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PCI MSI: Fix undefined shift by 32
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Add an msi_mask() function which returns the correct bitmask for the
number of MSI interrupts you have.  This fixes an undefined bug in
msi_capability_init().

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
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Matthew Wilcox authored and Jesse Barnes committed Jan 27, 2009
1 parent 476e7fa commit bffac3c
Showing 1 changed file with 11 additions and 2 deletions.
13 changes: 11 additions & 2 deletions drivers/pci/msi.c
Original file line number Diff line number Diff line change
Expand Up @@ -103,6 +103,16 @@ 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];
}

static void msix_flush_writes(struct irq_desc *desc)
{
struct msi_desc *entry;
Expand Down Expand Up @@ -407,8 +417,7 @@ static int msi_capability_init(struct pci_dev *dev)

/* All MSIs are unmasked by default, Mask them all */
pci_read_config_dword(dev, base, &maskbits);
temp = (1 << multi_msi_capable(control));
temp = ((temp - 1) & ~temp);
temp = msi_mask((control & PCI_MSI_FLAGS_QMASK) >> 1);
maskbits |= temp;
pci_write_config_dword(dev, base, maskbits);
entry->msi_attrib.maskbits_mask = temp;
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