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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 74101C433EF for ; Thu, 13 Jan 2022 21:58:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236302AbiAMV6n (ORCPT ); Thu, 13 Jan 2022 16:58:43 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53506 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232985AbiAMV6l (ORCPT ); Thu, 13 Jan 2022 16:58:41 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 225FEC061574 for ; Thu, 13 Jan 2022 13:58:41 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id E0AB2B822C8 for ; Thu, 13 Jan 2022 21:58:39 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 38428C36AE3; Thu, 13 Jan 2022 21:58:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1642111118; bh=fvJjT8tvooCZLW7hRAzPYYagFNBEQaCwtqOS9vG6ws0=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=oC3ZFWniDyymw+N0lNIzQdymKVopt1ZZiuKg/Wj5elYyhcbQoQJipwWzfa3nNevhw +5hZYDxkcWMziawX+pq3fY/HEd5wx0VTfgymHjLSow87oUMB3thHpGwb+wOIoMwt5B KPbka/Spvnjgz6CINZOxl0fS49bHxOR0GpbGfAT+frBRP0D5HpEI4hhjCgQRWzHrjK fVeReaM1KZnYUodRsgp0FOlJbMZjDO9eGTOwjDlGaYPwpqn5bOCBPOed3Z+xxnnYEw 0uyBUQ2aizYHGAXSZPgJWg3sPaici4itMCxaPm8iQE0b2XbF2/7EWuy8uQ4xmPkwBb US1nLq1hdqlvw== Message-ID: <6cd817c8de439d62741aef3cb2c0914801f0f962.camel@kernel.org> Subject: Re: [for-next][PATCH 05/31] tracing: Have existing event_command.parse() implementations use helpers From: Tom Zanussi To: Steven Rostedt , Daniel Bristot de Oliveira Cc: Ingo Molnar , Andrew Morton , linux-kernel@vger.kernel.org Date: Thu, 13 Jan 2022 15:58:36 -0600 In-Reply-To: <20220113162058.04731caf@gandalf.local.home> References: <20220111173030.999527342@goodmis.org> <20220111173114.155260134@goodmis.org> <388b9922-4231-6e34-1305-f0b439d9d07c@kernel.org> <20220113162058.04731caf@gandalf.local.home> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Steve, On Thu, 2022-01-13 at 16:20 -0500, Steven Rostedt wrote: > On Thu, 13 Jan 2022 18:03:07 +0100 > Daniel Bristot de Oliveira wrote: > > > I did some debug, and found that the histogram is working. The > > problem is that, > > to read the histogram I pause it to have consistent data: > > > > in tools/tracing/rtla/osnoise_hist.c: > > osnoise_read_trace_hist() { > > [...] > > tracefs_hist_pause(tool->trace.inst, data->trace_hist); > > > > content = tracefs_event_file_read(tool->trace.inst, > > "osnoise", > > "sample_threshold", > > "hist", NULL); > > [...] > > } > > > > and, as far as I got, after this patch, pausing the histogram makes > > it to clear > > up. If I comment the "tracefs_hist_pause" line, "rtla osnoise hist" > > start > > working back again. > > > > Thoughts? > > This is all messed up. I'm removing this patch completely. > > Tom, can you fix this. The issue is that it's putting too much policy > into > the helper functions, which is big no no. > > Specifically, we have: > > int event_trigger_register(struct event_command *cmd_ops, > struct trace_event_file *file, > char *glob, > char *cmd, > char *param, > struct event_trigger_data *trigger_data, > int *n_registered) > { > int ret; > > if (n_registered) > *n_registered = 0; > > ret = cmd_ops->reg(glob, trigger_data, file); > /* > * The above returns on success the # of functions enabled, > * but if it didn't find any functions it returns zero. > * Consider no functions a failure too. > */ > if (!ret) { > cmd_ops->unreg(glob, trigger_data, file); > ret = -ENOENT; > } else if (ret > 0) { > if (n_registered) > *n_registered = ret; > /* Just return zero, not the number of enabled > functions */ > ret = 0; > } > > return ret; > } > > > And in the case of pause, this *will* have ret = 0 on return. And > what > happens is that it removes the trigger completely. > > Look at the code in the histogram on the return: > > ret = event_trigger_register(cmd_ops, file, glob, cmd, param, > trigger_data, &n_registered); > if (ret < 0) > goto out_free; > if ((ret == 0) && (n_registered == 0)) { > if (!(attrs->pause || attrs->cont || attrs->clear)) > ret = -ENOENT; > goto out_free; > } > > It checks for 0 and 0 and only errors if it's not pause, cont, or > clear. > Hence, all three are now broken due to this patch. > > I will not be adding this to this merge window. Yes, you're right, event_trigger_register() is trying to do a little too much, and shouldn't be doing the unreg(). Thanks for finding and figuring that out. I'll fix this and send a new version after the merge window. Tom > > -- Steve