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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT autolearn=ham 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 30986C43387 for ; Tue, 18 Dec 2018 10:46:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F1C9C217D8 for ; Tue, 18 Dec 2018 10:46:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="acARrZ8S" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726619AbeLRKqd (ORCPT ); Tue, 18 Dec 2018 05:46:33 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:49520 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726364AbeLRKqc (ORCPT ); Tue, 18 Dec 2018 05:46:32 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=eVdR9lHYgwIxzuSNH4ypjLBCr5/5VTkW/iKHFipJKEw=; b=acARrZ8SMv7OG02VMWkIkr5Dd /0APdno5I3UgmIndDgCVAu6y/HDffHq8/7LAe+BENcI5bUOt5NFlpAqo4Rxj+IRJ1LYjHxo2dHdx4 +XOc94/R7CtzYrhn9vscgao/MUV5O15SSwsLbTA0D9TNm6xoAnshjwKojdfeF6yZfjDC0eUMMjTrp LCPr122DPJzkWwYPYtBh/OSgHxErOHaKJrkblvkOxCCHlGucpMi75hNn2QOm7xEMx9gnlKI+4be8B 0JRtOkmwpTvU1e5BR4IAJ3QT/7orXG6ETq/G5VuPpztkvixdW+D0DeXAtXb/FldnQxfAQpaN+/DUz fZJ+jqrzg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1gZCtL-0002gf-VC; Tue, 18 Dec 2018 10:46:24 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 378B320276AC4; Tue, 18 Dec 2018 11:46:22 +0100 (CET) Date: Tue, 18 Dec 2018 11:46:22 +0100 From: Peter Zijlstra To: Suren Baghdasaryan Cc: Greg Kroah-Hartman , Tejun Heo , lizefan@huawei.com, Johannes Weiner , axboe@kernel.dk, dennis@kernel.org, Dennis Zhou , Ingo Molnar , Andrew Morton , Jonathan Corbet , cgroups@vger.kernel.org, linux-mm , linux-doc@vger.kernel.org, LKML , kernel-team@android.com Subject: Re: [PATCH 6/6] psi: introduce psi monitor Message-ID: <20181218104622.GB15430@hirez.programming.kicks-ass.net> References: <20181214171508.7791-1-surenb@google.com> <20181214171508.7791-7-surenb@google.com> <20181217162223.GD2218@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 17, 2018 at 05:21:05PM -0800, Suren Baghdasaryan wrote: > On Mon, Dec 17, 2018 at 8:22 AM Peter Zijlstra wrote: > > How well has this thing been fuzzed? Custom string parser, yay! > > Honestly, not much. Normal cases and some obvious corner cases. Will > check if I can use some fuzzer to get more coverage or will write a > script. > I'm not thrilled about writing a custom parser, so if there is a > better way to handle this please advise. The grammar seems fairly simple, something like: some-full = "some" | "full" ; threshold-abs = integer ; threshold-pct = integer, { "%" } ; threshold = threshold-abs | threshold-pct ; window = integer ; trigger = some-full, space, threshold, space, window ; And that could even be expressed as two scanf formats: "%4s %u%% %u" , "%4s %u %u" which then gets your something like: char type[5]; if (sscanf(input, "%4s %u%% %u", &type, &pct, &window) == 3) { // do pct thing } else if (sscanf(intput, "%4s %u %u", &type, &thres, &window) == 3) { // do abs thing } else return -EFAIL; if (!strcmp(type, "some")) { // some } else if (!strcmp(type, "full")) { // full } else return -EFAIL; // do more which seems like a lot less error prone. Alternatively you can use 4 formats: "some %u%% %u" "some %u %u" "full %u%% %u" "full %u %u" and avoid the whole 'type' thing.