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=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 0120FC433E0 for ; Fri, 3 Jul 2020 11:40:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C74B72084C for ; Fri, 3 Jul 2020 11:40:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593776402; bh=j9mk/zoE6UAYWQVw6K+UZFeokVdeFIAtsouE3NU5+I8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=N6BQjbmNEsZpj5Zos9wRYMCuJhrZTKu9zVx2FpeRVqBkiosxBGxTdE9Ktc7c75YEa 5NrxxbL02a1RuiotExpqxp7r3NvMKy3ctB249vwYV6YTzQes1L6d3cCKWBgZgDkTLy fxDcQwxJ/xWNIwdO2id+KyuMqSK9wPuFbLGbaMQk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726039AbgGCLkC (ORCPT ); Fri, 3 Jul 2020 07:40:02 -0400 Received: from mail.kernel.org ([198.145.29.99]:54640 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725984AbgGCLkC (ORCPT ); Fri, 3 Jul 2020 07:40:02 -0400 Received: from localhost (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (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 6ECE420772; Fri, 3 Jul 2020 11:40:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593776401; bh=j9mk/zoE6UAYWQVw6K+UZFeokVdeFIAtsouE3NU5+I8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ngZqbyRcGttY2/0Iru9ipEL+a2cl0bzK5HnkxkGDVJwf54PXu89DJ/hAvRLTQBCtA WGYq0ct4mAMiRYQZPdgiRagjOgwglmr2dCfMGQSFTqOfIJSTwBOT4vraEABxOezMDc ESUtFe8drgUulk7elcY/CEzCrCYZyMB+AVakfmlA= Date: Fri, 3 Jul 2020 07:40:00 -0400 From: Sasha Levin To: Pavel Machek Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Masami Hiramatsu , Tom Zanussi , Steven Rostedt , Greg Kroah-Hartman Subject: Re: [PATCH 4.19 119/131] tracing: Fix event trigger to accept redundant spaces Message-ID: <20200703114000.GG2722994@sasha-vm> References: <20200629153502.2494656-1-sashal@kernel.org> <20200629153502.2494656-120-sashal@kernel.org> <20200702211728.GD5787@amd> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20200702211728.GD5787@amd> Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Thu, Jul 02, 2020 at 11:17:28PM +0200, Pavel Machek wrote: >Hi! > >> commit 6784beada631800f2c5afd567e5628c843362cee upstream. >> >> Fix the event trigger to accept redundant spaces in >> the trigger input. >> >> For example, these return -EINVAL >> >> echo " traceon" > events/ftrace/print/trigger >> echo "traceon if common_pid == 0" > events/ftrace/print/trigger >> echo "disable_event:kmem:kmalloc " > events/ftrace/print/trigger >> >> But these are hard to find what is wrong. >> >> To fix this issue, use skip_spaces() to remove spaces >> in front of actual tokens, and set NULL if there is no >> token. > >For the record, I'm not fan of this one. It is ABI change, not a >bugfix. > >Yes, it makes kernel interface "easier to use". It also changes >interface in the middle of stable series, and if people start relying >on new interface and start putting extra spaces, they'll get nasty >surprise when they move code to the older kernel. We promise users that they can upgrade their kernels and we won't be breaking any of their usecases no matter what. However, if they choose to downgrade their kernels then all bets are off. -- Thanks, Sasha