From owner-svn-src-head@FreeBSD.ORG Tue Aug 26 21:24:01 2014 Return-Path: Delivered-To: svn-src-head@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 6742AF4D; Tue, 26 Aug 2014 21:24:01 +0000 (UTC) Received: from bigwig.baldwin.cx (bigwig.baldwin.cx [IPv6:2001:470:1f11:75::1]) (using TLSv1 with cipher DHE-RSA-CAMELLIA256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 396AA3FD9; Tue, 26 Aug 2014 21:24:01 +0000 (UTC) Received: from jhbbsd.localnet (unknown [209.249.190.124]) by bigwig.baldwin.cx (Postfix) with ESMTPSA id A3F60B94A; Tue, 26 Aug 2014 17:23:59 -0400 (EDT) From: John Baldwin To: "John-Mark Gurney" Subject: Re: svn commit: r270444 - in head/sys: kern sys Date: Tue, 26 Aug 2014 17:23:10 -0400 User-Agent: KMail/1.13.5 (FreeBSD/8.4-CBSD-20140415; KDE/4.5.5; amd64; ; ) References: <201408240904.s7O949sI083660@svn.freebsd.org> <201408261509.26815.jhb@freebsd.org> <20140826193210.GL71691@funkthat.com> In-Reply-To: <20140826193210.GL71691@funkthat.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201408261723.10854.jhb@freebsd.org> X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.2.7 (bigwig.baldwin.cx); Tue, 26 Aug 2014 17:23:59 -0400 (EDT) Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, Mateusz Guzik , src-committers@freebsd.org, Mateusz Guzik X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 26 Aug 2014 21:24:01 -0000 On Tuesday, August 26, 2014 3:32:10 pm John-Mark Gurney wrote: > John Baldwin wrote this message on Tue, Aug 26, 2014 at 15:09 -0400: > > On Monday, August 25, 2014 6:30:34 pm John-Mark Gurney wrote: > > > John Baldwin wrote this message on Mon, Aug 25, 2014 at 13:35 -0400: > > > > On Monday, August 25, 2014 07:02:41 PM Mateusz Guzik wrote: > > > > > On Mon, Aug 25, 2014 at 10:23:19AM -0400, John Baldwin wrote: > > > > > > On Sunday, August 24, 2014 09:04:09 AM Mateusz Guzik wrote: > > > > > > > Author: mjg > > > > > > > Date: Sun Aug 24 09:04:09 2014 > > > > > > > New Revision: 270444 > > > > > > > URL: http://svnweb.freebsd.org/changeset/base/270444 > > > > > > > > > > > > > > Log: > > > > > > > Fix getppid for traced processes. > > > > > > > > > > > > > > Traced processes always have the tracer set as the parent. > > > > > > > Utilize proc_realparent to obtain the right process when needed. > > > > > > > > > > > > Are you sure this won't break things? I know of several applications that > > > > > > expect a debugger to be the parent when attached and change behavior as a > > > > > > result (e.g. inserting a breakpoint on an assertion failure rather than > > > > > > generating a core). > > > > > > > > > > Well, this is what linux and solaris do. > > > > > > > > Interesting. > > > > > > > > > I don't feel strongly about this change. If you really want I'm happy to > > > > > revert. > > > > > > > > In general I'd like to someday have the debugger-debuggee relationship not > > > > override parent-child and this is a step in that direction. However, this > > > > will break existing applications, so this needs to be clearly documented in > > > > the release notes. In addition, we should probably advertise how a process > > > > can correctly determine if it is being run under a debugger (right now you can > > > > do 'getppid()' and use strcmp or strstr on the p_comm of that pid so you can > > > > do different things for "gdb" vs "gcore", etc. so just checking P_TRACED from > > > > kinfo_proc wouldn't be equivalent in functionality) > > > > > > But what about when you attach gdb to a running process... That > > > doesn't magicly make the now debugged process a child of gdb does it? > > > > % cat hello.c > > #include > > > > int > > main() > > { > > printf("hello world\n"); > > (void)getchar(); > > return (0); > > } > > % cc -g hello.c -o hello > > % ./hello > > hello world > > load: 9.81 cmd: hello 42599 [ttyin] 1.67r 0.00u 0.00s 0% 1056k > > > > < different window > > > > > % ps -O ppid -p `pgrep hello` > > PID PPID TT STAT TIME COMMAND > > 42599 5340 16 I+ 0:00.00 ./hello > > % gdb hello `pgrep hello` > > GNU gdb 6.1.1 [FreeBSD] > > ... > > (gdb) > > Suspended > > % ps -O ppid -p `pgrep hello` > > PID PPID TT STAT TIME COMMAND > > 42599 45079 16 TX+ 0:00.00 ./hello > > Wow, learn something new every day... > > But doesn't that break apps that use getppid to signal their parent > that forked them? Until mjg@'s commit, yes. It's been that way in FreeBSD at least for as long as I can remember. Certainly back to 4.x. -- John Baldwin