From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Mon, 13 Aug 2018 15:17:39 +0200 (CEST) Received: from mx3-rdu2.redhat.com ([66.187.233.73]:52006 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by eddie.linux-mips.org with ESMTP id S23994074AbeHMNReePqW9 (ORCPT ); Mon, 13 Aug 2018 15:17:34 +0200 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 4E79C8197039; Mon, 13 Aug 2018 13:17:28 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.34.27.30]) by smtp.corp.redhat.com (Postfix) with SMTP id DE62320389E0; Mon, 13 Aug 2018 13:17:24 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Mon, 13 Aug 2018 15:17:28 +0200 (CEST) Date: Mon, 13 Aug 2018 15:17:24 +0200 From: Oleg Nesterov To: Ravi Bangoria Cc: Song Liu , srikar@linux.vnet.ibm.com, Steven Rostedt , mhiramat@kernel.org, Peter Zijlstra , mingo@redhat.com, acme@kernel.org, alexander.shishkin@linux.intel.com, jolsa@redhat.com, namhyung@kernel.org, open list , ananth@linux.vnet.ibm.com, Alexis Berlemont , naveen.n.rao@linux.vnet.ibm.com, linux-arm-kernel@lists.infradead.org, linux-mips@linux-mips.org, linux@armlinux.org.uk, ralf@linux-mips.org, paul.burton@mips.com Subject: Re: [PATCH v8 3/6] Uprobes: Support SDT markers having reference count (semaphore) Message-ID: <20180813131723.GC28360@redhat.com> References: <20180809041856.1547-1-ravi.bangoria@linux.ibm.com> <20180809041856.1547-4-ravi.bangoria@linux.ibm.com> <95a1221e-aecc-42be-5239-a2c2429be176@linux.ibm.com> <20180813115019.GB28360@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.8]); Mon, 13 Aug 2018 13:17:28 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.8]); Mon, 13 Aug 2018 13:17:28 +0000 (UTC) for IP:'10.11.54.6' DOMAIN:'int-mx06.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'oleg@redhat.com' RCPT:'' Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 65564 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: oleg@redhat.com Precedence: bulk List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: linux-mips X-List-ID: linux-mips List-subscribe: List-owner: List-post: List-archive: X-list: linux-mips On 08/13, Ravi Bangoria wrote: > > > But damn, process creation (exec) is trivial. We could add a new uprobe_exec() > > hook and avoid delayed_uprobe_install() in uprobe_mmap(). > > I'm sorry. I didn't get this. Sorry for confusion... I meant, if only exec*( could race with _register(), we could add another uprobe hook which updates all (delayed) counters before return to user-mode. > > Afaics, the really problematic case is dlopen() which can race with _register() > > too, right? > > dlopen() should internally use mmap() right? So what is the problem here? Can > you please elaborate. What I tried to say is that we can't avoid uprobe_mmap()->delayed_uprobe_install() because dlopen() can race with _register() too, just like exec. Oleg. From mboxrd@z Thu Jan 1 00:00:00 1970 From: oleg@redhat.com (Oleg Nesterov) Date: Mon, 13 Aug 2018 15:17:24 +0200 Subject: [PATCH v8 3/6] Uprobes: Support SDT markers having reference count (semaphore) In-Reply-To: References: <20180809041856.1547-1-ravi.bangoria@linux.ibm.com> <20180809041856.1547-4-ravi.bangoria@linux.ibm.com> <95a1221e-aecc-42be-5239-a2c2429be176@linux.ibm.com> <20180813115019.GB28360@redhat.com> Message-ID: <20180813131723.GC28360@redhat.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 08/13, Ravi Bangoria wrote: > > > But damn, process creation (exec) is trivial. We could add a new uprobe_exec() > > hook and avoid delayed_uprobe_install() in uprobe_mmap(). > > I'm sorry. I didn't get this. Sorry for confusion... I meant, if only exec*( could race with _register(), we could add another uprobe hook which updates all (delayed) counters before return to user-mode. > > Afaics, the really problematic case is dlopen() which can race with _register() > > too, right? > > dlopen() should internally use mmap() right? So what is the problem here? Can > you please elaborate. What I tried to say is that we can't avoid uprobe_mmap()->delayed_uprobe_install() because dlopen() can race with _register() too, just like exec. Oleg.