Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752878AbaF3Lw3 (ORCPT ); Mon, 30 Jun 2014 07:52:29 -0400 Received: from mail9.hitachi.co.jp ([133.145.228.44]:33595 "EHLO mail9.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752676AbaF3Lw2 (ORCPT ); Mon, 30 Jun 2014 07:52:28 -0400 Message-ID: <53B14F75.2040307@hitachi.com> Date: Mon, 30 Jun 2014 20:52:21 +0900 From: Masami Hiramatsu Organization: Hitachi, Ltd., Japan User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:13.0) Gecko/20120614 Thunderbird/13.0.1 MIME-Version: 1.0 To: Oleg Nesterov Cc: Steven Rostedt , Namhyung Kim , Srikar Dronamraju , Tom Zanussi , "zhangwei(Jovi)" , linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/4] tracing/uprobes: Revert "Support mix of ftrace and perf" References: <20140627170136.GA18319@redhat.com> In-Reply-To: <20140627170136.GA18319@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (2014/06/28 2:01), Oleg Nesterov wrote: > This reverts commit 43fe98913c9f67e3b523615ee3316f9520a623e0. > > This patch is very wrong. Firstly, this change leads to unbalanced > uprobe_unregister(). Just for example, > > # perf probe -x /lib/libc.so.6 syscall > # echo 1 >> /sys/kernel/debug/tracing/events/probe_libc/enable > # perf record -e probe_libc:syscall whatever > > after that uprobe is dead (unregistered) but the user of ftrace/perf > can't know this, and it looks as if nobody hits this probe. > > This would be easy to fix, but there are other reasons why it is not > simple to mix ftrace and perf. If nothing else, they can't share the > same ->consumer.filter. This is fixable too, but probably we need to > fix the poorly designed uprobe_register() interface first. At least > "register" and "apply" should be clearly separated. Hm, it should be a uprobes original issue. it's different from kprobes. Reviewed-by: Masami Hiramatsu Thank you, > > Cc: stable@vger.kernel.org # v3.14 > Signed-off-by: Oleg Nesterov > --- > kernel/trace/trace_uprobe.c | 9 ++++++++- > 1 files changed, 8 insertions(+), 1 deletions(-) > > diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c > index 04fdb5d..08e7970 100644 > --- a/kernel/trace/trace_uprobe.c > +++ b/kernel/trace/trace_uprobe.c > @@ -893,6 +893,9 @@ probe_event_enable(struct trace_uprobe *tu, struct ftrace_event_file *file, > int ret; > > if (file) { > + if (tu->tp.flags & TP_FLAG_PROFILE) > + return -EINTR; > + > link = kmalloc(sizeof(*link), GFP_KERNEL); > if (!link) > return -ENOMEM; > @@ -901,8 +904,12 @@ probe_event_enable(struct trace_uprobe *tu, struct ftrace_event_file *file, > list_add_tail_rcu(&link->list, &tu->tp.files); > > tu->tp.flags |= TP_FLAG_TRACE; > - } else > + } else { > + if (tu->tp.flags & TP_FLAG_TRACE) > + return -EINTR; > + > tu->tp.flags |= TP_FLAG_PROFILE; > + } > > ret = uprobe_buffer_enable(); > if (ret < 0) > -- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Research Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/