From 2938ffbd466d2811a6012609684a2298eef35065 Mon Sep 17 00:00:00 2001
From: Nathan Fontenot <nfont@austin.ibm.com>
Date: Tue, 19 Oct 2010 12:45:24 -0500
Subject: Driver core: Add mutex for adding/removing memory blocks

Add a new mutex for use in adding and removing of memory blocks.  This
is needed to avoid any race conditions in which the same memory block could
be added and removed at the same time.

Signed-off-by: Nathan Fontenot <nfont@austin.ibm.com>
Reviewed-by: Robin Holt <holt@sgi.com>
Reviewed-By: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 63c2560..5185bcf 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -27,6 +27,8 @@
 #include <asm/atomic.h>
 #include <asm/uaccess.h>
 
+static DEFINE_MUTEX(mem_sysfs_mutex);
+
 #define MEMORY_CLASS_NAME	"memory"
 
 static struct sysdev_class memory_sysdev_class = {
@@ -484,6 +486,8 @@ static int add_memory_block(int nid, struct mem_section *section,
 	if (!mem)
 		return -ENOMEM;
 
+	mutex_lock(&mem_sysfs_mutex);
+
 	mem->phys_index = __section_nr(section);
 	mem->state = state;
 	mutex_init(&mem->state_mutex);
@@ -504,6 +508,7 @@ static int add_memory_block(int nid, struct mem_section *section,
 			ret = register_mem_sect_under_node(mem, nid);
 	}
 
+	mutex_unlock(&mem_sysfs_mutex);
 	return ret;
 }
 
@@ -512,6 +517,7 @@ int remove_memory_block(unsigned long node_id, struct mem_section *section,
 {
 	struct memory_block *mem;
 
+	mutex_lock(&mem_sysfs_mutex);
 	mem = find_memory_block(section);
 	unregister_mem_sect_under_nodes(mem);
 	mem_remove_simple_file(mem, phys_index);
@@ -520,6 +526,7 @@ int remove_memory_block(unsigned long node_id, struct mem_section *section,
 	mem_remove_simple_file(mem, removable);
 	unregister_memory(mem, section);
 
+	mutex_unlock(&mem_sysfs_mutex);
 	return 0;
 }
 
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