lkml.org 
[lkml]   [2007]   [Apr]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH] dma_declare_coherent_memory wrong allocation
On Sat, 21 Apr 2007, Andrew Morton wrote:

> On Fri, 13 Apr 2007 20:08:28 +0200 (CEST) Guennadi Liakhovetski <g.liakhovetski@gmx.de> wrote:
>
> > Hi
> >
> > Either I've finally gone blind on this Friday 13th or... Looks like this
> > almost 3 year old function has a bug. Patch below compile-tested... in a
> > way.

[patch skipped]

> Looks that way to me, too.

Then I'll dare suggest arch/cris - the second and last arch implementing
this API - has the same problem. Maintainer added to cc:, patch below.

> It also hopes like hell that `size' was a multiple of PAGE_SIZE.

Well, this API seems to have a bigger problem: it is difficult to get to
SoC/bus-local memory from several child devices. Even if I do implement
that DMA_MEMORY_INCLUDES_CHILDREN flag, 1) you do not always have the
desired device as your immediate parent, 2) you have to ref-count it. For
example, I was trying to use SoC-local SRAM on PXA270 from the
framebuffer, but fb-devices on PXA are either platform devices, or
sometimes get other parents. So, looks like another way to get to the SoC
node is needed...

Thanks
Guennadi
---
Guennadi Liakhovetski

Fix dma_declare_coherent_memory wrong allocation for cris/arch-v32

arch/cris/arch-v32 seems to have copy-pasted the bug from arch/i386 fixed
with an earlier patch - allocate bitmap in bytes, not words.

Signed-off-by: G. Liakhovetski <g.liakhovetski@gmx.de>

diff --git a/arch/cris/arch-v32/drivers/pci/dma.c b/arch/cris/arch-v32/drivers/pci/dma.c
index 70d3bf0..d634347 100644
--- a/arch/cris/arch-v32/drivers/pci/dma.c
+++ b/arch/cris/arch-v32/drivers/pci/dma.c
@@ -76,7 +76,7 @@ int dma_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr,
{
void __iomem *mem_base;
int pages = size >> PAGE_SHIFT;
- int bitmap_size = (pages + 31)/32;
+ int bitmap_size = DIV_ROUND_UP(pages, 8);

if ((flags & (DMA_MEMORY_MAP | DMA_MEMORY_IO)) == 0)
goto out;
-
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: 2007-04-21 13:05    [W:0.104 / U:0.884 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site