Re: [-mm3 PATCH] (Retry) Check the return value of kobject_add and etc.

[WANG Cong <xiyou.wangcong@gmail.com>]

On Tue, Apr 10, 2007 at 02:31:06PM +0200, Cornelia Huck wrote:
>On Fri, 6 Apr 2007 10:53:43 +0800,
>WANG Cong <xiyou.wangcong@gmail.com> wrote:
> 
>> OK. Then I send it again. Hopefully it can be accepted this time. ;-p
>
>Looks sane. (Note that there is still a pathological case where
>kobject_put() is not enough to trigger release after the failed
>kobject_add(). I'm sending a fix for that.)
>
><Maybe you want to add one or two lines of explanation for your patch
>again?>

Thanks! My explanation of the patch is already in the first mail of this thread. Now I copy it here and resubmit the patch. Hope you don't mind. ;-p This patch can also be applied to -rc6 tree.



Since kobject_add, sysfs_create_link and sysfs_create_file are marked as '__must_check', we must always check their return values.

Signed-off-by: WANG Cong <xiyou.wangcong@gmail.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>

---
--- linux-2.6.21-rc5-mm4/fs/partitions/check.c.orig     2007-04-05 12:48:29.000000000 +0800
+++ linux-2.6.21-rc5-mm4/fs/partitions/check.c  2007-04-05 23:15:41.000000000 +0800
@@ -385,10 +385,18 @@ void add_partition(struct gendisk *disk,
        p->kobj.parent = &disk->kobj;
        p->kobj.ktype = &ktype_part;
        kobject_init(&p->kobj);
-       kobject_add(&p->kobj);
+       if (kobject_add(&p->kobj)) {
+               kobject_put(&p->kobj);
+               return;
+       }
        if (!disk->part_uevent_suppress)
                kobject_uevent(&p->kobj, KOBJ_ADD);
-       sysfs_create_link(&p->kobj, &block_subsys.kset.kobj, "subsystem");
+       if (sysfs_create_link(&p->kobj, &block_subsys.kset.kobj, "subsystem")) {
+               kobject_uevent(&p->kobj, KOBJ_REMOVE);
+               kobject_del(&p->kobj);
+               kobject_put(&p->kobj);
+               return;
+       }
        if (flags & ADDPART_FLAG_WHOLEDISK) {
                static struct attribute addpartattr = {
                        .name = "whole_disk",
@@ -396,7 +404,13 @@ void add_partition(struct gendisk *disk,
                        .owner = THIS_MODULE,
                };

-               sysfs_create_file(&p->kobj, &addpartattr);
+               if (sysfs_create_file(&p->kobj, &addpartattr)) {
+                       sysfs_remove_link(&p->kobj, "subsystem");
+                       kobject_uevent(&p->kobj, KOBJ_REMOVE);
+                       kobject_del(&p->kobj);
+                       kobject_put(&p->kobj);
+                       return;
+               }
        }
        partition_sysfs_add_subdir(p);
        disk->part[part-1] = p;