From owner-freebsd-toolchain@FreeBSD.ORG Sun Apr 29 16:43:11 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 727FE106564A for ; Sun, 29 Apr 2012 16:43:11 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from mail.zoral.com.ua (mx0.zoral.com.ua [91.193.166.200]) by mx1.freebsd.org (Postfix) with ESMTP id 0D7988FC15 for ; Sun, 29 Apr 2012 16:43:10 +0000 (UTC) Received: from skuns.kiev.zoral.com.ua (localhost [127.0.0.1]) by mail.zoral.com.ua (8.14.2/8.14.2) with ESMTP id q3TGh1iN068403; Sun, 29 Apr 2012 19:43:01 +0300 (EEST) (envelope-from kostikbel@gmail.com) Received: from deviant.kiev.zoral.com.ua (kostik@localhost [127.0.0.1]) by deviant.kiev.zoral.com.ua (8.14.5/8.14.5) with ESMTP id q3TGh1od002549; Sun, 29 Apr 2012 19:43:01 +0300 (EEST) (envelope-from kostikbel@gmail.com) Received: (from kostik@localhost) by deviant.kiev.zoral.com.ua (8.14.5/8.14.5/Submit) id q3TGh0L7002548; Sun, 29 Apr 2012 19:43:00 +0300 (EEST) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: deviant.kiev.zoral.com.ua: kostik set sender to kostikbel@gmail.com using -f Date: Sun, 29 Apr 2012 19:43:00 +0300 From: Konstantin Belousov To: Marcel Moolenaar Message-ID: <20120429164300.GR2358@deviant.kiev.zoral.com.ua> References: <7B7A25D1-E99D-486A-B1CA-A5CFEA837B81@xcllnt.net> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="BIyeO76nyr1ZoJNi" Content-Disposition: inline In-Reply-To: <7B7A25D1-E99D-486A-B1CA-A5CFEA837B81@xcllnt.net> User-Agent: Mutt/1.4.2.3i X-Virus-Scanned: clamav-milter 0.95.2 at skuns.kiev.zoral.com.ua X-Virus-Status: Clean X-Spam-Status: No, score=-4.0 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00 autolearn=ham version=3.2.5 X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on skuns.kiev.zoral.com.ua 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 16:43:11 -0000 --BIyeO76nyr1ZoJNi Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable 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 a= nd > 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 conditi= ons. > Type "show copying" to see the conditions. > There is absolutely no warranty for GDB. Type "show warranty" for detail= s. > 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 addres= s. > ) 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 wa= it(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? How old is your kernel ? In particular, do you have r232048+r232104+r232947+r232975+r233808+r233809 ? I cannot reproduce your issue on recent kernels and patched gdb. --BIyeO76nyr1ZoJNi Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (FreeBSD) iEYEARECAAYFAk+db5QACgkQC3+MBN1Mb4j98wCfWt9bOJBEZGjo5E8MD3YxfXxP I0EAn34ENM+jKxWbxhfmzjH2xn/MKDrh =S5ZC -----END PGP SIGNATURE----- --BIyeO76nyr1ZoJNi--