On Mon, Feb 09, 2009 at 10:40:55AM +0900, Hidetoshi Seto wrote:
> The commit bffac3c593eba1f9da3efd0199e49ea6558a40ce ("PCI MSI: Fix
> undefined shift by 32") does:
I think the commit message could be worded somewhat better, and I think
I should be credited as the author of the patch. How about this?
----
From: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>
Hidetoshi Seto points out that commit
bffac3c593eba1f9da3efd0199e49ea6558a40ce has wrong values in the
array. Rather than correct the array, we can just use a bounds check
and perform the calculation specified in the comment. As a bonus, this
will not run off the end of the array if the device specifies an illegal
value in the MSI capcbility.
Signed-off-by: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@xxxxxxxxxxxxxx>
----
drivers/pci/msi.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)
diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 44f15ff..baba2eb 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -103,14 +103,12 @@ static void msix_set_enable(struct pci_dev *dev, int enable)
}
}
-/*
- * Essentially, this is ((1 << (1 << x)) - 1), but without the
- * undefinedness of a << 32.
- */
static inline __attribute_const__ u32 msi_mask(unsigned x)
{
- static const u32 mask[] = { 1, 2, 4, 0xf, 0xff, 0xffff, 0xffffffff };
- return mask[x];
+ /* Don't shift by >= width of type */
+ if (x >= 5)
+ return 0xffffffff;
+ return (1 << (1 << x)) - 1;
}
static void msix_flush_writes(struct irq_desc *desc)
--
Matthew Wilcox Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours. We can't possibly take such
a retrograde step."
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