lkml.org 
[lkml]   [2007]   [Jun]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] lib: Replace calls to __get_free_pages() with __get_dma_pages().
From
Date
On Wed, 2007-06-06 at 03:56 -0400, Robert P. J. Day wrote:
> On Tue, 5 Jun 2007, Andrew Morton wrote:
>
> > On Tue, 5 Jun 2007 16:58:57 -0400 (EDT)
> > "Robert P. J. Day" <rpjday@mindspring.com> wrote:
> >
> > > Replace a couple calls to __get_free_pages() with the corresponding
> > > calls to __get_dma_pages().
> > >
> > > Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
> > >
> > > ---
> > >
> > > that's the lot of them.
> > >
> > > diff --git a/lib/swiotlb.c b/lib/swiotlb.c
> > > index 10c13ad..8fc38dc 100644
> > > --- a/lib/swiotlb.c
> > > +++ b/lib/swiotlb.c
> > > @@ -201,8 +201,7 @@ swiotlb_late_init_with_default_size(size_t default_size)
> > > bytes = io_tlb_nslabs << IO_TLB_SHIFT;
> > >
> > > while ((SLABS_PER_PAGE << order) > IO_TLB_MIN_SLABS) {
> > > - io_tlb_start = (char *)__get_free_pages(GFP_DMA | __GFP_NOWARN,
> > > - order);
> > > + io_tlb_start = (char *)__get_dma_pages(__GFP_NOWARN, order);
> >
> > __get_dma_pages() is just pointless obfuscation. I think it'd be better to
> > go the other way: open-code the GFP_DMA at all callsites then send
> > __get_dma_pages() bitbucketwards.
>
> ok, it's easy enough to put together a patch that rids the tree of the
> superfluous __get_dma_pages() call. but in converting back to a call
> to __get_free_pages(), which of the two zone modifiers should be added
> -- "GFP_DMA" or "__GFP_DMA" -- since they're currently defined
> equivalently in include/linux/gfp.h. and there's definitely a mixture
> of usage in the tree at the moment:
>
> $ grep -r "get_free.*GFP_DMA" *
> arch/s390/kernel/smp.c: __get_free_pages(GFP_KERNEL | GFP_DMA,
> drivers/net/arm/ep93xx_eth.c: page = (void *)__get_free_page(GFP_KERNEL | GFP_DMA);
> drivers/net/arm/ep93xx_eth.c: page = (void *)__get_free_page(GFP_KERNEL | GFP_DMA);
> drivers/s390/net/qeth_main.c: ptr = (void *) __get_free_page(GFP_KERNEL|GFP_DMA);
> drivers/s390/net/claw.c: (void *)__get_free_pages(__GFP_DMA,
> drivers/s390/net/claw.c: (void *)__get_free_pages(__GFP_DMA,
> drivers/s390/net/claw.c: p_buff=(void *)__get_free_pages(__GFP_DMA,
> drivers/s390/net/claw.c: (void *)__get_free_pages(__GFP_DMA,
> drivers/s390/net/claw.c: p_buff = (void *)__get_free_pages(__GFP_DMA,
> drivers/s390/block/dasd.c: device->ccw_mem = (void *) __get_free_pages(GFP_ATOMIC | GFP_DMA, 1);
> drivers/s390/char/tty3270.c: __get_free_pages(GFP_KERNEL|GFP_DMA, 0);
> drivers/s390/char/sclp_cpi.c: sccb = (struct cpi_sccb *) __get_free_page(GFP_KERNEL | GFP_DMA);
> drivers/s390/cio/cmf.c: mem = (void*)__get_free_pages(GFP_KERNEL | GFP_DMA,
> include/linux/gfp.h: __get_free_pages((gfp_mask) | GFP_DMA,(order))
> lib/swiotlb.c: io_tlb_start = (char *)__get_free_pages(GFP_DMA | __GFP_NOWARN,
> lib/swiotlb.c: io_tlb_overflow_buffer = (void *)__get_free_pages(GFP_DMA,
>
> i'm guessing "GFP_DMA" would be the right choice, which means that,
> for consistency, the calls using __GFP_DMA should be switched over as
> well. guidance, anyone?

FWIW I prefer:

GFP_KERNEL | __GFP_DMA
GFP_ATOMIC | __GFP_DMA
and

GFP_DMA

That is, when used as a modifier use __GFP_, when used as a class use
GFP_.

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-06-06 10:27    [from the cache]
©2003-2011 Jasper Spaans