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usb; xhci: Fix TRB offset calculations.

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Greg KH introduced a bug into xhci_trb_virt_to_dma() when he changed the
type of offset to dma_addr_t from unsigned int and dropped the casts to
unsigned int around the virtual address pointer subtraction.

trb and seg->trbs are both valid pointers to virtual addresses, so the
compiler will mod the subtraction by the size of union trb (16 bytes).
segment_offset is an unsigned long, which is guaranteed to be at least as
big as a void *.

Drop the void * casts in the first if statement because trb and seg->trbs
are both pointers of the same type (pointers to union trb).

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Sarah Sharp 2009-05-14 11:44:14 -07:00 committed by Greg Kroah-Hartman
parent 7dd19e69d1
commit 6071d8363b
1 changed files with 6 additions and 7 deletions
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13
drivers/usb/host/xhci-ring.c
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@ -74,16 +74,15 @@
dma_addr_t xhci_trb_virt_to_dma(struct xhci_segment *seg,
union xhci_trb *trb)
{
dma_addr_t offset;
unsigned long segment_offset;
if (!seg || !trb || (void *) trb < (void *) seg->trbs)
if (!seg || !trb || trb < seg->trbs)
return 0;
/* offset in bytes, since these are byte-addressable */
offset = trb - seg->trbs;
/* SEGMENT_SIZE in bytes, trbs are 16-byte aligned */
if (offset > SEGMENT_SIZE || (offset % sizeof(*trb)) != 0)
/* offset in TRBs */
segment_offset = trb - seg->trbs;
if (segment_offset > TRBS_PER_SEGMENT)
return 0;
return seg->dma + offset;
return seg->dma + (segment_offset * sizeof(*trb));
}
/* Does this link TRB point to the first segment in a ring,