From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F2954C433EF for ; Wed, 13 Oct 2021 00:09:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C871560041 for ; Wed, 13 Oct 2021 00:09:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235360AbhJMALC (ORCPT ); Tue, 12 Oct 2021 20:11:02 -0400 Received: from mail.kernel.org ([198.145.29.99]:58602 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234483AbhJMALA (ORCPT ); Tue, 12 Oct 2021 20:11:00 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id DF67D60041; Wed, 13 Oct 2021 00:08:57 +0000 (UTC) Date: Tue, 12 Oct 2021 20:08:56 -0400 From: Steven Rostedt To: Masami Hiramatsu Cc: LKML , Ingo Molnar , Andrew Morton , Tom Zanussi , Tzvetomir Stoyanov , Yordan Karadzhov Subject: Re: [PATCH v2] tracing: Fix event probe removal from dynamic events Message-ID: <20211012200856.6e5b8f28@gandalf.local.home> In-Reply-To: <20211013074226.d521cf9ddf378db20f77f043@kernel.org> References: <20211012081925.0e19cc4f@gandalf.local.home> <20211012233107.671725f6ec0316b3d0a9dd85@kernel.org> <20211012120310.2f742adb@gandalf.local.home> <20211013074226.d521cf9ddf378db20f77f043@kernel.org> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 13 Oct 2021 07:42:26 +0900 Masami Hiramatsu wrote: > On Tue, 12 Oct 2021 12:03:10 -0400 > Steven Rostedt wrote: > > > On Tue, 12 Oct 2021 23:31:07 +0900 > > Masami Hiramatsu wrote: > > > > > Hmm, this seems something wrong. Via dynamic_events interface, all the > > > events must be parsed equaly. If you have to pass the attached "system/event" > > > that's something wrong. The dynamic_events interface will accept > > > > > > -:[GROUP/]EVENT [optional arguments] > > > > > > Or > > > > > > !e:[GROUP/]EVENT [optional arguments] > > > > > > What did you expect other that these syntax? > > > > But there are non "optional arguments". > > > > To create the event probe, we need to send: > > > > e:[GROUP/]EVENT system/event [optional arguments] > > > > Where the "system/event" is what we attach to. Similar to adding a function > > or address to kprobes. Do you not need to add that for deleting a kprobe? > > No, since if the GROUP name is given, we can identify the event. > > And sorry. I misunderstood your patch, simply I mixed the group/event is > the name of group/event or the attached group/event. The GROUP/EVENT is the name of the created eprobe, my "system/event" is the name of the probe being attached. > > Actually, the dynamic_events delete command is something like wildcard > unless you specify the options. OK, so we need to update this a little bit more. But currently, it fails if you do: # echo 'e:hrstate timer/hrtimer_cancel state=+0x38($hrtimer):u8' >> dynamic_events # cat dynamic_events eprobes/hrstate timer.hrtimer_cancel state=+0x38($hrtimer):u8 # echo '-:eprobes/hrstate timer.hrtimer_cancel state=+0x38($hrtimer):u8' >> dynamic_events It will error out with "-EBUSY". It would make sense if we echo in exactly what is in dynamic_events with "-:" in front of it it, that it will remove it. But currently, it expects: # echo '-:eprobes/hrstate state=+0x38($hrtimer):u8' >> dynamic_events Which is completely wrong. > > > > > That is, if I create a kprobe with: > > > > p:myprobe schedule > dynamic_events > > > > To remove it, don't we need to have: > > > > -:myprobe schedule >> dynamic_events > > Yes, it is possible. But you can also do > > -:kprobes/myprobe >> dynamic_events > > So, the "schedule" trace point is optional. > > Anyway, let me comment on your patch again. OK, we can make it optional, but we need to fix it so that it also works. -- Steve