From owner-freebsd-toolchain@FreeBSD.ORG Sun Apr 29 23:39:26 2012 Return-Path: Delivered-To: toolchain@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 981FF106566B for ; Sun, 29 Apr 2012 23:39:26 +0000 (UTC) (envelope-from marcel@xcllnt.net) Received: from mail.xcllnt.net (mail.xcllnt.net [70.36.220.4]) by mx1.freebsd.org (Postfix) with ESMTP id 44F9A8FC0A for ; Sun, 29 Apr 2012 23:39:26 +0000 (UTC) Received: from dhcp-192-168-2-58.wifi.xcllnt.net (atm.xcllnt.net [70.36.220.6]) (authenticated bits=0) by mail.xcllnt.net (8.14.5/8.14.5) with ESMTP id q3TNdCDR069419 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NO); Sun, 29 Apr 2012 16:39:20 -0700 (PDT) (envelope-from marcel@xcllnt.net) Mime-Version: 1.0 (Apple Message framework v1257) Content-Type: text/plain; charset=us-ascii From: Marcel Moolenaar In-Reply-To: <20120429164300.GR2358@deviant.kiev.zoral.com.ua> Date: Sun, 29 Apr 2012 16:39:12 -0700 Content-Transfer-Encoding: quoted-printable Message-Id: <1D36CFB0-C4DA-4312-B200-58ABA0937977@xcllnt.net> References: <7B7A25D1-E99D-486A-B1CA-A5CFEA837B81@xcllnt.net> <20120429164300.GR2358@deviant.kiev.zoral.com.ua> To: Konstantin Belousov X-Mailer: Apple Mail (2.1257) Cc: toolchain@freebsd.org, Dmitry Mikulin Subject: Re: [GDB follow-fork] behavior change for wait() X-BeenThere: freebsd-toolchain@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Maintenance of FreeBSD's integrated toolchain List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 29 Apr 2012 23:39:26 -0000 On Apr 29, 2012, at 9:43 AM, Konstantin Belousov wrote: > On Fri, Apr 27, 2012 at 03:33:49PM -0700, Marcel Moolenaar wrote: >> Hi Dmitry, >>=20 >> I've been testing the follow-fork changes in GDB and ran into some = weird >> behavior. Without gdb, my test program (attached) prints something = like: >>=20 >> fbsdvm% ./fe=20 >> fe(41042): initial process. Doing fork & exec... >> fe(41043): child after fork. Doing exec... >> fe(41043): child after exec. Exiting... >> fe(41042): child 41043 exited with status 0 >>=20 >> In particular: the parent (pid=3D41042) calls wait(2) to reap the = child and >> the child exits with 0. >>=20 >> Under gdb, I see this: >>=20 >> fbsdvm% gdb ./fe >> GNU gdb 6.1.1 [FreeBSD] >> Copyright 2004 Free Software Foundation, Inc. >> GDB is free software, covered by the GNU General Public License, and = you are >> welcome to change it and/or distribute copies of it under certain = conditions. >> Type "show copying" to see the conditions. >> There is absolutely no warranty for GDB. Type "show warranty" for = details. >> This GDB was configured as "i386-marcel-freebsd"... >> (gdb) br main >> Breakpoint 1 at 0x80487b0: file fe.c, line 14. >> (gdb) run >> Starting program: /usr/home/marcel/fe=20 >>=20 >> Breakpoint 1, main (argc=3DError accessing memory address 0x1: Bad = address. >> ) at fe.c:14 >> 14 { >> (gdb) n >> main (argc=3D1, argv=3D0xbfbfebb4) at fe.c:19 >> 19 if (getenv("__FE_FORKED__") !=3D NULL) { >> (gdb) c >> Continuing. >> fe(41141): initial process. Doing fork & exec... >> [New process 41143] >> fe(41143): child after fork. Doing exec... >> fe(41143): child after exec. Exiting... >> fe(41141): wait(2) failed with error 10 (No child processes) >>=20 >> Program exited normally. >> (gdb)=20 >>=20 >> When stepping at least once, the inferior will not be able to = properly wait(2) >> for its child as it seems to have been reaped already. I suspect this = is done >> by the debugger -- unintentionally at least. >>=20 >> Have you seen this before? >=20 > How old is your kernel ? In particular, do you have > r232048+r232104+r232947+r232975+r233808+r233809 ? Yup: fbsdvm% uname -a FreeBSD fbsdvm 10.0-CURRENT FreeBSD 10.0-CURRENT #6 r234823: Sun Apr 29 = 16:18:07 PDT 2012 marcel@fbsdvm:/usr/obj/usr/src/sys/FBSDVM i386 This is off of the projects/nand branch, BTW: fbsdvm% svn info Path: . Working Copy Root Path: /usr/src URL: svn+ssh://svn.freebsd.org/base/projects/nand Repository Root: svn+ssh://svn.freebsd.org/base Repository UUID: ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f Revision: 234823 Node Kind: directory Schedule: normal Last Changed Author: gber Last Changed Rev: 234550 Last Changed Date: 2012-04-21 10:48:17 -0700 (Sat, 21 Apr 2012) Which is sync'd up to head @234446. --=20 Marcel Moolenaar marcel@xcllnt.net