(+), 9 deletions(-)

diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index a61d38777cdc4..99086980e102e 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -1227,6 +1227,45 @@ static inline resource_size_t calculate_mem_align(resource_size_t *aligns,
 	return min_align;
 }
 
+/*
+ * Calculate bridge window head alignment that leaves no gaps in between
+ * resources.
+ */
+static resource_size_t calculate_head_align(resource_size_t *aligns,
+					    int max_order)
+{
+	resource_size_t head_align = 1;
+	resource_size_t remainder = 0;
+	int order;
+
+	/* Take the largest alignment as the starting point. */
+	head_align <<= max_order + __ffs(SZ_1M);
+
+	for (order = max_order - 1; order >= 0; order--) {
+		resource_size_t align1 = 1;
+
+		align1 <<= order + __ffs(SZ_1M);
+
+		/*
+		 * Account smaller resources with alignment < max_order that
+		 * could be used to fill head room if alignment less than
+		 * max_order is used.
+		 */
+		remainder += aligns[order];
+
+		/*
+		 * Test if head fill is enough to satisfy the alignment of
+		 * the larger resources after reducing the alignment.
+		 */
+		while ((head_align > align1) && (remainder >= head_align / 2)) {
+			head_align /= 2;
+			remainder -= head_align;
+		}
+	}
+
+	return head_align;
+}
+
 /**
  * pbus_upstream_space_available - Check no upstream resource limits allocation
  * @bus:	The bus
@@ -1314,13 +1353,13 @@ static void pbus_size_mem(struct pci_bus *bus, unsigned long type,
 {
 	struct pci_dev *dev;
 	resource_size_t min_align, win_align, align, size, size0, size1 = 0;
-	resource_size_t aligns[28]; /* Alignments from 1MB to 128TB */
+	resource_size_t aligns[28] = {}; /* Alignments from 1MB to 128TB */
+	resource_size_t aligns2[28] = {};/* Alignments from 1MB to 128TB */
 	int order, max_order;
 	struct resource *b_res = pbus_select_window_for_type(bus, type);
 	resource_size_t children_add_size = 0;
 	resource_size_t children_add_align = 0;
 	resource_size_t add_align = 0;
-	resource_size_t relaxed_align;
 	resource_size_t old_size;
 
 	if (!b_res)
@@ -1330,7 +1369,6 @@ static void pbus_size_mem(struct pci_bus *bus, unsigned long type,
 	if (b_res->parent)
 		return;
 
-	memset(aligns, 0, sizeof(aligns));
 	max_order = 0;
 	size = 0;
 
@@ -1381,6 +1419,7 @@ static void pbus_size_mem(struct pci_bus *bus, unsigned long type,
 			 */
 			if (r_size <= align)
 				aligns[order] += align;
+			aligns2[order] += align;
 			if (order > max_order)
 				max_order = order;
 
@@ -1405,9 +1444,7 @@ static void pbus_size_mem(struct pci_bus *bus, unsigned long type,
 
 	if (bus->self && size0 &&
 	    !pbus_upstream_space_available(bus, b_res, size0, min_align)) {
-		relaxed_align = 1ULL << (max_order + __ffs(SZ_1M));
-		relaxed_align = max(relaxed_align, win_align);
-		min_align = min(min_align, relaxed_align);
+		min_align = calculate_head_align(aligns2, max_order);
 		size0 = calculate_memsize(size, min_size, 0, 0, old_size, win_align);
 		resource_set_range(b_res, min_align, size0);
 		pci_info(bus->self, "bridge window %pR to %pR requires relaxed alignment rules\n",
@@ -1421,9 +1458,7 @@ static void pbus_size_mem(struct pci_bus *bus, unsigned long type,
 
 		if (bus->self && size1 &&
 		    !pbus_upstream_space_available(bus, b_res, size1, add_align)) {
-			relaxed_align = 1ULL << (max_order + __ffs(SZ_1M));
-			relaxed_align = max(relaxed_align, win_align);
-			min_align = min(min_align, relaxed_align);
+			min_align = calculate_head_align(aligns2, max_order);
 			size1 = calculate_memsize(size, min_size, add_size, children_add_size,
 						  old_size, win_align);
 			pci_info(bus->self,
-- 
2.51.0[PATCH 6.19 368/781] PCI: Rewrite bridge window head alignment functionGreg Kroah-Hartman <gregkh@linuxfoundation.org> undefinedstable@vger.kernel.org undefined undefined undefined undefined undefined undefined™†™<