linux-kernel - [PATCH v6 3/4] resource: add walk_system_ram_res

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Date:   Wed,  4 Jul 2018 12:10:37 +0800
From:   Baoquan He <bhe@...hat.com>
To:     linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
        robh+dt@...nel.org, dan.j.williams@...el.com,
        nicolas.pitre@...aro.org, josh@...htriplett.org,
        fengguang.wu@...el.com, bp@...e.de, andy.shevchenko@...il.com
Cc:     patrik.r.jakobsson@...il.com, airlied@...ux.ie, kys@...rosoft.com,
        haiyangz@...rosoft.com, sthemmin@...rosoft.com,
        dmitry.torokhov@...il.com, frowand.list@...il.com,
        keith.busch@...el.com, jonathan.derrick@...el.com,
        lorenzo.pieralisi@....com, bhelgaas@...gle.com, tglx@...utronix.de,
        brijesh.singh@....com, jglisse@...hat.com, thomas.lendacky@....com,
        gregkh@...uxfoundation.org, baiyaowei@...s.chinamobile.com,
        richard.weiyang@...il.com, devel@...uxdriverproject.org,
        linux-input@...r.kernel.org, linux-nvdimm@...ts.01.org,
        devicetree@...r.kernel.org, linux-pci@...r.kernel.org,
        ebiederm@...ssion.com, vgoyal@...hat.com, dyoung@...hat.com,
        yinghai@...nel.org, kexec@...ts.infradead.org, monstr@...str.eu,
        davem@...emloft.net, chris@...kel.net, jcmvbkbc@...il.com,
        gustavo@...ovan.org, maarten.lankhorst@...ux.intel.com,
        seanpaul@...omium.org, linux-parisc@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, Baoquan He <bhe@...hat.com>
Subject: [PATCH v6 3/4] resource: add walk_system_ram_res_rev()

This function, being a variant of walk_system_ram_res() introduced in
commit 8c86e70acead ("resource: provide new functions to walk through
resources"), walks through a list of all the resources of System RAM
in reversed order, i.e., from higher to lower.

It will be used in kexec_file code.

Signed-off-by: Baoquan He <bhe@...hat.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Brijesh Singh <brijesh.singh@....com>
Cc: "Jérôme Glisse" <jglisse@...hat.com>
Cc: Borislav Petkov <bp@...e.de>
Cc: Tom Lendacky <thomas.lendacky@....com>
Cc: Wei Yang <richard.weiyang@...il.com>
---
 include/linux/ioport.h |  3 +++
 kernel/resource.c      | 40 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+)

diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index b7456ae889dd..066cc263e2cc 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -279,6 +279,9 @@ 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 6d647a3824b1..4c5fbef4ea24 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -23,6 +23,8 @@
 #include <linux/pfn.h>
 #include <linux/mm.h>
 #include <linux/resource_ext.h>
+#include <linux/string.h>
+#include <linux/vmalloc.h>
 #include <asm/io.h>
 
 
@@ -443,6 +445,44 @@ int walk_system_ram_res(u64 start, u64 end, void *arg,
 }
 
 /*
+ * 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 *))
+{
+	unsigned long flags;
+	struct resource *res;
+	int ret = -1;
+
+	flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
+
+	read_lock(&resource_lock);
+	list_for_each_entry_reverse(res, &iomem_resource.child, sibling) {
+		if (start >= end)
+			break;
+		if ((res->flags & flags) != flags)
+			continue;
+		if (res->desc != IORES_DESC_NONE)
+			continue;
+		if (res->end < start)
+			break;
+
+		if ((res->end >= start) && (res->start < end)) {
+			ret = (*func)(res, arg);
+			if (ret)
+				break;
+		}
+		end = res->start - 1;
+
+	}
+	read_unlock(&resource_lock);
+	return ret;
+}
+
+/*
  * This function calls the @func callback against all memory ranges, which
  * are ranges marked as IORESOURCE_MEM and IORESOUCE_BUSY.
  */
-- 
2.13.6