linux-kernel - Re: [RFC PATCH] arm: dma-mapping: fallback allocation for cma failure

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Message-ID: <xa1tmweajy4b.fsf@mina86.com>
Date:	Wed, 21 May 2014 17:22:44 -1000
From:	Michal Nazarewicz <mina86@...a86.com>
To:	Gioh Kim <gioh.kim@....com>, Joonsoo Kim <iamjoonsoo.kim@....com>
Cc:	Marek Szyprowski <m.szyprowski@...sung.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Heesub Shin <heesub.shin@...sung.com>,
	Mel Gorman <mgorman@...e.de>,
	Johannes Weiner <hannes@...xchg.org>,
	이건호 <gunho.lee@....com>,
	'Chanho Min' <chanho.min@....com>
Subject: Re: [RFC PATCH] arm: dma-mapping: fallback allocation for cma failure

On Thu, May 22 2014, Gioh Kim <gioh.kim@....com> wrote:
> I appreciate your comments.
> The previous patch was ugly. But now it's beautiful! Just 3 lines!
>
> I'm not familiar with kernel patch process.
> Can I have your name at Signed-off-by: line?
> What tag do I have to write your name in?

My Signed-off-by line does not apply in this case.
Documentation/SubmittingPatches describes what Signed-off-by means.

I've added Acked-by below.  You may want to resend this patch using
“git-send-email”.

> --------------------------------- 8< ----------------------------------------------
>  From 135c986cfaa5a7291519308b3d47e58bf9f5af25 Mon Sep 17 00:00:00 2001
> From: Gioh Kim <gioh.kim@....com>
> Date: Tue, 20 May 2014 14:16:20 +0900
> Subject: [PATCH] arm: dma-mapping: add checking cma area initialized
>
> If CMA is turned on and CMA size is set to zero, kernel should
> behave as if CMA was not enabled at compile time.
> Every dma allocation should check existence of cma area
> before requesting memory.
>
> Signed-off-by: Gioh Kim <gioh.kim@....com>
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@....com>

Acked-by: Michal Nazarewicz <mina86@...a86.com>

But like before, if someone with more ARM knowledge could take a look at
it, it would be awesome.

> ---
>   arch/arm/mm/dma-mapping.c |    7 ++++---
>   1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
> index 18e98df..9173a13 100644
> --- a/arch/arm/mm/dma-mapping.c
> +++ b/arch/arm/mm/dma-mapping.c
> @@ -390,12 +390,13 @@ static int __init atomic_pool_init(void)
>          if (!pages)
>                  goto no_pages;
>
> -       if (IS_ENABLED(CONFIG_DMA_CMA))
> +       if (dev_get_cma_area(NULL))
>                  ptr = __alloc_from_contiguous(NULL, pool->size, prot, &page,
>                                                atomic_pool_init);
>          else
>                  ptr = __alloc_remap_buffer(NULL, pool->size, gfp, prot, &page,
>                                             atomic_pool_init);
> +
>          if (ptr) {
>                  int i;
>
> @@ -701,7 +702,7 @@ static void *__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
>                  addr = __alloc_simple_buffer(dev, size, gfp, &page);
>          else if (!(gfp & __GFP_WAIT))
>                  addr = __alloc_from_pool(size, &page);
> -       else if (!IS_ENABLED(CONFIG_DMA_CMA))
> +       else if (!dev_get_cma_area(dev))
>                  addr = __alloc_remap_buffer(dev, size, gfp, prot, &page, caller);
>          else
>                  addr = __alloc_from_contiguous(dev, size, prot, &page, caller);
> @@ -790,7 +791,7 @@ static void __arm_dma_free(struct device *dev, size_t size, void *cpu_addr,
>                  __dma_free_buffer(page, size);
>          } else if (__free_from_pool(cpu_addr, size)) {
>                  return;
> -       } else if (!IS_ENABLED(CONFIG_DMA_CMA)) {
> +       } else if (!dev_get_cma_area(dev)) {
>                  __dma_free_remap(cpu_addr, size);
>                  __dma_free_buffer(page, size);
>          } else {
> --
> 1.7.9.5

-- 
Best regards,                                         _     _
.o. | Liege of Serenely Enlightened Majesty of      o' \,=./ `o
..o | Computer Science,  Michał “mina86” Nazarewicz    (o o)
ooo +--<mpn@...gle.com>--<xmpp:mina86@...ber.org>--ooO--(_)--Ooo--
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