From patchwork Thu Apr 26 01:18:37 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wei Yang X-Patchwork-Id: 10364525 X-Patchwork-Delegate: bhelgaas@google.com Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 7EE26602DC for ; Thu, 26 Apr 2018 01:18:49 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 6D20628FB8 for ; Thu, 26 Apr 2018 01:18:49 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6181829039; Thu, 26 Apr 2018 01:18:49 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, FREEMAIL_FROM, MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D924528FB8 for ; Thu, 26 Apr 2018 01:18:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751276AbeDZBSr (ORCPT ); Wed, 25 Apr 2018 21:18:47 -0400 Received: from mail-pg0-f66.google.com ([74.125.83.66]:45725 "EHLO mail-pg0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751231AbeDZBSp (ORCPT ); Wed, 25 Apr 2018 21:18:45 -0400 Received: by mail-pg0-f66.google.com with SMTP id i29so13092289pgn.12; Wed, 25 Apr 2018 18:18:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:reply-to:references:mime-version :content-disposition:in-reply-to:user-agent; bh=4kNkWmBMLwYwkanuOw029/8icdFl0ylrPDyfIBljynY=; b=gF3JTg0gE6kJhD/Rs0tiy8lHBSRwSAga8s9pKH6nM2pcXy9cfytQWnOCBO0D4kvutO tRh8SZQ6Byb9EVCOATG4+l/lcVk8ssMvAMOVgsDApZv9F1tqysgx59aWmLMkShyw7JDx ad8EBgqOFHh6kq5/f/ciAr1try5fgiJzT9EGQq5083AZdcuwjeVKkMBCut8idPznZWFD DdZbYVDCrQZn+OXI559v5EIM+cShrnetD0HhZZako2oS5OVX9EDe8f05X5+Vhx4tklGO F+8TE2nK7s2fCBNch3uGR1x20p5BGyeTZpj0kVp8xJ/Sanb5zXuubLQOw0dDQqoK+fWM No3w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:reply-to :references:mime-version:content-disposition:in-reply-to:user-agent; bh=4kNkWmBMLwYwkanuOw029/8icdFl0ylrPDyfIBljynY=; b=rQTDxjjv2u8YRcjl72lfCM6m0WjaHhpRJ5Ioos6v8bXEqXFxctV2hO7zD2K7bax+k7 clDuSOLveKMqmTSeLztrt41IUpTAtPVO4Fw3umCTdF6Pck3b+tADVBU+13u4hJOAZwGT w6oNuswhsM92L00Q0UlN4A46Y1LRFvhVq3qQ2sdAKycKlM5zKb68YtCfstroWeXwnEmS YAtUf7r/v/MruCDt/krv3wBoSZYKmfYyCokRQIOgvdC2nYzgqilz0W6N8MmjVnmttYCA jmt2Y567SCV7Bty6inAqsNdgIJ41O3Wz77pL8cALme1DFolAeDbXPiF5dRdbNeLxfk5q yeAA== X-Gm-Message-State: ALQs6tBY66kAq/0CWb8yBhNseo9jkgaxbX+dD/6trJ8omsB1Idzpkr5p Gk1U/KQi5usnmbifhDgjysA= X-Google-Smtp-Source: AIpwx4/FSF6CxG1+Rapa0SjggkEXF1+y+btOIGa7A+X6q1HRRajEI34+ZTPWUd+smJkN00mS7dtq1w== X-Received: by 10.101.92.134 with SMTP id a6mr9901331pgt.273.1524705524623; Wed, 25 Apr 2018 18:18:44 -0700 (PDT) Received: from localhost ([185.92.221.13]) by smtp.gmail.com with ESMTPSA id s2sm34612118pfb.66.2018.04.25.18.18.42 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 25 Apr 2018 18:18:43 -0700 (PDT) Date: Thu, 26 Apr 2018 09:18:37 +0800 From: Wei Yang To: Baoquan He Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, robh+dt@kernel.org, dan.j.williams@intel.com, nicolas.pitre@linaro.org, josh@joshtriplett.org, Patrik Jakobsson , David Airlie , "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , Dmitry Torokhov , Frank Rowand , Keith Busch , Jonathan Derrick , Lorenzo Pieralisi , Bjorn Helgaas , Thomas Gleixner , Brijesh Singh , =?iso-8859-1?B?Suly9G1l?= Glisse , Borislav Petkov , Tom Lendacky , Greg Kroah-Hartman , Yaowei Bai , Wei Yang , devel@linuxdriverproject.org, linux-input@vger.kernel.org, linux-nvdimm@lists.01.org, devicetree@vger.kernel.org, linux-pci@vger.kernel.org Subject: Re: [PATCH v3 1/3] resource: Use list_head to link sibling resource Message-ID: <20180426011837.GA79340@WeideMacBook-Pro.local> Reply-To: Wei Yang References: <20180419001848.3041-1-bhe@redhat.com> <20180419001848.3041-2-bhe@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20180419001848.3041-2-bhe@redhat.com> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP On Thu, Apr 19, 2018 at 08:18:46AM +0800, Baoquan He wrote: >The struct resource uses singly linked list to link siblings. It's not >easy to do reverse iteration on sibling list. So replace it with list_head. > Hi, Baoquan Besides changing the data structure, I have another proposal to do the reverse iteration. Which means it would not affect other users, if you just want a reverse iteration. BTW, I don't think Andrew suggest to use linked-list directly. What he wants is a better solution to your first proposal in https://patchwork.kernel.org/patch/10300819/. Below is my proposal of resource reverse iteration without changing current design. From 5d7145d44fe48b98572a03884fa3a3aa82e3cef9 Mon Sep 17 00:00:00 2001 From: Wei Yang Date: Sat, 24 Mar 2018 23:25:46 +0800 Subject: [PATCH] kernel/resource: add walk_system_ram_res_rev() As discussed on https://patchwork.kernel.org/patch/10300819/, this patch comes up with a variant implementation of walk_system_ram_res_rev(), which uses iteration instead of allocating array to store those resources. Signed-off-by: Wei Yang --- include/linux/ioport.h | 3 ++ kernel/resource.c | 113 +++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 116 insertions(+) diff --git a/include/linux/ioport.h b/include/linux/ioport.h index da0ebaec25f0..473f1d9cb97e 100644 --- a/include/linux/ioport.h +++ b/include/linux/ioport.h @@ -277,6 +277,9 @@ extern int walk_system_ram_res(u64 start, u64 end, void *arg, int (*func)(struct resource *, void *)); extern int +walk_system_ram_res_rev(u64 start, u64 end, void *arg, + int (*func)(struct resource *, void *)); +extern int walk_iomem_res_desc(unsigned long desc, unsigned long flags, u64 start, u64 end, void *arg, int (*func)(struct resource *, void *)); diff --git a/kernel/resource.c b/kernel/resource.c index 769109f20fb7..d4ec5fbc6875 100644 --- a/kernel/resource.c +++ b/kernel/resource.c @@ -73,6 +73,38 @@ static struct resource *next_resource(struct resource *p, bool sibling_only) return p->sibling; } +static struct resource *prev_resource(struct resource *p, bool sibling_only) +{ + struct resource *prev; + if (NULL == iomem_resource.child) + return NULL; + + if (p == NULL) { + prev = iomem_resource.child; + while (prev->sibling) + prev = prev->sibling; + } else { + if (p->parent->child == p) { + return p->parent; + } + + for (prev = p->parent->child; prev->sibling != p; + prev = prev->sibling) {} + } + + /* Caller wants to traverse through siblings only */ + if (sibling_only) + return prev; + + for (;prev->child;) { + prev = prev->child; + + while (prev->sibling) + prev = prev->sibling; + } + return prev; +} + static void *r_next(struct seq_file *m, void *v, loff_t *pos) { struct resource *p = v; @@ -401,6 +433,47 @@ static int find_next_iomem_res(struct resource *res, unsigned long desc, return 0; } +/* + * Finds the highest iomem resource existing within [res->start.res->end). + * The caller must specify res->start, res->end, res->flags, and optionally + * desc. If found, returns 0, res is overwritten, if not found, returns -1. + * This function walks the whole tree and not just first level children until + * and unless first_level_children_only is true. + */ +static int find_prev_iomem_res(struct resource *res, unsigned long desc, + bool first_level_children_only) +{ + struct resource *p; + + BUG_ON(!res); + BUG_ON(res->start >= res->end); + + read_lock(&resource_lock); + + for (p = prev_resource(NULL, first_level_children_only); p; + p = prev_resource(p, first_level_children_only)) { + if ((p->flags & res->flags) != res->flags) + continue; + if ((desc != IORES_DESC_NONE) && (desc != p->desc)) + continue; + if (p->end < res->start || p->child == iomem_resource.child) { + p = NULL; + break; + } + if ((p->end >= res->start) && (p->start < res->end)) + break; + } + + read_unlock(&resource_lock); + if (!p) + return -1; + /* copy data */ + resource_clip(res, p->start, p->end); + res->flags = p->flags; + res->desc = p->desc; + return 0; +} + static int __walk_iomem_res_desc(struct resource *res, unsigned long desc, bool first_level_children_only, void *arg, @@ -422,6 +495,27 @@ static int __walk_iomem_res_desc(struct resource *res, unsigned long desc, return ret; } +static int __walk_iomem_res_rev_desc(struct resource *res, unsigned long desc, + bool first_level_children_only, + void *arg, + int (*func)(struct resource *, void *)) +{ + u64 orig_start = res->start; + int ret = -1; + + while ((res->start < res->end) && + !find_prev_iomem_res(res, desc, first_level_children_only)) { + ret = (*func)(res, arg); + if (ret) + break; + + res->end = res->start?(res->start - 1):0; + res->start = orig_start; + } + + return ret; +} + /* * Walks through iomem resources and calls func() with matching resource * ranges. This walks through whole tree and not just first level children. @@ -468,6 +562,25 @@ int walk_system_ram_res(u64 start, u64 end, void *arg, arg, func); } +/* + * This function, being a variant of walk_system_ram_res(), calls the @func + * callback against all memory ranges of type System RAM which are marked as + * IORESOURCE_SYSTEM_RAM and IORESOUCE_BUSY in reversed order, i.e., from + * higher to lower. + */ +int walk_system_ram_res_rev(u64 start, u64 end, void *arg, + int (*func)(struct resource *, void *)) +{ + struct resource res; + + res.start = start; + res.end = end; + res.flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY; + + return __walk_iomem_res_rev_desc(&res, IORES_DESC_NONE, true, + arg, func); +} + /* * This function calls the @func callback against all memory ranges, which * are ranges marked as IORESOURCE_MEM and IORESOUCE_BUSY.