drm: create drm_framebuffer_lookup

And replace all fb lookups with it. Also add a WARN to
drm_mode_object_find since that is now no longer the blessed interface
to look up an fb. And add kerneldoc to both functions.

This only updates all callsites, but immediately drops the acquired
refence again. Hence all callers still rely on the fact that a mode fb
can't disappear while they're holding the struct mutex. Subsequent
patches will instate proper use of refcounts, and then rework the rmfb
and unref code to no longer serialize fb destruction with the
mode_config lock. We don't want that since otherwise a compositor
might end up stalling for a few frames in rmfb.

v2: Don't use kref_get_unless_zero - Greg KH doesn't like that kind of
interface.

Reviewed-by: Rob Clark <rob@ti.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 12 insertions, 12 deletions

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_ioctl.c b/drivers/gpu/drm/vmwgfx/vmwgfx_ioctl.c
index 0d6a161b204b..1b8f428accae 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_ioctl.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_ioctl.c
@@ -131,7 +131,7 @@ int vmw_present_ioctl(struct drm_device *dev, void *data,
         struct vmw_master *vmaster = vmw_master(file_priv->master);
         struct drm_vmw_rect __user *clips_ptr;
         struct drm_vmw_rect *clips = NULL;
-        struct drm_mode_object *obj;
+        struct drm_framebuffer *fb;
         struct vmw_framebuffer *vfb;
         struct vmw_resource *res;
         uint32_t num_clips;
@@ -165,15 +165,15 @@ int vmw_present_ioctl(struct drm_device *dev, void *data,
 
         drm_modeset_lock_all(dev);
 
-        mutex_lock(&dev->mode_config.fb_lock);
-        obj = drm_mode_object_find(dev, arg->fb_id, DRM_MODE_OBJECT_FB);
-        mutex_unlock(&dev->mode_config.fb_lock);
-        if (!obj) {
+        fb = drm_framebuffer_lookup(dev, arg->fb_id);
+        if (!fb) {
                 DRM_ERROR("Invalid framebuffer id.\n");
                 ret = -EINVAL;
                 goto out_no_fb;
         }
-        vfb = vmw_framebuffer_to_vfb(obj_to_fb(obj));
+        /* fb is protect by the mode_config lock, so drop the ref immediately */
+        drm_framebuffer_unreference(fb);
+        vfb = vmw_framebuffer_to_vfb(fb);
 
         ret = ttm_read_lock(&vmaster->lock, true);
         if (unlikely(ret != 0))
@@ -217,7 +217,7 @@ int vmw_present_readback_ioctl(struct drm_device *dev, void *data,
         struct vmw_master *vmaster = vmw_master(file_priv->master);
         struct drm_vmw_rect __user *clips_ptr;
         struct drm_vmw_rect *clips = NULL;
-        struct drm_mode_object *obj;
+        struct drm_framebuffer *fb;
         struct vmw_framebuffer *vfb;
         uint32_t num_clips;
         int ret;
@@ -250,16 +250,16 @@ int vmw_present_readback_ioctl(struct drm_device *dev, void *data,
 
         drm_modeset_lock_all(dev);
 
-        mutex_lock(&dev->mode_config.fb_lock);
-        obj = drm_mode_object_find(dev, arg->fb_id, DRM_MODE_OBJECT_FB);
-        mutex_unlock(&dev->mode_config.fb_lock);
-        if (!obj) {
+        fb = drm_framebuffer_lookup(dev, arg->fb_id);
+        if (!fb) {
                 DRM_ERROR("Invalid framebuffer id.\n");
                 ret = -EINVAL;
                 goto out_no_fb;
         }
+        /* fb is protect by the mode_config lock, so drop the ref immediately */
+        drm_framebuffer_unreference(fb);
 
-        vfb = vmw_framebuffer_to_vfb(obj_to_fb(obj));
+        vfb = vmw_framebuffer_to_vfb(fb);
         if (!vfb->dmabuf) {
                 DRM_ERROR("Framebuffer not dmabuf backed.\n");
                 ret = -EINVAL;