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Re: [PATCH 1/1] dma-mapping: to avoid exception when cpu_addr is NULL

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On 2016/3/7 19:41, One Thousand Gnomes wrote:
> On Mon, 7 Mar 2016 17:21:25 +0800
> Zhen Lei <thunder.leizhen@huawei.com> wrote:
> 
>> Do this to keep consistent with kfree, which tolerate ptr is NULL.
>>
>> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
> 
> This is inlined code so you are adding extra logic to every single
> instance of a call to the function. What is it's total effect on kernel
> size ?

This a simple if statement, I think it will only generates two instructions.
Maybe I need move it into function dma_free_attrs, as below:
if (!ops->free || !cpu_addr)
	return;

So that, it only generates one instruction. And dma_free_noncoherent can also be impacted.

Or I changed it to BUG_ON(!cpu_addr)?

Otherwise, I move it into ops->free, but that maybe more ARCHs.

> 
> Alan
> 
> .
> 

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[PATCH 1/1] dma-mapping: to avoid exception when cpu_addr is NULL Zhen Lei <thunder.leizhen@huawei.com> - 2016-03-07 10:30 +0100
  Re: [PATCH 1/1] dma-mapping: to avoid exception when cpu_addr is NULL "Leizhen (ThunderTown)" <thunder.leizhen@huawei.com> - 2016-03-07 11:50 +0100
    Re: [PATCH 1/1] dma-mapping: to avoid exception when cpu_addr is  NULL Andrew Morton <akpm@linux-foundation.org> - 2016-03-08 00:00 +0100
      Re: [PATCH 1/1] dma-mapping: to avoid exception when cpu_addr is NULL "Leizhen (ThunderTown)" <thunder.leizhen@huawei.com> - 2016-03-08 02:40 +0100
  Re: [PATCH 1/1] dma-mapping: to avoid exception when cpu_addr is  NULL One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-03-07 12:50 +0100
    Re: [PATCH 1/1] dma-mapping: to avoid exception when cpu_addr is NULL "Leizhen (ThunderTown)" <thunder.leizhen@huawei.com> - 2016-03-07 13:30 +0100

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