This
works fine as long as there are enough resources  to satisfy all other
genuine resource requirements. However if enough resources are not
available to satisfy any of these nice-to-have pre-allocations, the
resource-allocator reports errors and returns failure.

This patch distinguishes between must-have resource from nice-to-have
resource.  Any failure to allocate nice-to-have resources are ignored.

This behavior can be particularly useful to trigger automatic
reallocation when the OS discovers genuine allocation-conflicts or
genuine unallocated-requests caused by buggy allocation behavior of the
native BIOS/uEFI.

https://bugzilla.kernel.org/show_bug.cgi?id=15960 captures the
movitation behind the patch. This patch is verified to resolve the above
bug.

    changelog v2:  o  fixed a bug where pci_assign_resource() was called on a
    		  resource of zero resource size.

    changelog v3:  addressed Bjorn's comment
    	       o  "Please don't indent and right-justify the changelog".
    	       o  removed add_size from struct resource.  The additional
    		  size is now tracked using a linked list.

    changelog v4:  o moved freeing up of elements in head list from
    		assign_requested_resources_sorted() to
    		__assign_resources_sorted().
    	       o removed a wrong reference to 'add_size' in
    			pbus_size_mem().
    	       o some code optimizations in adjust_resources_sorted()
    			and assign_requested_resources_sorted()

    changelog v5:  o moved freeing up of elements in head list from
    		assign_requested_resources_sorted() to
    		__assign_resources_sorted().
    	       o removed a wrong reference to 'add_size' in
    			pbus_size_mem().
    	       o some code optimizations in adjust_resources_sorted()
    			and assign_requested_resources_sorted()

    changelog v5:  o factored out common code and made them into
		separate independent patches
    	       o added comments in kdoc format
	       o added a BUG_ON in pci_assign_unassigned_resources()
		 to catch for memory leak.

Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>