[ 34/56] drm/i915: dont set unpin_work if vblank_get fails

Greg Kroah-Hartman
2013-04-02T22:50:58Z

From: Jesse Barnes <jbarnes@virtuousgeek.org>

commit 7317c75e66fce0c9f82fbe6f72f7e5256b315422 upstream.

This fixes a race where we may try to finish a page flip and decrement
the refcount even if our vblank_get failed and we ended up with a
spurious flip pending interrupt.

Fixes https://bugs.freedesktop.org/show_bug.cgi?id=34211.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/gpu/drm/i915/intel_display.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)

--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -6524,11 +6524,16 @@ static int intel_crtc_page_flip(struct d
work->old_fb_obj = intel_fb->obj;
INIT_WORK(&work->work, intel_unpin_work_fn);

+ ret = drm_vblank_get(dev, intel_crtc->pipe);
+ if (ret)
+ goto free_work;
+
/* We borrow the event spin lock for protecting unpin_work */
spin_lock_irqsave(&dev->event_lock, flags);
if (intel_crtc->unpin_work) {
spin_unlock_irqrestore(&dev->event_lock, flags);
kfree(work);
+ drm_vblank_put(dev, intel_crtc->pipe);

DRM_DEBUG_DRIVER("flip queue: crtc already busy\n");
return -EBUSY;
@@ -6547,10 +6552,6 @@ static int intel_crtc_page_flip(struct d

crtc->fb = fb;

- ret = drm_vblank_get(dev, intel_crtc->pipe);
- if (ret)
- goto cleanup_objs;
-
work->pending_flip_obj = obj;

work->enable_stall_check = true;
@@ -6572,7 +6573,6 @@ static int intel_crtc_page_flip(struct d

cleanup_pending:
atomic_sub(1 << intel_crtc->plane, &work->old_fb_obj->pending_flip);
-cleanup_objs:
drm_gem_object_unreference(&work->old_fb_obj->base);
drm_gem_object_unreference(&obj->base);
mutex_unlock(&dev->struct_mutex);
@@ -6581,6 +6581,8 @@ cleanup_objs:
intel_crtc->unpin_work = NULL;
spin_unlock_irqrestore(&dev->event_lock, flags);

+ drm_vblank_put(dev, intel_crtc->pipe);
+free_work:
kfree(work);

return ret;