Re: [PATCH] pci-dma: Fix x86 dma_alloc_coherent to fully clear all pages returned
From: Tim Chen
Date: Wed Feb 18 2015 - 18:59:48 EST
On Wed, 2015-02-18 at 15:45 -0500, Alan Stern wrote:
> On Wed, 18 Feb 2015, Tim Chen wrote:
> > > Have you tried doing the experiments I suggested in
> > >
> > > http://marc.info/?l=linux-usb&m=142272448620716&w=2
> > >
> > > to determine where the problem occurs?
> > >
> > I was bogged down with other things lately and I haven't got a chance to
> > test that. But as you said, there's very few places where xhci
> > call this memory allocation. So I think the problem has been fairly
> > narrowed down for the XHCI folks.
> I disagree. _You_ reported the error. How can you expect other people
> to figure out where it is with no help from you?
> I looked briefly at the xhci-hcd DMA allocation code. It does not
> contain any obvious mistakes.
> Alan Stern
The error and my quick fix is right here. And xhci still needs to be
fixed properly. I'll send out the patch below in a proper patch.
diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index 5cb3d7a..39e7196 100644
@@ -1658,7 +1658,7 @@ static int scratchpad_alloc(struct xhci_hcd *xhci,
xhci->scratchpad->sp_array = dma_alloc_coherent(dev,
- num_sp * sizeof(u64),
+ PAGE_ALIGN(num_sp * sizeof(u64)),
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