drm/mm: fix dump table BUG

In

commit 9e8944ab56
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Thu Nov 15 11:32:17 2012 +0000

    drm: Introduce an iterator over holes in the drm_mm range manager

helpers and iterators for hole handling have been introduced with some
debug BUG_ONs sprinkled over. Unfortunately this broke the mm dumper
which unconditionally tried to compute the size of the very first
hole.

While at it unify the code a bit with the hole dumping in the loop.

v2: Extract a hole dump helper.

Reported-by: Christopher Harvey <charvey@matrox.com>
Cc: Christopher Harvey <charvey@matrox.com>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: stable@vger.kernel.org
Acked-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/drm_mm.c

@@ -755,33 +755,35 @@ void drm_mm_debug_table(struct drm_mm *mm, const char *prefix)
 EXPORT_SYMBOL(drm_mm_debug_table);
 
 #if defined(CONFIG_DEBUG_FS)
+static unsigned long drm_mm_dump_hole(struct seq_file *m, struct drm_mm_node *entry)
+{
+	unsigned long hole_start, hole_end, hole_size;
+
+	if (entry->hole_follows) {
+		hole_start = drm_mm_hole_node_start(entry);
+		hole_end = drm_mm_hole_node_end(entry);
+		hole_size = hole_end - hole_start;
+		seq_printf(m, "0x%08lx-0x%08lx: 0x%08lx: free\n",
+				hole_start, hole_end, hole_size);
+		return hole_size;
+	}
+
+	return 0;
+}
+
 int drm_mm_dump_table(struct seq_file *m, struct drm_mm *mm)
 {
 	struct drm_mm_node *entry;
 	unsigned long total_used = 0, total_free = 0, total = 0;
-	unsigned long hole_start, hole_end, hole_size;
 
-	hole_start = drm_mm_hole_node_start(&mm->head_node);
-	hole_end = drm_mm_hole_node_end(&mm->head_node);
-	hole_size = hole_end - hole_start;
-	if (hole_size)
-		seq_printf(m, "0x%08lx-0x%08lx: 0x%08lx: free\n",
-				hole_start, hole_end, hole_size);
-	total_free += hole_size;
+	total_free += drm_mm_dump_hole(m, &mm->head_node);
 
 	drm_mm_for_each_node(entry, mm) {
 		seq_printf(m, "0x%08lx-0x%08lx: 0x%08lx: used\n",
 				entry->start, entry->start + entry->size,
 				entry->size);
 		total_used += entry->size;
-		if (entry->hole_follows) {
-			hole_start = drm_mm_hole_node_start(entry);
-			hole_end = drm_mm_hole_node_end(entry);
-			hole_size = hole_end - hole_start;
-			seq_printf(m, "0x%08lx-0x%08lx: 0x%08lx: free\n",
-					hole_start, hole_end, hole_size);
-			total_free += hole_size;
-		}
+		total_free += drm_mm_dump_hole(m, entry);
 	}
 	total = total_free + total_used;