Allocate from the end of a region, not the beginning.
For example, if we need to allocate 0x800 bytes for a device on bus
0000:00 given these resources:
[mem 0xbff00000-0xdfffffff] PCI Bus 0000:00
[mem 0xc0000000-0xdfffffff] PCI Bus 0000:02
the available space at [mem 0xbff00000-0xbfffffff] is passed to the
alignment callback (pcibios_align_resource()). Prior to this patch, we
would put the new 0x800 byte resource at the beginning of that available
space, i.e., at [mem 0xbff00000-0xbff007ff].
With this patch, we put it at the end, at [mem 0xbffff800-0xbfffffff].
Reference: https://bugzilla.kernel.org/show_bug.cgi?id=16228#c41
Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
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