Re: DMA debug trace pointing to rtl8187

["John W. Linville" <linville@tuxdriver.com>]

On Tue, May 05, 2009 at 11:45:13PM -0700, Greg KH wrote:
> On Wed, May 06, 2009 at 08:35:52AM +0200, Eric Valette wrote:
> > FUJITA Tomonori wrote:
> > > CC'ed linux-usb,
> > > 
> > > The ehci_hcd driver uses buffers on the stack for DMA?
> > > 
> > > On Sun, 03 May 2009 17:36:24 +0200
> > > Eric Valette <eric.valette@free.fr> wrote:
> > > 
> > >> ------------[ cut here ]------------
> > >>
> > >> WARNING: at /usr/src/linux-2.6.22.9/lib/dma-debug.c:609
> > > 
> > > Hmm, the kernel version is wired. lib/dma-debug.c was added in
> > > 2.6.30-rc.
> > 
> > No that's the file path.  I use ketchup to apply patches...
> > 
> > > 
> > >> check_for_stack+0x6b/0x8b()
> > >> Hardware name: P5W DH Deluxe
> > >>
> > >> ehci_hcd 0000:00:1d.7: DMA-API: device driver maps memory fromstack
> > >> [addr=ffff88007fa79968]
> > >> Modules linked in:
> > >>
> > >> Pid: 297, comm: khubd Not tainted 2.6.30-rc4-git1 #32
> > 
> > Here is the real version.
> 
> The problem is in the rtl8187 driver.
> 
> They are calling usb_control_msg and passing a pointer to a buffer on
> the stack.  See drivers/net/wireless/rtl818x/rtl8187.h for where the
> problem happens in numerous places.
> 
> Also it looks like rtl8225_write_8051() is incorrect.  You are passing a
> pointer to a variable that was passed as an argument.  I don't know
> where that is supposed to be on, somewhere on the stack I guess.
> 
> Larry, care to fix this up?

I just sent '[RFT] rtl8187: use DMA-aware buffers with usb_control_msg'
as a parallel reply to this message.  It is pretty ugly w.r.t. kmalloc
failures, but it might be worth testing just to see if it helps the
problem at hand...?

John
-- 
John W. Linville		Someday the world will need a hero, and you
linville@tuxdriver.com			might be all we have.  Be ready.