drm/exynos: release unhandled page flip events at postclose.

This patch resolves a dead lock issue that could be incurred when
exynos_drm_crtc_dpms function was called.

The exynos_drm_crtc_dpms function waits for the completion of pended
page flip events. However, preclose callback - this releases all unhandled
page flip events - is called prior to the exynos_drm_crtc_dpms function call
when drm is closed. So at this time, this will make the exynos_drm_crtc_dpms
to wait infiniately for the completion of the page flip events.

This patch releases the unhandled page flip events at postclose instead
of preclose so that exynos_drm_crtc_dpms function can be waked up.

Changelog v2:
- fix a memory leak when drm is closed.
  . it has a memory leak when a requeste page flip is handled after
    drm_events_release() is called and before drm_fb_release()
    is called. At this time, a drm_pending_event will not be freed.
    So also this chage releases the drm_pending_event at postclose().
    And it calls drm_vblank_put() for pair if there is any unhandled page
    flip event.

Signed-off-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>

1 files changed, 22 insertions, 13 deletions

diff --git a/drivers/gpu/drm/exynos/exynos_drm_drv.c b/drivers/gpu/drm/exynos/exynos_drm_drv.c
index b676006a95a0..22b8f5eced80 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_drv.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_drv.c
@@ -173,28 +173,37 @@ static int exynos_drm_open(struct drm_device *dev, struct drm_file *file)
 static void exynos_drm_preclose(struct drm_device *dev,
                                         struct drm_file *file)
 {
+        exynos_drm_subdrv_close(dev, file);
+}
+
+static void exynos_drm_postclose(struct drm_device *dev, struct drm_file *file)
+{
         struct exynos_drm_private *private = dev->dev_private;
-        struct drm_pending_vblank_event *e, *t;
+        struct drm_pending_vblank_event *v, *vt;
+        struct drm_pending_event *e, *et;
         unsigned long flags;
 
-        /* release events of current file */
+        if (!file->driver_priv)
+                return;
+
+        /* Release all events not unhandled by page flip handler. */
         spin_lock_irqsave(&dev->event_lock, flags);
-        list_for_each_entry_safe(e, t, &private->pageflip_event_list,
+        list_for_each_entry_safe(v, vt, &private->pageflip_event_list,
                         base.link) {
-                if (e->base.file_priv == file) {
-                        list_del(&e->base.link);
-                        e->base.destroy(&e->base);
+                if (v->base.file_priv == file) {
+                        list_del(&v->base.link);
+                        drm_vblank_put(dev, v->pipe);
+                        v->base.destroy(&v->base);
                 }
         }
-        spin_unlock_irqrestore(&dev->event_lock, flags);
 
-        exynos_drm_subdrv_close(dev, file);
-}
+        /* Release all events handled by page flip handler but not freed. */
+        list_for_each_entry_safe(e, et, &file->event_list, link) {
+                list_del(&e->link);
+                e->destroy(e);
+        }
+        spin_unlock_irqrestore(&dev->event_lock, flags);
 
-static void exynos_drm_postclose(struct drm_device *dev, struct drm_file *file)
-{
-        if (!file->driver_priv)
-                return;
 
         kfree(file->driver_priv);
         file->driver_priv = NULL;