[PATCH] drm/mm: fix dump table BUG

[Daniel Vetter]

In

commit 9e8944ab564f2e3dde90a518cd32048c58918608
Author: Chris Wilson <chris at 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.

Reported-by: Christopher Harvey <charvey at matrox.com>
Cc: Christopher Harvey <charvey at matrox.com>
Cc: Dave Airlie <airlied at redhat.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: stable at vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
---
 drivers/gpu/drm/drm_mm.c |   11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
index db1e2d6..a0ba3a1 100644
--- a/drivers/gpu/drm/drm_mm.c
+++ b/drivers/gpu/drm/drm_mm.c
@@ -759,14 +759,15 @@ 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;
+	unsigned long hole_start, hole_end, hole_size = 0;
 
-	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)
+	if (mm->head_node.hole_follows) {
+		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;
 		seq_printf(m, "0x%08lx-0x%08lx: 0x%08lx: free\n",
 				hole_start, hole_end, hole_size);
+	}
 	total_free += hole_size;
 
 	drm_mm_for_each_node(entry, mm) {
-- 
1.7.10.4