[U-Boot] [PATCH v2 10/14] linux_compat: introduce GFP_DMA flag for kmalloc()

Lukasz Majewski
2015-07-13T07:52:46Z

Hi Masahiro,

> It does not seem efficient to always return cache-aligned memory.
> Return aligned memory only when GFP_DMA flag is given.
>
> My main motivation for this commit is to refactor device_probe()
> and device_free() in the next commit. DM_FLAG_ALLOC_PRIV_DMA
> should be handled more easily.
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> ---
>
> Changes in v2: None
>
> include/linux/compat.h | 1 +
> lib/linux_compat.c | 5 ++++-
> 2 files changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/compat.h b/include/linux/compat.h
> index fbebf91..13386c9 100644
> --- a/include/linux/compat.h
> +++ b/include/linux/compat.h
> @@ -41,6 +41,7 @@ extern struct p_current *current;
> #define GFP_NOFS ((gfp_t) 0)
> #define GFP_USER ((gfp_t) 0)
> #define __GFP_NOWARN ((gfp_t) 0)
> +#define GFP_DMA ((__force gfp_t)0x01u)
> #define __GFP_ZERO ((__force gfp_t)0x8000u) /* Return
> zeroed page on success */
> void *kmalloc(size_t size, int flags);
> diff --git a/lib/linux_compat.c b/lib/linux_compat.c
> index a936a7e..6da0cfa 100644
> --- a/lib/linux_compat.c
> +++ b/lib/linux_compat.c
> @@ -18,7 +18,10 @@ void *kmalloc(size_t size, int flags)
> {
> void *p;
>
> - p = memalign(ARCH_DMA_MINALIGN, size);
> + if (flags & GFP_DMA)
> + p = memalign(ARCH_DMA_MINALIGN, size);
> + else
> + p = malloc(size);
> if (flags & __GFP_ZERO)
> memset(p, 0, size);
>

Reviewed-by: Lukasz Majewski <l.majewski@samsung.com>

I hope that all places where kmalloc without GFP_DMA set is called
and implicitly require memalign'ed memory would be changed accordingly.

Otherwise we would have nasty, hard to find bugs.

--
Best regards,

Lukasz Majewski

Samsung R&D Institute Poland (SRPOL) | Linux Platform Group