From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with ESMTP id 98BFC8D0039 for ; Fri, 18 Mar 2011 14:59:56 -0400 (EDT) Received: from d01dlp02.pok.ibm.com (d01dlp02.pok.ibm.com [9.56.224.85]) by e3.ny.us.ibm.com (8.14.4/8.13.1) with ESMTP id p2IIdPnr018438 for ; Fri, 18 Mar 2011 14:39:29 -0400 Received: from d01relay05.pok.ibm.com (d01relay05.pok.ibm.com [9.56.227.237]) by d01dlp02.pok.ibm.com (Postfix) with ESMTP id D6C3E6E8036 for ; Fri, 18 Mar 2011 14:59:54 -0400 (EDT) Received: from d01av04.pok.ibm.com (d01av04.pok.ibm.com [9.56.224.64]) by d01relay05.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p2IIxsxe231508 for ; Fri, 18 Mar 2011 14:59:54 -0400 Received: from d01av04.pok.ibm.com (loopback [127.0.0.1]) by d01av04.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p2IIxrG0018212 for ; Fri, 18 Mar 2011 14:59:54 -0400 Date: Sat, 19 Mar 2011 00:23:14 +0530 From: Srikar Dronamraju Subject: Re: [PATCH v2 2.6.38-rc8-tip 5/20] 5: Uprobes: register/unregister probes. Message-ID: <20110318185314.GB24048@linux.vnet.ibm.com> Reply-To: Srikar Dronamraju References: <20110314133403.27435.7901.sendpatchset@localhost6.localdomain6> <20110314133454.27435.81020.sendpatchset@localhost6.localdomain6> <20110315171536.GA24254@linux.vnet.ibm.com> <1300211262.9910.295.camel@gandalf.stny.rr.com> <1300211411.2203.290.camel@twins> <20110315180423.GA10429@linux.vnet.ibm.com> <1300212949.2203.324.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <1300212949.2203.324.camel@twins> Sender: owner-linux-mm@kvack.org List-ID: To: Peter Zijlstra Cc: Steven Rostedt , Thomas Gleixner , Ingo Molnar , Linux-mm , Arnaldo Carvalho de Melo , Linus Torvalds , Christoph Hellwig , Masami Hiramatsu , Ananth N Mavinakayanahalli , Oleg Nesterov , LKML , SystemTap , Jim Keniston , Roland McGrath , Andi Kleen , Andrew Morton , "Paul E. McKenney" > > > > One of the install_uprobe could be failing because the process was > > almost exiting, something like there was no mm->owner. Also lets > > assume that the first few install_uprobes go thro and the last > > install_uprobe fails. There could be breakpoint hits corresponding to > > the already installed uprobes that get displayed. i.e all > > breakpoint hits from the first install_uprobe to the time we detect a > > failed a install_uprobe and revert all inserted breakpoints will be > > shown as being captured. > > I think you can gracefully deal with the exit case and simply ignore > that one. But you cannot let arbitrary installs fail and still report > success, that gives very weak and nearly useless semantics. If there are more than one instance of a process running and if one instance of a process has a probe thro ptrace, install_uprobe would fail for that process with -EEXIST since we dont want to probe locations that have breakpoints already. Should we then act similar to the exit case, do we also deal gracefully? -- Thanks and Regards Srikar -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org