Re: [-mm3 patch]Warning fix: check the return value of kobject_add etc.

From: Cong WANG
Date: Sun Apr 01 2007 - 02:21:04 EST


2007/4/1, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>:
On Sat, 31 Mar 2007 10:30:31 +0800 "Cong WANG" <xiyou.wangcong@xxxxxxxxx> wrote:

> Since kobject_add, sysfs_create_link and sysfs_create_file are marked
> as '__must_check', so we must always check their return values, or gcc
> will give us warnings.
>
> Signed-off-by: Cong WANG <xiyou.wangcong@xxxxxxxxx>
>
> ---
> --- fs/partitions/check.c.orig 2007-03-30 21:35:45.000000000 +0800
> +++ fs/partitions/check.c 2007-03-30 21:49:53.000000000 +0800
> @@ -385,10 +385,16 @@ 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)) {
> + kfree(p);
> + 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")) {
> + kfree(p);
> + return;
> + }
> if (flags & ADDPART_FLAG_WHOLEDISK) {
> static struct attribute addpartattr = {
> .name = "whole_disk",
> @@ -396,7 +402,10 @@ void add_partition(struct gendisk *disk,
> .owner = THIS_MODULE,
> };
>
> - sysfs_create_file(&p->kobj, &addpartattr);
> + if (sysfs_create_file(&p->kobj, &addpartattr)) {
> + kfree(p);
> + return;
> + }
> }
> partition_sysfs_add_subdir(p);
> disk->part[part-1] = p;

Well yes, but the point here it to fix kernel bugs, not to just make the
warnings go away.

The bugs here are that the effects of the kobject_add() and the
sysfs_create_link() are not undone on the error path.

Thanks for your point.


Also, please always prepare patches in `patch -p1' form, as per
http://www.zip.com.au/~akpm/linux/patches/stuff/tpp.txt, thanks.



Sorry. I am confused with this. Does that mean I should make patches
_upon_ the root kernel source directory or first make a copy of the
original source code and then diff against the two dirs? But I was
told that "patches should be based _in_ the root kernel source
directory" and when only one file was modified just to diff it with
the original single file. (See Documentation/SubmittingPatches.)

Can you help out? And should I remake this patch? Thanks again!
-
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