Re: alloc/free quesion in ixp4xx driver

MikeW
2007-05-17T17:08:49Z

Phil Endecott <spam_from_linux_mtd <at> chezphil.org> writes:

>
> Dear MTD experts,
>
> I have been looking at the MTD ixp4xx driver
> (drivers/mtd/maps/ixp4xx.c), mainly as an example of something that
> uses the ixp4xx expansion bus, and I have a couple of questions. I
> apologise for being a "newbie" on this subject, I have not written a
> lot of kernel code.
>
> - In ixp4xx_flash_probe(), a struct ixp4xx_flash_info in kalloc()ed.
> Where is it freed?
>
> - In ixp4xx_flash_remove() you have:
> release_resource(info->res);
> kfree(info->res);
> In other places where release_resource() is called I do not see a
> call to kfree(). Is this right?
>
> Most likely, this is all OK and I need to learn more about how these
> functions should be used. But my thought on seeing this was that the
> kfree() should have been freeing info, not info->res.
>
> I am also uncertain about release_resource() vs. release_mem_region().
> Are they interchangeable?
>
> I have been looking at 2.6.21, but a quick check at
>
>
http://git.infradead.org/?p=mtd-2.6.git;a=blob;
f=drivers/mtd/maps/ixp4xx.c;h=7a828e3e6446d7f9254f083d3b02bb2e9e02e9e0;
hb=HEAD

> suggests that it is the same in your tree (if I have
understood gitweb properly).
>
> Many thanks,
>
> Phil.

Don't think it should kfree(info->res), the release_resource() sorts
out the allocated mem region.

But there should be a kfree(info) somewhere in the driver.

My guess is that you have spotted a typo, and there should be a
kfree(info) next, just outside the if (info->res) block.

The existing code would lead to a memory leak IMHO.
Want to try out the patch !!??

Regards,
MikeW