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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,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 8AC5FC43218 for ; Sun, 28 Apr 2019 16:57:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 633B820693 for ; Sun, 28 Apr 2019 16:57:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727032AbfD1Q5y (ORCPT ); Sun, 28 Apr 2019 12:57:54 -0400 Received: from mga14.intel.com ([192.55.52.115]:30306 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726847AbfD1Q5x (ORCPT ); Sun, 28 Apr 2019 12:57:53 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 28 Apr 2019 09:57:53 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,406,1549958400"; d="scan'208";a="319749754" Received: from smile.fi.intel.com (HELO smile) ([10.237.72.86]) by orsmga005.jf.intel.com with ESMTP; 28 Apr 2019 09:57:48 -0700 Received: from andy by smile with local (Exim 4.92) (envelope-from ) id 1hKn7Z-0006IZ-N6; Sun, 28 Apr 2019 19:57:45 +0300 Date: Sun, 28 Apr 2019 19:57:45 +0300 From: Andy Shevchenko To: Yury Norov Cc: Andrew Morton , Rasmus Villemoes , Dmitry Torokhov , "David S . Miller" , Stephen Rothwell , Amritha Nambiar , Willem de Bruijn , Kees Cook , Matthew Wilcox , "Tobin C . Harding" , Will Deacon , Miklos Szeredi , Vineet Gupta , Chris Wilson , Arnaldo Carvalho de Melo , Yury Norov , linux-kernel@vger.kernel.org, Jens Axboe , Steffen Klassert Subject: Re: [PATCH 4/6] lib: rework bitmap_parse() Message-ID: <20190428165745.GX9224@smile.fi.intel.com> References: <20190428032936.1317-1-ynorov@marvell.com> <20190428032936.1317-5-ynorov@marvell.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190428032936.1317-5-ynorov@marvell.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo 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 Sat, Apr 27, 2019 at 08:29:34PM -0700, Yury Norov wrote: > bitmap_parse() is ineffective and full of opaque variables and opencoded > parts. It leads to hard understanding of it. This rework includes: > - remove bitmap_shift_left() call from the cycle. Now it makes the > complexity of the algorithm as O(nbits^2). In the suggested approach > the input string is parsed in reverse direction, so no shifts needed; > - relax requirement on a single comma and no white spaces between chunks. > It is considered useful in scripting, and it aligns with > bitmap_parselist(); > - split bitmap_parse() to small readable helpers; > - make an explicit calculation of the end of input line at the > beginning, so users of the bitmap_parse() won't bother doing this. > +static inline bool in_str(const char *start, const char *ptr) > +{ > + return start <= ptr; > +} > + I don't see how it's better than explicit use. Moreover, explicit use shows the exact condition in-line. Even by used characters it's longer. > +static const char *bitmap_get_hex32_rev(const char *start, > + const char *end, u32 *num) In kernel few functions to work with hex u32 named foo_x32(). I would rather use that. Besides, we spell "reverse" in full. > +{ > + u32 ret = 0; > + int c, i; > + > + if (hex_to_bin(*end) < 0) > + return ERR_PTR(-EINVAL); > + > + for (i = 0; i < 32; i += 4) { > + c = hex_to_bin(*end--); > + if (c < 0) Perhaps we may need similar patch for hex_to_bin() as in the commit 9888a588ea96 ("lib/hexdump.c: return -EINVAL in case of error in hex2bin()") > + return ERR_PTR(-EINVAL); > + > + ret |= c << i; > + > + if (!in_str(start, end) || __end_of_region(*end)) > + goto out; > + } > + > + if (hex_to_bin(*end) >= 0) > + return ERR_PTR(-EOVERFLOW); > +out: > + *num = ret; > + return end; > +} -- With Best Regards, Andy Shevchenko