Messages in this thread | | | Date | Tue, 20 Jan 2009 14:47:19 -0800 (PST) | Subject | Re: [PATCH] usb/mcs7830: Don't use buffers from stack for USB transfers | From | David Miller <> |
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From: Arnd Bergmann <arnd@arndb.de> Date: Tue, 20 Jan 2009 23:45:47 +0100
> On Tuesday 20 January 2009, you wrote: > > From: Christian Eggers <christian.eggers@kathrein.de> > > > > mcs7830_set_reg() and mcs7830_get_reg() are called with buffers > > from stack which must not be used directly for USB transfers. > > This causes corruption of the stack particulary on non x86 > > architectures because DMA may be used for these transfers. > > > > Signed-off-by: Christian Eggers <christian.eggers@kathrein.de> > > Have you observed problems with this, or just suspected trouble?
Yes, this is in response to SH platform failures.
You cannot DMA from/to the kernel stack, because it might not be in the aliased linear mapping of physical memory. It could even be vmalloc()'d memory on some platforms.
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