Currently, pci_mmap_legacy_page_range() reads the legacy resource
size from bus->legacy_mem->size or bus->legacy_io->size.  This
couples the mmap bounds check to the struct pci_bus fields that
will be removed when legacy attributes are converted to static
definitions.

Compute the size directly using PCI_LEGACY_MEM_SIZE (0x100000) and
PCI_LEGACY_IO_SIZE (0xffff) macros, and shift by 5 bits for sparse
systems.

Tested-by: Magnus Lindholm <[email protected]>
Tested-by: Shivaprasad G Bhat <[email protected]>
Acked-by: Magnus Lindholm <[email protected]>
Signed-off-by: Krzysztof Wilczyński <[email protected]>
---
 arch/alpha/kernel/pci-sysfs.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/alpha/kernel/pci-sysfs.c b/arch/alpha/kernel/pci-sysfs.c
index 20c97c06d755..89329910b890 100644
--- a/arch/alpha/kernel/pci-sysfs.c
+++ b/arch/alpha/kernel/pci-sysfs.c
@@ -174,8 +174,11 @@ int pci_mmap_legacy_page_range(struct pci_bus *bus, struct 
vm_area_struct *vma,
        int sparse = has_sparse(hose, mmap_type);
        unsigned long res_size;
 
-       res_size = (mmap_type == pci_mmap_mem) ? bus->legacy_mem->size :
-                                                bus->legacy_io->size;
+       res_size = (mmap_type == pci_mmap_mem) ? PCI_LEGACY_MEM_SIZE :
+                                                PCI_LEGACY_IO_SIZE;
+       if (sparse)
+               res_size <<= 5;
+
        if (!__legacy_mmap_fits(hose, vma, res_size))
                return -EINVAL;
 
-- 
2.54.0


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