[PATCH 2/8] [I/OAT] Driver for the Intel(R) I/OAT DMA engine

[PATCH 2/8] [I/OAT] Driver for the Intel(R) I/OAT DMA engine

[Leech, Christopher]

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From: Chris Leech [mailto:christopher.leech@intel.com] 
Sent: Friday, March 10, 2006 6:29 PM
To: 
Subject: [PATCH 2/8] [I/OAT] Driver for the Intel(R) I/OAT DMA engine


Adds a new ioatdma driver

Signed-off-by: Chris Leech <christopher.leech@intel.com>
---

 drivers/dma/Kconfig             |    9 
 drivers/dma/Makefile            |    1 
 drivers/dma/ioatdma.c           |  783
+++++++++++++++++++++++++++++++++++++++
 drivers/dma/ioatdma.h           |  127 ++++++
 drivers/dma/ioatdma_hw.h        |   52 +++
 drivers/dma/ioatdma_io.h        |  104 +++++
 drivers/dma/ioatdma_registers.h |  128 ++++++
 7 files changed, 1204 insertions(+), 0 deletions(-)


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Re: [PATCH 2/8] [I/OAT] Driver for the Intel(R) I/OAT DMA engine

[Evgeniy Polyakov]

On Fri, Mar 10, 2006 at 06:29:46PM -0800, Leech, Christopher (christopher.leech@intel.com) wrote:
> From: Chris Leech [mailto:christopher.leech@intel.com] 
> Sent: Friday, March 10, 2006 6:29 PM
> To: 
> Subject: [PATCH 2/8] [I/OAT] Driver for the Intel(R) I/OAT DMA engine
> 
> 
> Adds a new ioatdma driver

enumerate_dma_channels() is still broken, if it can not fail add NOFAIL
gfp flag.
And you play tricky games with common_node/device_node of struct
dma_chan - one of that lists is never protected, while other is called 
under RCU and other locks (btw, why does insertion use RCU and deletion
in dma_async_device_unregister() does not?).
struct ioat_dma_chan - is it somewhere freed?

-- 
	Evgeniy Polyakov

Re: [PATCH 2/8] [I/OAT] Driver for the Intel(R) I/OAT DMA engine

[Andrew Morton]

Evgeniy Polyakov <johnpol@2ka.mipt.ru> wrote:
>
>  On Fri, Mar 10, 2006 at 06:29:46PM -0800, Leech, Christopher (christopher.leech@intel.com) wrote:
>  > From: Chris Leech [mailto:christopher.leech@intel.com] 
>  > Sent: Friday, March 10, 2006 6:29 PM
>  > To: 
>  > Subject: [PATCH 2/8] [I/OAT] Driver for the Intel(R) I/OAT DMA engine
>  > 
>  > 
>  > Adds a new ioatdma driver
> 
>  enumerate_dma_channels() is still broken, if it can not fail add NOFAIL
>  gfp flag.

The __GFP_NOFAIL flag is there to mark lame-and-buggy-code which doesn't
know how to handle ENOMEM.  I went through the kernel, found all the
retry-until-it-works loops and consolidated their behaviour in the page
allocator instead.

Really we should fix them all up.  Adding new users of __GFP_NOFAIL
would not be good.