From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 32233 invoked by alias); 15 Feb 2011 22:02:02 -0000 Mailing-List: contact archer-help@sourceware.org; run by ezmlm Sender: Precedence: bulk List-Post: List-Help: List-Subscribe: List-Id: Received: (qmail 32221 invoked by uid 22791); 15 Feb 2011 22:02:01 -0000 X-SWARE-Spam-Status: No, hits=-4.8 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_HI,SPF_HELO_PASS,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit From: Roland McGrath To: Jan Kratochvil X-Fcc: ~/Mail/utrace Cc: Oleg Nesterov , Project Archer Subject: Re: ptrace improvement: PTRACE_O_INHERIT In-Reply-To: Jan Kratochvil's message of Tuesday, 15 February 2011 22:43:33 +0100 <20110215214333.GA18086@host1.dyn.jankratochvil.net> References: <20110203223905.D0C77180081@magilla.sf.frob.com> <20110210195212.GA3868@redhat.com> <20110211192423.78FFC1802A2@magilla.sf.frob.com> <20110211203755.GA5367@redhat.com> <20110212005855.E764C1814A4@magilla.sf.frob.com> <20110212190253.GA31866@redhat.com> <20110214193052.3EC8D1814BA@magilla.sf.frob.com> <20110214193812.GA20765@redhat.com> <20110215003551.BC1EA1802A2@magilla.sf.frob.com> <20110215130805.GA30742@redhat.com> <20110215214333.GA18086@host1.dyn.jankratochvil.net> Message-Id: <20110215220153.470031806E0@magilla.sf.frob.com> Date: Tue, 15 Feb 2011 22:02:00 -0000 X-SW-Source: 2011-q1/txt/msg00056.txt.bz2 > Could PTRACE_ATTACH_NOSTOP+PTRACE_DETACH_NOSTOP? act on the whole PID at once > if PTRACE_O_THREAD_INHERIT is applied - already during PTRACE_ATTACH_NOSTOP? > It is a bit overloading the *_NOSTOP meaning but it is a new PTRACE_* op. This is an obviously desireable feature. I considered it when making my suggestions, but stopped short of suggesting it because I think it may have substantially difficult implementation issues in the kernel. It may well be that that detach-group is not really very hard to do at all (that probably being asynchronous detach, not requiring stopped tracees, and not supporting any parting-signal feature). Perhaps attach-group is also more tractable than I thought from a brief consideration of the implementation issues. Oleg will have to study it and give his opinions. It was my guess that even if it's pretty doable, the attach-group implementation will be sufficiently hairy that the kernel community would demand that we do some simpler incremental changes first before attempting it (such as what I proposed for ATTACH_NOSTOP, which eliminates the SIGSTOP and rolls in atomic option-setting). Thanks, Roland