drm/i915: Make GEM object's page lists refcounted instead of get/free.

We've wanted this for a few consumers that touch the pages directly (such as
the following commit), which have been doing the refcounting outside of
get/put pages.

Signed-off-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>

2 files changed, 38 insertions, 35 deletions

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index d6cc9861e0a1..75e33844146b 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -404,7 +404,8 @@ struct drm_i915_gem_object {
         /** AGP memory structure for our GTT binding. */
         DRM_AGP_MEM *agp_mem;
 
-        struct page **page_list;
+        struct page **pages;
+        int pages_refcount;
 
         /**
          * Current offset of the object in GTT space.
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 35f8c7bd0d32..b998d659fd98 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -43,8 +43,8 @@ static int i915_gem_object_set_cpu_read_domain_range(struct drm_gem_object *obj,
                                                      uint64_t offset,
                                                      uint64_t size);
 static void i915_gem_object_set_to_full_cpu_read_domain(struct drm_gem_object *obj);
-static int i915_gem_object_get_page_list(struct drm_gem_object *obj);
-static void i915_gem_object_free_page_list(struct drm_gem_object *obj);
+static int i915_gem_object_get_pages(struct drm_gem_object *obj);
+static void i915_gem_object_put_pages(struct drm_gem_object *obj);
 static int i915_gem_object_wait_rendering(struct drm_gem_object *obj);
 static int i915_gem_object_bind_to_gtt(struct drm_gem_object *obj,
                                            unsigned alignment);
@@ -928,29 +928,30 @@ i915_gem_mmap_gtt_ioctl(struct drm_device *dev, void *data,
 }
 
 static void
-i915_gem_object_free_page_list(struct drm_gem_object *obj)
+i915_gem_object_put_pages(struct drm_gem_object *obj)
 {
         struct drm_i915_gem_object *obj_priv = obj->driver_private;
         int page_count = obj->size / PAGE_SIZE;
         int i;
 
-        if (obj_priv->page_list == NULL)
-                return;
+        BUG_ON(obj_priv->pages_refcount == 0);
 
+        if (--obj_priv->pages_refcount != 0)
+                return;
 
         for (i = 0; i < page_count; i++)
-                if (obj_priv->page_list[i] != NULL) {
+                if (obj_priv->pages[i] != NULL) {
                         if (obj_priv->dirty)
-                                set_page_dirty(obj_priv->page_list[i]);
-                        mark_page_accessed(obj_priv->page_list[i]);
-                        page_cache_release(obj_priv->page_list[i]);
+                                set_page_dirty(obj_priv->pages[i]);
+                        mark_page_accessed(obj_priv->pages[i]);
+                        page_cache_release(obj_priv->pages[i]);
                 }
         obj_priv->dirty = 0;
 
-        drm_free(obj_priv->page_list,
+        drm_free(obj_priv->pages,
                  page_count * sizeof(struct page *),
                  DRM_MEM_DRIVER);
-        obj_priv->page_list = NULL;
+        obj_priv->pages = NULL;
 }
 
 static void
@@ -1402,7 +1403,7 @@ i915_gem_object_unbind(struct drm_gem_object *obj)
         if (obj_priv->fence_reg != I915_FENCE_REG_NONE)
                 i915_gem_clear_fence_reg(obj);
 
-        i915_gem_object_free_page_list(obj);
+        i915_gem_object_put_pages(obj);
 
         if (obj_priv->gtt_space) {
                 atomic_dec(&dev->gtt_count);
@@ -1521,7 +1522,7 @@ i915_gem_evict_everything(struct drm_device *dev)
 }
 
 static int
-i915_gem_object_get_page_list(struct drm_gem_object *obj)
+i915_gem_object_get_pages(struct drm_gem_object *obj)
 {
         struct drm_i915_gem_object *obj_priv = obj->driver_private;
         int page_count, i;
@@ -1530,18 +1531,19 @@ i915_gem_object_get_page_list(struct drm_gem_object *obj)
         struct page *page;
         int ret;
 
-        if (obj_priv->page_list)
+        if (obj_priv->pages_refcount++ != 0)
                 return 0;
 
         /* Get the list of pages out of our struct file.  They'll be pinned
          * at this point until we release them.
          */
         page_count = obj->size / PAGE_SIZE;
-        BUG_ON(obj_priv->page_list != NULL);
-        obj_priv->page_list = drm_calloc(page_count, sizeof(struct page *),
-                                         DRM_MEM_DRIVER);
-        if (obj_priv->page_list == NULL) {
+        BUG_ON(obj_priv->pages != NULL);
+        obj_priv->pages = drm_calloc(page_count, sizeof(struct page *),
+                                     DRM_MEM_DRIVER);
+        if (obj_priv->pages == NULL) {
                 DRM_ERROR("Faled to allocate page list\n");
+                obj_priv->pages_refcount--;
                 return -ENOMEM;
         }
 
@@ -1552,10 +1554,10 @@ i915_gem_object_get_page_list(struct drm_gem_object *obj)
                 if (IS_ERR(page)) {
                         ret = PTR_ERR(page);
                         DRM_ERROR("read_mapping_page failed: %d\n", ret);
-                        i915_gem_object_free_page_list(obj);
+                        i915_gem_object_put_pages(obj);
                         return ret;
                 }
-                obj_priv->page_list[i] = page;
+                obj_priv->pages[i] = page;
         }
         return 0;
 }
@@ -1878,7 +1880,7 @@ i915_gem_object_bind_to_gtt(struct drm_gem_object *obj, unsigned alignment)
         DRM_INFO("Binding object of size %d at 0x%08x\n",
                  obj->size, obj_priv->gtt_offset);
 #endif
-        ret = i915_gem_object_get_page_list(obj);
+        ret = i915_gem_object_get_pages(obj);
         if (ret) {
                 drm_mm_put_block(obj_priv->gtt_space);
                 obj_priv->gtt_space = NULL;
@@ -1890,12 +1892,12 @@ i915_gem_object_bind_to_gtt(struct drm_gem_object *obj, unsigned alignment)
          * into the GTT.
          */
         obj_priv->agp_mem = drm_agp_bind_pages(dev,
-                                               obj_priv->page_list,
+                                               obj_priv->pages,
                                                page_count,
                                                obj_priv->gtt_offset,
                                                obj_priv->agp_type);
         if (obj_priv->agp_mem == NULL) {
-                i915_gem_object_free_page_list(obj);
+                i915_gem_object_put_pages(obj);
                 drm_mm_put_block(obj_priv->gtt_space);
                 obj_priv->gtt_space = NULL;
                 return -ENOMEM;
@@ -1922,10 +1924,10 @@ i915_gem_clflush_object(struct drm_gem_object *obj)
          * to GPU, and we can ignore the cache flush because it'll happen
          * again at bind time.
          */
-        if (obj_priv->page_list == NULL)
+        if (obj_priv->pages == NULL)
                 return;
 
-        drm_clflush_pages(obj_priv->page_list, obj->size / PAGE_SIZE);
+        drm_clflush_pages(obj_priv->pages, obj->size / PAGE_SIZE);
 }
 
 /** Flushes any GPU write domain for the object if it's dirty. */
@@ -2270,7 +2272,7 @@ i915_gem_object_set_to_full_cpu_read_domain(struct drm_gem_object *obj)
                 for (i = 0; i <= (obj->size - 1) / PAGE_SIZE; i++) {
                         if (obj_priv->page_cpu_valid[i])
                                 continue;
-                        drm_clflush_pages(obj_priv->page_list + i, 1);
+                        drm_clflush_pages(obj_priv->pages + i, 1);
                 }
                 drm_agp_chipset_flush(dev);
         }
@@ -2336,7 +2338,7 @@ i915_gem_object_set_cpu_read_domain_range(struct drm_gem_object *obj,
                 if (obj_priv->page_cpu_valid[i])
                         continue;
 
-                drm_clflush_pages(obj_priv->page_list + i, 1);
+                drm_clflush_pages(obj_priv->pages + i, 1);
 
                 obj_priv->page_cpu_valid[i] = 1;
         }
@@ -3304,7 +3306,7 @@ i915_gem_init_hws(struct drm_device *dev)
 
         dev_priv->status_gfx_addr = obj_priv->gtt_offset;
 
-        dev_priv->hw_status_page = kmap(obj_priv->page_list[0]);
+        dev_priv->hw_status_page = kmap(obj_priv->pages[0]);
         if (dev_priv->hw_status_page == NULL) {
                 DRM_ERROR("Failed to map status page.\n");
                 memset(&dev_priv->hws_map, 0, sizeof(dev_priv->hws_map));
@@ -3334,7 +3336,7 @@ i915_gem_cleanup_hws(struct drm_device *dev)
         obj = dev_priv->hws_obj;
         obj_priv = obj->driver_private;
 
-        kunmap(obj_priv->page_list[0]);
+        kunmap(obj_priv->pages[0]);
         i915_gem_object_unpin(obj);
         drm_gem_object_unreference(obj);
         dev_priv->hws_obj = NULL;
@@ -3637,20 +3639,20 @@ void i915_gem_detach_phys_object(struct drm_device *dev,
         if (!obj_priv->phys_obj)
                 return;
 
-        ret = i915_gem_object_get_page_list(obj);
+        ret = i915_gem_object_get_pages(obj);
         if (ret)
                 goto out;
 
         page_count = obj->size / PAGE_SIZE;
 
         for (i = 0; i < page_count; i++) {
-                char *dst = kmap_atomic(obj_priv->page_list[i], KM_USER0);
+                char *dst = kmap_atomic(obj_priv->pages[i], KM_USER0);
                 char *src = obj_priv->phys_obj->handle->vaddr + (i * PAGE_SIZE);
 
                 memcpy(dst, src, PAGE_SIZE);
                 kunmap_atomic(dst, KM_USER0);
         }
-        drm_clflush_pages(obj_priv->page_list, page_count);
+        drm_clflush_pages(obj_priv->pages, page_count);
         drm_agp_chipset_flush(dev);
 out:
         obj_priv->phys_obj->cur_obj = NULL;
@@ -3693,7 +3695,7 @@ i915_gem_attach_phys_object(struct drm_device *dev,
         obj_priv->phys_obj = dev_priv->mm.phys_objs[id - 1];
         obj_priv->phys_obj->cur_obj = obj;
 
-        ret = i915_gem_object_get_page_list(obj);
+        ret = i915_gem_object_get_pages(obj);
         if (ret) {
                 DRM_ERROR("failed to get page list\n");
                 goto out;
@@ -3702,7 +3704,7 @@ i915_gem_attach_phys_object(struct drm_device *dev,
         page_count = obj->size / PAGE_SIZE;
 
         for (i = 0; i < page_count; i++) {
-                char *src = kmap_atomic(obj_priv->page_list[i], KM_USER0);
+                char *src = kmap_atomic(obj_priv->pages[i], KM_USER0);
                 char *dst = obj_priv->phys_obj->handle->vaddr + (i * PAGE_SIZE);
 
                 memcpy(dst, src, PAGE_SIZE);