On 08/05/13 10:53, Stephen Warren wrote:
From: Stephen Warren <swarren@xxxxxxxxxx>
Many USB host drivers contain code such as:
if (!pdev->dev.dma_mask)
pdev->dev.dma_mask = &tegra_ehci_dma_mask;
... where tegra_ehci_dma_mask is a global. I suspect this code originated
in commit 4a53f4e "USB: ehci-tegra: add probing through device tree" and
was simply copied everywhere else.
This works fine when the code is built-in, but can cause a crash when the
code is in a module. The first module load sets up the dma_mask pointer,
but if the module is removed and re-inserted, the value is now non-NULL,
and hence is not updated to point at the new location, and hence points
at a stale location within the previous module load address, which in
turn causes a crash if the pointer is de-referenced.
The simplest way of solving this seems to be to copy the code from
ehci-platform.c, which uses the coherent_dma_mask as the target for the
dma_mask pointer.
Suggested-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Stephen Warren <swarren@xxxxxxxxxx>
---
In the case of uhci-platform you would be absolutely correct. I copied the
example from tegra when we first had the problem on arch-vt8500.Because we
have no NAND support yet, I have always booted myrootfs from USB so it's
always been builtin and the problem wasnever a problem. The same problem
would
have existed on ehci-vt8500 but Arnd replaced it with ehci-platform due to
the multiplatform issues.
for uhci-platform.c
Acked-by: Tony Prisk <linux@xxxxxxxxxxxxxxx>
Regards
Tony P
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