From owner-svn-src-head@FreeBSD.ORG  Fri Jun 17 21:44:13 2011
Return-Path: <owner-svn-src-head@FreeBSD.ORG>
Delivered-To: svn-src-head@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id C2765106566C;
	Fri, 17 Jun 2011 21:44:13 +0000 (UTC)
	(envelope-from obrien@FreeBSD.org)
Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:4f8:fff6::2c])
	by mx1.freebsd.org (Postfix) with ESMTP id B269E8FC0A;
	Fri, 17 Jun 2011 21:44:13 +0000 (UTC)
Received: from svn.freebsd.org (localhost [127.0.0.1])
	by svn.freebsd.org (8.14.4/8.14.4) with ESMTP id p5HLiDfo009297;
	Fri, 17 Jun 2011 21:44:13 GMT (envelope-from obrien@svn.freebsd.org)
Received: (from obrien@localhost)
	by svn.freebsd.org (8.14.4/8.14.4/Submit) id p5HLiDdP009295;
	Fri, 17 Jun 2011 21:44:13 GMT (envelope-from obrien@svn.freebsd.org)
Message-Id: <201106172144.p5HLiDdP009295@svn.freebsd.org>
From: "David E. O'Brien" <obrien@FreeBSD.org>
Date: Fri, 17 Jun 2011 21:44:13 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
	svn-src-head@freebsd.org
X-SVN-Group: head
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Cc: 
Subject: svn commit: r223212 - head/sys/kern
X-BeenThere: svn-src-head@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: SVN commit messages for the src tree for head/-current
	<svn-src-head.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-head>,
	<mailto:svn-src-head-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/svn-src-head>
List-Post: <mailto:svn-src-head@freebsd.org>
List-Help: <mailto:svn-src-head-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-head>,
	<mailto:svn-src-head-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Fri, 17 Jun 2011 21:44:13 -0000

Author: obrien
Date: Fri Jun 17 21:44:13 2011
New Revision: 223212
URL: http://svn.freebsd.org/changeset/base/223212

Log:
  Add comment from CSRG rev 7.27 (1992/06/23 19:56:55; author: mckusick)

Modified:
  head/sys/kern/sys_process.c

Modified: head/sys/kern/sys_process.c
==============================================================================
--- head/sys/kern/sys_process.c	Fri Jun 17 21:41:06 2011	(r223211)
+++ head/sys/kern/sys_process.c	Fri Jun 17 21:44:13 2011	(r223212)
@@ -829,6 +829,15 @@ kern_ptrace(struct thread *td, int req, 
 
 	case PT_ATTACH:
 		/* security check done above */
+		/*
+		 * It would be nice if the tracing relationship was separate
+		 * from the parent relationship but that would require
+		 * another set of links in the proc struct or for "wait"
+		 * to scan the entire proc table.  To make life easier,
+		 * we just re-parent the process we're trying to trace.
+		 * The old parent is remembered so we can put things back
+		 * on a "detach".
+		 */
 		p->p_flag |= P_TRACED;
 		p->p_oppid = p->p_pptr->p_pid;
 		if (p->p_pptr != td->td_proc) {