intel-gem: Fix pread math and logic errors.

Fixes an oops in fbotexture from walking off the end of the page list.

diff --git a/linux-core/i915_gem.c b/linux-core/i915_gem.c
index db068ce..e469742 100644 (file)
--- a/linux-core/i915_gem.c
+++ b/linux-core/i915_gem.c
@@ -169,20 +169,16 @@ i915_gem_pread_ioctl(struct drm_device *dev, void *data,
                }
        }
        if ((obj->read_domains & I915_GEM_DOMAIN_CPU) == 0) {
-               int got_page_list = 0;
                int first_page = args->offset / PAGE_SIZE;
-               int last_page = (args->offset + args->size) / PAGE_SIZE;
+               int last_page = (args->offset + args->size - 1) / PAGE_SIZE;
 
-               if (obj_priv->page_list == NULL) {
-                       i915_gem_object_get_page_list(obj);
-                       got_page_list = 1;
-               }
+               /* If we don't have the page list, the pages are unpinned
+                * and swappable, and thus should already be in the CPU domain.
+                */
+               BUG_ON(obj_priv->page_list == NULL);
 
                drm_ttm_cache_flush(&obj_priv->page_list[first_page],
                                    last_page - first_page + 1);
-
-               if (got_page_list)
-                       i915_gem_object_free_page_list(obj);
        }
 
        offset = args->offset;