linux-kernel - [-mm PATCH] register_memory/unregister

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Date:	Mon, 11 Feb 2008 09:23:18 -0800
From:	Badari Pulavarty <pbadari@...ibm.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	lkml <linux-kernel@...r.kernel.org>
Cc:	Greg KH <greg@...ah.com>, haveblue@...ibm.com,
	linux-mm <linux-mm@...ck.org>
Subject: [-mm PATCH] register_memory/unregister_memory clean ups

Hi Andrew,

While testing hotplug memory remove against -mm, I noticed
that unregister_memory() is not cleaning up /sysfs entries
correctly. It also de-references structures after destroying
them (luckily in the code which never gets used). So, I cleaned
up the code and fixed the extra reference issue.

Could you please include it in -mm ?

Thanks,
Badari

register_memory()/unregister_memory() never gets called with
"root". unregister_memory() is accessing kobject_name of
the object just freed up. Since no one uses the code,
lets take the code out. And also, make register_memory() static.  

Another bug fix - before calling unregister_memory()
remove_memory_block() gets a ref on kobject. unregister_memory()
need to drop that ref before calling sysdev_unregister().

Signed-off-by: Badari Pulavarty <pbadari@...ibm.com>
---
 drivers/base/memory.c |   22 +++++++---------------
 1 file changed, 7 insertions(+), 15 deletions(-)

Index: linux-2.6.24/drivers/base/memory.c
===================================================================
--- linux-2.6.24.orig/drivers/base/memory.c	2008-02-07 16:59:52.000000000 -0800
+++ linux-2.6.24/drivers/base/memory.c	2008-02-08 15:54:45.000000000 -0800
@@ -62,8 +62,8 @@ void unregister_memory_notifier(struct n
 /*
  * register_memory - Setup a sysfs device for a memory block
  */
-int register_memory(struct memory_block *memory, struct mem_section *section,
-		struct node *root)
+static
+int register_memory(struct memory_block *memory, struct mem_section *section)
 {
 	int error;
 
@@ -71,26 +71,18 @@ int register_memory(struct memory_block 
 	memory->sysdev.id = __section_nr(section);
 
 	error = sysdev_register(&memory->sysdev);
-
-	if (root && !error)
-		error = sysfs_create_link(&root->sysdev.kobj,
-					  &memory->sysdev.kobj,
-					  kobject_name(&memory->sysdev.kobj));
-
 	return error;
 }
 
 static void
-unregister_memory(struct memory_block *memory, struct mem_section *section,
-		struct node *root)
+unregister_memory(struct memory_block *memory, struct mem_section *section)
 {
 	BUG_ON(memory->sysdev.cls != &memory_sysdev_class);
 	BUG_ON(memory->sysdev.id != __section_nr(section));
 
+	/* drop the ref. we got in remove_memory_block() */
+	kobject_put(&memory->sysdev.kobj);
 	sysdev_unregister(&memory->sysdev);
-	if (root)
-		sysfs_remove_link(&root->sysdev.kobj,
-				  kobject_name(&memory->sysdev.kobj));
 }
 
 /*
@@ -361,7 +353,7 @@ static int add_memory_block(unsigned lon
 	mutex_init(&mem->state_mutex);
 	mem->phys_device = phys_device;
 
-	ret = register_memory(mem, section, NULL);
+	ret = register_memory(mem, section);
 	if (!ret)
 		ret = mem_create_simple_file(mem, phys_index);
 	if (!ret)
@@ -415,7 +407,7 @@ int remove_memory_block(unsigned long no
 	mem_remove_simple_file(mem, state);
 	mem_remove_simple_file(mem, phys_device);
 	mem_remove_simple_file(mem, removable);
-	unregister_memory(mem, section, NULL);
+	unregister_memory(mem, section);
 
 	return 0;
 }


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