Merge branch 'linus' into x86/pebs

1 files changed, 27 insertions, 4 deletions

diff --git a/drivers/acpi/numa.c b/drivers/acpi/numa.c
index 5d59cb33b1a..658e5f3abae 100644
--- a/drivers/acpi/numa.c
+++ b/drivers/acpi/numa.c
@@ -140,19 +140,42 @@ acpi_table_print_srat_entry(struct acpi_subtable_header *header)
 	}
 }
 
+/*
+ * A lot of BIOS fill in 10 (= no distance) everywhere. This messes
+ * up the NUMA heuristics which wants the local node to have a smaller
+ * distance than the others.
+ * Do some quick checks here and only use the SLIT if it passes.
+ */
+static __init int slit_valid(struct acpi_table_slit *slit)
+{
+	int i, j;
+	int d = slit->locality_count;
+	for (i = 0; i < d; i++) {
+		for (j = 0; j < d; j++)  {
+			u8 val = slit->entry[d*i + j];
+			if (i == j) {
+				if (val != LOCAL_DISTANCE)
+					return 0;
+			} else if (val <= LOCAL_DISTANCE)
+				return 0;
+		}
+	}
+	return 1;
+}
+
 static int __init acpi_parse_slit(struct acpi_table_header *table)
 {
 	struct acpi_table_slit *slit;
-	u32 localities;
 
 	if (!table)
 		return -EINVAL;
 
 	slit = (struct acpi_table_slit *)table;
 
-	/* downcast just for %llu vs %lu for i386/ia64  */
-	localities = (u32) slit->locality_count;
-
+	if (!slit_valid(slit)) {
+		printk(KERN_INFO "ACPI: SLIT table looks invalid. Not used.\n");
+		return -EINVAL;
+	}
 	acpi_numa_slit_init(slit);
 
 	return 0;