Re: 2nd attempt: help with dma_alloc_coherent() + dma_free_coherent()

From: Linus Torvalds
Date: Tue Jan 08 2013 - 12:24:19 EST


On Tue, Jan 8, 2013 at 9:17 AM, Jeff Chua <jeff.chua.linux@xxxxxxxxx> wrote:
>
> Interesting, but there are 54 lines under the kernel directories that
> use "dma_alloc_coherent(NULL," followed by "dma_free_coherent(NULL,"

As mentioned, it works on some platforms. That doesn't make it right.

> So, shouldn't they be fixed as well? ... unless they are so old that
> nobody cares anymore ...

Some of the ones I saw are in MIPS or blackfin. Others probably *are*
so old that nobody cares, and happen to work because there's iommu's
or other things that simply don't care about the device.

> # find . -exec grep -H "dma_alloc_coherent(NULL" {} \; | wc -l
> 54
>
> #find . -exec grep -H "dma_free_coherent(NULL" {} \; | wc -l
> 72

Let me tell you about "git grep", so that you never need to do that
disgusting "find -exec grep" ever again.

It does threading, it's fast, and it just works.

Linus
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/