Re: [PATCH] remove DMA_nBIT_MASK macro

[FUJITA Tomonori]

On Thu, 7 May 2009 13:18:46 +0200
Ingo Molnar <mingo@xxxxxxx> wrote:

> 
> * Yang Hongyang <yanghy@xxxxxxxxxxxxxx> wrote:
> 
> > FUJITA Tomonori wrote:
> > > We replaced all DMA_nBIT_MASK macros with DMA_BIT_MASK(n) but why do
> > > we still keep DMA_nBIT_MASK macros in include/linux/dma-mapping.h?
> > > 
> > > As long as these macros exist, people use them. The current git has
> > > two users and linux-next have other users.
> > > 
> > > Is it better to remove DMA_nBIT_MASK macros completely now?
> 
> Can you see a way to emit build warnings? If yes then that might be 
> a better solution instead of breaking in-the-pipeline code.

Unfortunately, no. Since 2.6.24, include/linux/dma-mapping.h has the
warning:

/*
 * NOTE: do not use the below macros in new code and do not add new definitions
 * here.
 *
 * Instead, just open-code DMA_BIT_MASK(n) within your driver
 */

IMO, we give people enough time for migration.


> We missed the upstream window of removing the facilities altogether,
> we could certainly do that in the next merge window though.

Can you apply this patch to the tip? I want to have this patch in
linux-next to let new users of DMA-nBIT_MASK in linux-next know that
they use wrong macros.
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