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=-6.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_NEOMUTT autolearn=unavailable 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 CC19DC10F0E for ; Mon, 15 Apr 2019 09:18:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A6A4F20656 for ; Mon, 15 Apr 2019 09:18:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727021AbfDOJSR (ORCPT ); Mon, 15 Apr 2019 05:18:17 -0400 Received: from mx2.suse.de ([195.135.220.15]:52350 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725939AbfDOJSR (ORCPT ); Mon, 15 Apr 2019 05:18:17 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 69A23B008; Mon, 15 Apr 2019 09:18:14 +0000 (UTC) Date: Mon, 15 Apr 2019 11:18:12 +0200 From: Petr Mladek To: Alastair D'Silva Cc: 'Alastair D'Silva' , 'Jani Nikula' , 'Joonas Lahtinen' , 'Rodrigo Vivi' , 'David Airlie' , 'Daniel Vetter' , 'Karsten Keil' , 'Jassi Brar' , 'Tom Lendacky' , "'David S. Miller'" , 'Jose Abreu' , 'Kalle Valo' , 'Stanislaw Gruszka' , 'Benson Leung' , 'Enric Balletbo i Serra' , "'James E.J. Bottomley'" , "'Martin K. Petersen'" , 'Greg Kroah-Hartman' , 'Alexander Viro' , 'Sergey Senozhatsky' , 'Steven Rostedt' , 'Andrew Morton' , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, ath10k@lists.infradead.org, linux-wireless@vger.kernel.org, linux-scsi@vger.kernel.org, linux-fbdev@vger.kernel.org, devel@driverdev.osuosl.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH 2/4] lib/hexdump.c: Optionally suppress lines of filler bytes Message-ID: <20190415091812.s4e5zlwldbe62ego@pathway.suse.cz> References: <20190410031720.11067-1-alastair@au1.ibm.com> <20190410031720.11067-3-alastair@au1.ibm.com> <20190412140353.mgvksn3yk6n65hbk@pathway.suse.cz> <093101d4f187$612f0f20$238d2d60$@d-silva.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <093101d4f187$612f0f20$238d2d60$@d-silva.org> User-Agent: NeoMutt/20170912 (1.9.0) Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org On Sat 2019-04-13 09:28:03, Alastair D'Silva wrote: > > -----Original Message----- > > From: Petr Mladek > > Sent: Saturday, 13 April 2019 12:04 AM > > To: Alastair D'Silva > > Cc: alastair@d-silva.org; Jani Nikula ; > Joonas > > Lahtinen ; Rodrigo Vivi > > ; David Airlie ; Daniel Vetter > > ; Karsten Keil ; Jassi Brar > > ; Tom Lendacky ; > > David S. Miller ; Jose Abreu > > ; Kalle Valo ; > > Stanislaw Gruszka ; Benson Leung > > ; Enric Balletbo i Serra > > ; James E.J. Bottomley > > ; Martin K. Petersen ; > > Greg Kroah-Hartman ; Alexander Viro > > ; Sergey Senozhatsky > > ; Steven Rostedt ; > > Andrew Morton ; intel- > > gfx@lists.freedesktop.org; dri-devel@lists.freedesktop.org; linux- > > kernel@vger.kernel.org; netdev@vger.kernel.org; > > ath10k@lists.infradead.org; linux-wireless@vger.kernel.org; linux- > > scsi@vger.kernel.org; linux-fbdev@vger.kernel.org; > > devel@driverdev.osuosl.org; linux-fsdevel@vger.kernel.org > > Subject: Re: [PATCH 2/4] lib/hexdump.c: Optionally suppress lines of > filler > > bytes > > > > On Wed 2019-04-10 13:17:18, Alastair D'Silva wrote: > > > From: Alastair D'Silva > > > > > > Some buffers may only be partially filled with useful data, while the > > > rest is padded (typically with 0x00 or 0xff). > > > > > > This patch introduces flags which allow lines of padding bytes to be > > > suppressed, making the output easier to interpret: > > > HEXDUMP_SUPPRESS_0X00, HEXDUMP_SUPPRESS_0XFF > > > > > > The first and last lines are not suppressed by default, so the > > > function always outputs something. This behaviour can be further > > > controlled with the HEXDUMP_SUPPRESS_FIRST & > > HEXDUMP_SUPPRESS_LAST flags. > > > > > > An inline wrapper function is provided for backwards compatibility > > > with existing code, which maintains the original behaviour. > > > > > > > > diff --git a/lib/hexdump.c b/lib/hexdump.c index > > > b8a164814744..2f3bafb55a44 100644 > > > --- a/lib/hexdump.c > > > +++ b/lib/hexdump.c > > > +void print_hex_dump_ext(const char *level, const char *prefix_str, > > > + int prefix_type, int rowsize, int groupsize, > > > + const void *buf, size_t len, u64 flags) > > > { > > > const u8 *ptr = buf; > > > - int i, linelen, remaining = len; > > > + int i, remaining = len; > > > unsigned char linebuf[64 * 3 + 2 + 64 + 1]; > > > + bool first_line = true; > > > > > > if (rowsize != 16 && rowsize != 32 && rowsize != 64) > > > rowsize = 16; > > > > > > for (i = 0; i < len; i += rowsize) { > > > - linelen = min(remaining, rowsize); > > > + bool skip = false; > > > + int linelen = min(remaining, rowsize); > > > + > > > remaining -= rowsize; > > > > > > + if (flags & HEXDUMP_SUPPRESS_0X00) > > > + skip = buf_is_all(ptr + i, linelen, 0x00); > > > + > > > + if (!skip && (flags & HEXDUMP_SUPPRESS_0XFF)) > > > + skip = buf_is_all(ptr + i, linelen, 0xff); > > > + > > > + if (first_line && !(flags & HEXDUMP_SUPPRESS_FIRST)) > > > + skip = false; > > > + > > > + if (remaining <= 0 && !(flags & HEXDUMP_SUPPRESS_LAST)) > > > + skip = false; > > > + > > > + if (skip) > > > + continue; > > > > IMHO, quietly skipping lines could cause a lot of confusion, espcially > when the address is not printed. > > > It's up to the caller to decide how they want it displayed. I wonder who would want to quietly skip some data values. Are you using it yourself? Could you please provide an example? I do not see why we would need to complicate the API and code by this. The behavior proposed by Tvrtko Ursulin makes much more sense. I mean https://lkml.kernel.org/r/929244ed-cc7f-b0f3-b5ac-50e798e83188@linux.intel.com > > I wonder how it would look like when we print something like: > > > > --- skipped XX lines full of 0x00 --- > > This could be added as a later enhancement, with a new flag (eg. > HEXDUMP_SUPPRESS_VERBOSE). Who will add this later? Frankly, this looks like a half baked feature that it good enough for you. If you want it upstream, it must behave reasonably and it must be worth it. Best Regards, Petr