From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752203AbdJDOIJ (ORCPT ); Wed, 4 Oct 2017 10:08:09 -0400 Received: from mail.kernel.org ([198.145.29.99]:55908 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751176AbdJDOII (ORCPT ); Wed, 4 Oct 2017 10:08:08 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BC7742188D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=mhiramat@kernel.org Date: Wed, 4 Oct 2017 23:08:04 +0900 From: Masami Hiramatsu To: Ingo Molnar Cc: mingo@redhat.com, x86@kernel.org, Steven Rostedt , linux-kernel@vger.kernel.org, Peter Zijlstra , Ananth N Mavinakayanahalli , Thomas Gleixner , "H . Peter Anvin" , "Paul E . McKenney" , Alexei Starovoitov , Alexei Starovoitov , Linus Torvalds Subject: Re: [BUGFIX PATCH] kprobes/x86: Remove IRQ disabling from jprobe handlers Message-Id: <20171004230804.9427341c928923a196c2a2b5@kernel.org> In-Reply-To: <20171004104101.nhtsotudcrh4d354@gmail.com> References: <20170930231251.emiuyrapdgzpcylp@inn> <150701508194.32266.14458959863314097305.stgit@devbox> <20171003093344.feh7gqa4aimsjwqv@gmail.com> <20171004002437.66c15c68ef662c0d9a458bef@kernel.org> <20171003171100.p535ul3wml4uhsow@gmail.com> <20171004151830.1e460cb7250b8741af0e2dbc@kernel.org> <20171004104101.nhtsotudcrh4d354@gmail.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 4 Oct 2017 12:41:01 +0200 Ingo Molnar wrote: > > * Masami Hiramatsu wrote: > > > Hmm, actually we can not disable jprobe, that has no separate Kconfig. > > So we need to introduce new kconfig for that. > > > > And, there are several network protocols using jprobe to trace events. > > (e.g. NET_DCCPPROBE and NET_TCPPROBE) > > I think they need to migrate to trace-event at first. > > > > So, how about below idea? > > > > 1. Introduce CONFIG_JPROBE_API which only separate jprobe general parts > > (no arch dependent code involves) and make it default n. > > 2. Mark break_handler and jprobe APIs deprecated so that no new user comes up. > > 3. migrate in-kernel jprobe user to trace-event or ftrace. > > (may take some time) > > So my suggestion would be to just return from register_jprobe() and don't register > anything. with CONFIG_JPROBE_API=n, is that right? > Yes, there are usecases of jprobes in the kernel, but they all look > pretty ancient and unused. Hmm, in that case, should we also remove those users? If we disable such way those features are just useless. > > So let's try this for -next and see whether anyone has a real usecase. And no > Kconfig and deprecation messages - those don't really work in practice - just > disable the functionality and force people to (trivially) modify the source if > they want to re-enable it. So you mean I don't have to change those usecases, just let them do. > > If this is fine for a single release then we can just remove it all: > > > 4. after that, we can completely remove jprobe which will be a series for > > all archs. (or just one big patch?) > > we want a series of patches - but that's for later. OK :) Thank you, > > Thanks, > > Ingo -- Masami Hiramatsu