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 X-Spam-Level: X-Spam-Status: No, score=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B3694C47082 for ; Tue, 8 Jun 2021 12:59:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 916BA61351 for ; Tue, 8 Jun 2021 12:59:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232705AbhFHNBY (ORCPT ); Tue, 8 Jun 2021 09:01:24 -0400 Received: from smtp2.axis.com ([195.60.68.18]:6907 "EHLO smtp2.axis.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230009AbhFHNBX (ORCPT ); Tue, 8 Jun 2021 09:01:23 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=axis.com; q=dns/txt; s=axis-central1; t=1623157170; x=1654693170; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=b0NmHxsg1aBuIl6v7KAzslccYdqY1RPSbbU0UE9Pw/E=; b=E1JC4VOkMnZo3vg3q26UIOosaCdaefk5mbeTz9P6UksdmfjZFItMJ74h snX70Obn4XTVgY1Do0NPO0FUhyE96hNh56PWyhawGsMdb3wXR+m96+gwb a+qxKS5/YJeuhxOSrwUPQs2EuUBXDMDdrwj+lJduLO3jlUYUBUTDulzkx DQqWSp+rSG4pE+/oEJGfBq+EY/sKBOD2uEplizAsJVtsVuoT0dLjCzhLu NmqRiyc8qilzJ+iijf/QCcLm/egU26VFOD0vNwfBtqCMFc2Wd7bT8IoAC W9pUVhGwslRccuujG2YBDqIAMTxtDeJ9oAYOuVVlfP0mXEjOOBZ39AQST A==; Date: Tue, 8 Jun 2021 14:59:27 +0200 From: Vincent Whitchurch To: Steven Rostedt CC: Christoph Hellwig , Ingo Molnar , kernel , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] tracing: Export tracing_start() and tracing_stop() Message-ID: <20210608125927.GA4095@axis.com> References: <20210602080118.21627-1-vincent.whitchurch@axis.com> <20210607091432.667ff0ba@oasis.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20210607091432.667ff0ba@oasis.local.home> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 07, 2021 at 03:14:32PM +0200, Steven Rostedt wrote: > That said though, tracing_stop() is probably not what is wanted > (unless its for a suspend to ram thing). According to the above > description, the author really wants to use "tracing_off()" and not > "tracing_stop()" as tracing_off() is faster and can be turned back on > in user-space with the "tracing_on" file in tracefs, where as, > tracing_stop() can not be. tracing_stop() needs a tracing_start() to > get it going again. > > And tracing_off() is already EXPORT_SYMBOL_GPL() (as it is commonly > used for debugging of modules). Again, it shouldn't have any in-kernel > users in modules, because, like I stated above, it's similar to > trace_printk() which should be removed before pushing to Linus. > > I'll NAK this patch for a different reason. Use tracing_off() instead. Right, thanks, that's certainly much simpler. I'd only used tracing_stop() before and never noticed that tracing_on can't be used to restart tracing, probably because the kind of problems I used it for usually resulted in the system needing a restart anyway to be usable.