linux-kernel - Re: [PATCH 5/7] swiotlb: (re)Create swiotlb_unmap

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Message-Id: <726BF449-4F7A-472D-AC5A-D8218B61210B@kernel.crashing.org>
Date:	Tue, 7 Apr 2009 12:32:12 -0500
From:	Kumar Gala <galak@...nel.crashing.org>
To:	FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
Cc:	beckyb@...nel.crashing.org, linux-kernel@...r.kernel.org,
	mingo@...e.hu, jeremy@...p.org, ian.campbell@...rix.com
Subject: Re: [PATCH 5/7] swiotlb: (re)Create swiotlb_unmap_single


On Apr 7, 2009, at 12:22 PM, FUJITA Tomonori wrote:

> On Tue, 7 Apr 2009 11:50:56 -0500
> Kumar Gala <galak@...nel.crashing.org> wrote:
>
>>
>> On Apr 7, 2009, at 11:37 AM, FUJITA Tomonori wrote:
>>
>>> On Tue, 7 Apr 2009 10:32:20 -0500
>>> Kumar Gala <galak@...nel.crashing.org> wrote:
>>>
>>>>
>>>> On Apr 7, 2009, at 4:09 AM, FUJITA Tomonori wrote:
>>>>
>>>>> On Tue, 7 Apr 2009 01:34:44 -0500
>>>>> Kumar Gala <galak@...nel.crashing.org> wrote:
>>>>>
>>>>>>
>>>>>> On Apr 6, 2009, at 9:24 PM, FUJITA Tomonori wrote:
>>>>>>
>>>>>>> On Fri,  3 Apr 2009 20:56:47 -0500
>>>>>>> Becky Bruce <beckyb@...nel.crashing.org> wrote:
>>>>>>>
>>>>>>>> This mirrors the current swiotlb_sync_single() setup
>>>>>>>> where the swiotlb_unmap_single() function is static to this
>>>>>>>> file and contains the logic required to determine if we need
>>>>>>>> to call actual sync_single.  Previously, swiotlb_unmap_page
>>>>>>>> and swiotlb_unmap_sg were duplicating very similar code.
>>>>>>>> The duplicated code has also been reformatted for
>>>>>>>> readability.
>>>>>>>>
>>>>>>>> Note that the swiotlb_unmap_sg code was previously doing
>>>>>>>> a complicated comparison to determine if an addresses needed
>>>>>>>> to be unmapped where a simple is_swiotlb_buffer() call
>>>>>>>> would have sufficed.
>>>>>>>>
>>>>>>>> Signed-off-by: Becky Bruce <beckyb@...nel.crashing.org>
>>>>>>>> ---
>>>>>>>> lib/swiotlb.c |   36 +++++++++++++++++++++++-------------
>>>>>>>> 1 files changed, 23 insertions(+), 13 deletions(-)
>>>>>>>>
>>>>>>>> diff --git a/lib/swiotlb.c b/lib/swiotlb.c
>>>>>>>> index af2ec25..602315b 100644
>>>>>>>> --- a/lib/swiotlb.c
>>>>>>>> +++ b/lib/swiotlb.c
>>>>>>>
>>>>>>> I don't think 'swiotlb_unmap_single' name is appropriate.
>>>>>>>
>>>>>>> swiotlb_unmap_single sounds like an exported function that  
>>>>>>> IOMMUs
>>>>>>> can
>>>>>>> use (and it was) however it should not be.
>>>>>>
>>>>>> What do you suggest we call it?  __swiotlb_unmap_single.
>>>>>
>>>>> I think that __swiotlb_unmap_single is better because the name
>>>>> implies
>>>>> that it's an internal function. It's fine by me.
>>>>>
>>>>> If it is odd that __swiotlb_unmap_single() is just a wrapper
>>>>> function
>>>>> of unmap_single(), which does the real job to unmap a dma mapping,
>>>>> it
>>>>> might be another possible option to rename unmap_single to
>>>>> do_unamp_single and use unmap_single.
>>>>
>>>> I think you lost me here.  I'd prefer to just use
>>>> __swiotlb_unmap_single at this point and get this code into the  
>>>> tree
>>>> and work on such renaming after the fact (if that's ok).
>>>
>>> If you are rushing to merge this right now, the original patchset is
>>> fine by me (I thought that you missed this merge window). I'll  
>>> rename
>>> it later.
>>
>> We probably did, but one can never tell with these things.  It seemed
>> like Ingo merged and pushed some swiotlb changes late in the game  
>> for .
>> 29
>
> Well, merging patches that have not been tested linux-next late is
> what we should not do, I guess. I like to see Becky's patch in 2.6.30
> because I have some swiotlb changes for 2.6.31 though.

Same here.  It makes it easier for us to work on the powerpc arch  
specific changes for .31 if we can get these into .30.  What are you  
looking at for .31?

Ingo, any comments on that?

>> I'm still not clear on what you are suggesting... "rename  
>> unmap_single
>> to do_unamp_single and use unmap_single".
>
> This can be applied after Becky's patchset.

thanks. I'll merge this into her patch set and repost it.

- k
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