diff --git a/sys/sys/proc.h b/sys/sys/proc.h
index ee829b4..2220707 100644
--- a/sys/sys/proc.h
+++ b/sys/sys/proc.h
@@ -112,6 +112,7 @@ struct	pgrp {
 
 #define	PS_NOCLDWAIT	0x0001	/* No zombies if child dies */
 #define	PS_NOCLDSTOP	0x0002	/* No SIGCHLD when children stop. */
+#define	PS_CLDSIGIGN    0x0004  /* The SIGCHLD handler is SIG_IGN. */
 
 /*
  * pargs, used to hold a copy of the command line, if it had a sane