Re: [PATCH -mm] replace DECLARE_DMA_UNMAP_ADD_{ADDR,LEN} with DEFINE_DMA_UNMAP_ADD_{ADDR,LEN}

[Randy Dunlap <rdunlap@xenotime.net>]

On 03/03/10 15:28, FUJITA Tomonori wrote:
> On Wed, 03 Mar 2010 15:16:05 -0800
> Randy Dunlap <rdunlap@xenotime.net> wrote:
> 
>> On 03/02/10 20:50, FUJITA Tomonori wrote:
>>> Seems that you missed the following patch?
>>>
>>> http://lkml.org/lkml/2010/2/13/2
>>>
>>> This can be fold into dma-mappingh-add-the-dma_unmap-state-api.patch.
>>>
>>> Thanks,
>>>
>>> =
>>> From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
>>> Subject: [PATCH -mm] replace DECLARE_DMA_UNMAP_ADD_{ADDR,LEN} with DEFINE_DMA_UNMAP_ADD_{ADDR,LEN}
>>>
>>> Andrew pointed out:
>>>
>>> - adding the semicolons at the end of DECLARE_DMA_UNMAP_{ADDR|LEN}
>>>   confuses people.
>>
>> Hm.  I'm (still) confused.  Why does this patch add semi-colons at the end
>> of DECLARE_PCI_UNMAP_{ADDR|LEN} below then?  (other than it is spelled with
>> letters "PCI" instead of "DMA")
> 
> Are you taking about this part, right?

Yes.

> +#define DECLARE_PCI_UNMAP_ADDR	(ADDR_NAME) DEFINE_DMA_UNMAP_ADDR(ADDR_NAME);
> +#define DECLARE_PCI_UNMAP_LEN(LEN_NAME)   DEFINE_DMA_UNMAP_LEN(LEN_NAME);
> 
> Currently, we have:
> 
> #define DECLARE_PCI_UNMAP_ADDR(ADDR_NAME)	dma_addr_t ADDR_NAME;
> 
> And PCI-DMA-mapping.txt says:
> 
> 	struct ring_state {
> 		struct sk_buff *skb;
> 		DECLARE_PCI_UNMAP_ADDR(mapping)
> 		DECLARE_PCI_UNMAP_LEN(len)
> 	};
> 
>    NOTE: DO NOT put a semicolon at the end of the DECLARE_*()
>          macro.

Argh.  That is just wrong.
Thanks for cleaning it all up.


> However, this confuses people. Some drivers already use this macro
> with a semicolon like, DECLARE_PCI_UNMAP_ADDR(mapping);
> 
> To avoid the above confusion, the new DEFINE_DMA_ macros doesn't have
> a semicolon (users need to use a semicolon):
> 
> #define DEFINE_DMA_UNMAP_ADDR(ADDR_NAME)        dma_addr_t ADDR_NAME
> #define DEFINE_DMA_UNMAP_LEN(LEN_NAME)          __u32 LEN_NAME
> 
> So we need to define DECLARE_PCI_* macro in the following way
> (otherwise we break the existing drivers):
> 
> #define DECLARE_PCI_UNMAP_ADDR	(ADDR_NAME) DEFINE_DMA_UNMAP_ADDR(ADDR_NAME);
> #define DECLARE_PCI_UNMAP_LEN(LEN_NAME)   DEFINE_DMA_UNMAP_LEN(LEN_NAME);
> 
> 
> In the long term, I'll remove DECLARE_PCI_* macros.

I see.  That's good, although I don't quite see the problem with doing
it all at once.


>>> - they are "definitions", not "declarations".
>>>
>>> Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
>>> ---
>>>  Documentation/DMA-API.txt   |    8 +++-----
>>>  include/linux/dma-mapping.h |    8 ++++----
>>>  include/linux/pci-dma.h     |   12 ++++++------
>>>  3 files changed, 13 insertions(+), 15 deletions(-)
>>>
>>> diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
>>> index d7d9eef..0fc5728 100644
>>> --- a/Documentation/DMA-API.txt
>>> +++ b/Documentation/DMA-API.txt
>>> @@ -494,7 +494,7 @@ portable API) the following facilities are provided.
>>>  Actually, instead of describing the macros one by one, we'll
>>>  transform some example code.
>>>  
>>> -1) Use DECLARE_DMA_UNMAP_{ADDR,LEN} in state saving structures.
>>> +1) Use DEFINE_DMA_UNMAP_{ADDR,LEN} in state saving structures.
>>>     Example, before:
>>>  
>>>  	struct ring_state {
>>> @@ -507,12 +507,10 @@ transform some example code.
>>>  
>>>  	struct ring_state {
>>>  		struct sk_buff *skb;
>>> -		DECLARE_DMA_UNMAP_ADDR(mapping)
>>> -		DECLARE_DMA_UNMAP_LEN(len)
>>> +		DEFINE_DMA_UNMAP_ADDR(mapping);
>>> +		DEFINE_DMA_UNMAP_LEN(len);
>>>  	};
>>>  
>>> -NOTE: DO NOT put a semicolon at the end of the DECLARE_*() macro.
>>> -
>>>  2) Use dma_unmap_{addr,len}_set to set these values.
>>>     Example, before:
>>>  
>>> diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
>>> index 599d8e4..e00c5c9 100644
>>> --- a/include/linux/dma-mapping.h
>>> +++ b/include/linux/dma-mapping.h
>>> @@ -241,15 +241,15 @@ struct dma_attrs;
>>>  #endif /* CONFIG_HAVE_DMA_ATTRS */
>>>  
>>>  #ifdef CONFIG_NEED_DMA_MAP_STATE
>>> -#define DECLARE_DMA_UNMAP_ADDR(ADDR_NAME)        dma_addr_t ADDR_NAME;
>>> -#define DECLARE_DMA_UNMAP_LEN(LEN_NAME)          __u32 LEN_NAME;
>>> +#define DEFINE_DMA_UNMAP_ADDR(ADDR_NAME)        dma_addr_t ADDR_NAME
>>> +#define DEFINE_DMA_UNMAP_LEN(LEN_NAME)          __u32 LEN_NAME
>>>  #define dma_unmap_addr(PTR, ADDR_NAME)           ((PTR)->ADDR_NAME)
>>>  #define dma_unmap_addr_set(PTR, ADDR_NAME, VAL)  (((PTR)->ADDR_NAME) = (VAL))
>>>  #define dma_unmap_len(PTR, LEN_NAME)             ((PTR)->LEN_NAME)
>>>  #define dma_unmap_len_set(PTR, LEN_NAME, VAL)    (((PTR)->LEN_NAME) = (VAL))
>>>  #else
>>> -#define DECLARE_DMA_MAP_ADDR(ADDR_NAME)
>>> -#define DECLARE_DMA_UNMAP_LEN(LEN_NAME)
>>> +#define DEFINE_DMA_MAP_ADDR(ADDR_NAME)
>>> +#define DEFINE_DMA_UNMAP_LEN(LEN_NAME)
>>>  #define dma_unmap_addr(PTR, ADDR_NAME)           (0)
>>>  #define dma_unmap_addr_set(PTR, ADDR_NAME, VAL)  do { } while (0)
>>>  #define dma_unmap_len(PTR, LEN_NAME)             (0)
>>> diff --git a/include/linux/pci-dma.h b/include/linux/pci-dma.h
>>> index 235a61e..549a041 100644
>>> --- a/include/linux/pci-dma.h
>>> +++ b/include/linux/pci-dma.h
>>> @@ -1,11 +1,11 @@
>>>  #ifndef _LINUX_PCI_DMA_H
>>>  #define _LINUX_PCI_DMA_H
>>>  
>>> -#define DECLARE_PCI_UNMAP_ADDR    DECLARE_DMA_UNMAP_ADDR
>>> -#define DECLARE_PCI_UNMAP_LEN     DECLARE_DMA_UNMAP_LEN
>>> -#define pci_unmap_addr            dma_unmap_addr
>>> -#define pci_unmap_addr_set        dma_unmap_addr_set
>>> -#define pci_unmap_len             dma_unmap_len
>>> -#define pci_unmap_len_set         dma_unmap_len_set
>>> +#define DECLARE_PCI_UNMAP_ADDR(ADDR_NAME) DEFINE_DMA_UNMAP_ADDR(ADDR_NAME);
>>> +#define DECLARE_PCI_UNMAP_LEN(LEN_NAME)   DEFINE_DMA_UNMAP_LEN(LEN_NAME);
>>> +#define pci_unmap_addr             dma_unmap_addr
>>> +#define pci_unmap_addr_set         dma_unmap_addr_set
>>> +#define pci_unmap_len              dma_unmap_len
>>> +#define pci_unmap_len_set          dma_unmap_len_set
>>>  
>>>  #endif


-- 
~Randy