Patchwork [2/9] v3 Add mutex for adding/removing memory blocks

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Submitter Nathan Fontenot
Date Oct. 1, 2010, 6:29 p.m.
Message ID <4CA62896.2060307@austin.ibm.com>
Download mbox | patch
Permalink /patch/66483/
State Not Applicable
Headers show

Comments

Nathan Fontenot - Oct. 1, 2010, 6:29 p.m.
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>

---
 drivers/base/memory.c |    7 +++++++
 1 file changed, 7 insertions(+)
holt@sgi.com - Oct. 1, 2010, 6:45 p.m.
On Fri, Oct 01, 2010 at 01:29:42PM -0500, Nathan Fontenot wrote:
> 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>

I am fine with this patch by itself, but its only real function is
to protect the count introduced by the next patch.  You might want to
combine the patches, but if not, that is fine as well.

Robin
KAMEZAWA Hiroyuki - Oct. 5, 2010, 5:06 a.m.
On Fri, 01 Oct 2010 13:29:42 -0500
Nathan Fontenot <nfont@austin.ibm.com> wrote:

> 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: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

Patch

Index: linux-next/drivers/base/memory.c
===================================================================
--- linux-next.orig/drivers/base/memory.c	2010-09-30 14:09:36.000000000 -0500
+++ linux-next/drivers/base/memory.c	2010-09-30 14:12:41.000000000 -0500
@@ -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 = {
@@ -476,6 +478,8 @@ 
 	if (!mem)
 		return -ENOMEM;
 
+	mutex_lock(&mem_sysfs_mutex);
+
 	mem->phys_index = __section_nr(section);
 	mem->state = state;
 	mutex_init(&mem->state_mutex);
@@ -496,6 +500,7 @@ 
 			ret = register_mem_sect_under_node(mem, nid);
 	}
 
+	mutex_unlock(&mem_sysfs_mutex);
 	return ret;
 }
 
@@ -504,6 +509,7 @@ 
 {
 	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);
@@ -512,6 +518,7 @@ 
 	mem_remove_simple_file(mem, removable);
 	unregister_memory(mem, section);
 
+	mutex_unlock(&mem_sysfs_mutex);
 	return 0;
 }