drm: make sure the drawable code doesn't call malloc(0).

Signed-off-by: Michel Dänzer <michel@tungstengraphics.com>
Signed-off-by: Dave Airlie <airlied@linux.ie>

1 files changed, 26 insertions, 15 deletions

diff --git a/drivers/char/drm/drm_drawable.c b/drivers/char/drm/drm_drawable.c
index de37d5f74563..b33313be2547 100644
--- a/drivers/char/drm/drm_drawable.c
+++ b/drivers/char/drm/drm_drawable.c
@@ -172,38 +172,49 @@ int drm_rmdraw(DRM_IOCTL_ARGS)
 
                 bitfield_length = idx + 1;
 
-                if (idx != id / (8 * sizeof(*bitfield)))
-                        bitfield = drm_alloc(bitfield_length *
-                                             sizeof(*bitfield), DRM_MEM_BUFS);
+                bitfield = NULL;
 
-                if (!bitfield && bitfield_length) {
-                        bitfield = dev->drw_bitfield;
-                        bitfield_length = dev->drw_bitfield_length;
+                if (bitfield_length) {
+                        if (bitfield_length != dev->drw_bitfield_length)
+                                bitfield = drm_alloc(bitfield_length *
+                                                     sizeof(*bitfield),
+                                                     DRM_MEM_BUFS);
+
+                        if (!bitfield) {
+                                bitfield = dev->drw_bitfield;
+                                bitfield_length = dev->drw_bitfield_length;
+                        }
                 }
         }
 
         if (bitfield != dev->drw_bitfield) {
                 info_length = 8 * sizeof(*bitfield) * bitfield_length;
 
-                info = drm_alloc(info_length * sizeof(*info), DRM_MEM_BUFS);
+                if (info_length) {
+                        info = drm_alloc(info_length * sizeof(*info),
+                                         DRM_MEM_BUFS);
 
-                if (!info && info_length) {
-                        info = dev->drw_info;
-                        info_length = dev->drw_info_length;
-                }
+                        if (!info) {
+                                info = dev->drw_info;
+                                info_length = dev->drw_info_length;
+                        }
+                } else
+                        info = NULL;
 
                 spin_lock_irqsave(&dev->drw_lock, irqflags);
 
-                memcpy(bitfield, dev->drw_bitfield, bitfield_length *
-                       sizeof(*bitfield));
+                if (bitfield)
+                        memcpy(bitfield, dev->drw_bitfield, bitfield_length *
+                               sizeof(*bitfield));
                 drm_free(dev->drw_bitfield, sizeof(*bitfield) *
                          dev->drw_bitfield_length, DRM_MEM_BUFS);
                 dev->drw_bitfield = bitfield;
                 dev->drw_bitfield_length = bitfield_length;
 
                 if (info != dev->drw_info) {
-                        memcpy(info, dev->drw_info, info_length *
-                               sizeof(*info));
+                        if (info)
+                                memcpy(info, dev->drw_info, info_length *
+                                       sizeof(*info));
                         drm_free(dev->drw_info, sizeof(*info) *
                                  dev->drw_info_length, DRM_MEM_BUFS);
                         dev->drw_info = info;