[PATCH 6/6] drm/omap: protect omap_crtc's event with event_lock spinlock

[Archit Taneja]

The vblank_cb callback and the page_flip ioctl can occur together in different
CPU contexts. vblank_cb uses takes tje drm device's event_lock spinlock when
sending the vblank event and updating omap_crtc->event and omap_crtc->od_fb.

Use the same spinlock in page_flip, to make sure the above omap_crtc parameters
are configured sequentially.

Signed-off-by: Archit Taneja <archit at ti.com>
---
 drivers/gpu/drm/omapdrm/omap_crtc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/omapdrm/omap_crtc.c b/drivers/gpu/drm/omapdrm/omap_crtc.c
index d74c72c..9c7af42 100644
--- a/drivers/gpu/drm/omapdrm/omap_crtc.c
+++ b/drivers/gpu/drm/omapdrm/omap_crtc.c
@@ -350,6 +350,7 @@ static int omap_crtc_page_flip_locked(struct drm_crtc *crtc,
 	struct drm_device *dev = crtc->dev;
 	struct omap_crtc *omap_crtc = to_omap_crtc(crtc);
 	struct drm_gem_object *bo;
+	unsigned long flags;
 
 	DBG("%d -> %d (event=%p)", crtc->fb ? crtc->fb->base.id : -1,
 			fb->base.id, event);
@@ -359,9 +360,12 @@ static int omap_crtc_page_flip_locked(struct drm_crtc *crtc,
 		return -EINVAL;
 	}
 
+	spin_lock_irqsave(&dev->event_lock, flags);
+
 	omap_crtc->event = event;
 	omap_crtc->old_fb = crtc->fb = fb;
 
+	spin_unlock_irqrestore(&dev->event_lock, flags);
 	/*
 	 * Hold a reference temporarily until the crtc is updated
 	 * and takes the reference to the bo.  This avoids it
-- 
1.8.3.2