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SubjectRe: BUG: NULL pointer dereference at 00000000 -- IP: [<f8e783d5>] :b43:b43_dma_mapping_error+0x16/0x155
On Tuesday 10 June 2008 16:42:41 Vegard Nossum wrote:
> This change comes from
> commit 353c409463ecba63c3a41a992d3f5fba935eada9
> Author: FUJITA Tomonori <>
> Date: Fri May 23 19:02:30 2008 +0000

Ok, FUJITA Tomonori, please make sure a patch like the following goes
into the same trees that you submitted commit 353c409 to.
Also make sure to check b43legacy. I _guess_ you might have added
the same bug there.

Index: wireless-testing/drivers/net/wireless/b43/dma.c
--- wireless-testing.orig/drivers/net/wireless/b43/dma.c 2008-06-10 13:58:22.000000000 +0200
+++ wireless-testing/drivers/net/wireless/b43/dma.c 2008-06-10 16:48:53.000000000 +0200
@@ -802,6 +802,7 @@ struct b43_dmaring *b43_setup_dmaring(st
if (!ring)
goto out;
ring->type = type;
+ ring->dev = dev;

nr_slots = B43_RXRING_SLOTS;
if (for_tx)
@@ -853,7 +854,6 @@ struct b43_dmaring *b43_setup_dmaring(st

- ring->dev = dev;
ring->nr_slots = nr_slots;
ring->mmio_base = b43_dmacontroller_base(type, controller_index);
ring->index = controller_index;

> dma-mapping-add-the-device-argument-to-dma_mapping_error
> Add per-device dma_mapping_ops support for CONFIG_X86_64 as POWER
> architecture does:
> This enables us to cleanly fix the Calgary IOMMU issue that some devices
> are not behind the IOMMU (
> I think that per-device dma_mapping_ops support would be also helpful for
> KVM people to support PCI passthrough but Andi thinks that this makes it
> difficult to support the PCI passthrough (see the above thread). So I
> CC'ed this to KVM camp. Comments are appreciated.
> A pointer to dma_mapping_ops to struct dev_archdata is added. If the
> pointer is non NULL, DMA operations in asm/dma-mapping.h use it. If it's
> NULL, the system-wide dma_ops pointer is used as before.
> If it's useful for KVM people, I plan to implement a mechanism to register
> a hook called when a new pci (or dma capable) device is created (it works
> with hot plugging). It enables IOMMUs to set up an appropriate
> dma_mapping_ops per device.
> The major obstacle is that dma_mapping_error doesn't take a pointer to the
> device unlike other DMA operations. So x86 can't have dma_mapping_ops per
> device. Note all the POWER IOMMUs use the same dma_mapping_error function
> so this is not a problem for POWER but x86 IOMMUs use different
> dma_mapping_error functions.
> The first patch adds the device argument to dma_mapping_error. The patch
> is trivial but large since it touches lots of drivers and dma-mapping.h in
> all the architecture.
> (Added to Cc.)
> Vegard

Greetings Michael.

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