[PATCH v2 5/5] drm/tilcdc: WARN if CRTC is touched without CRTC lock

[Jyri Sarha]

WARN if CRTC is touched without CRTC lock. The crtc functions should
not be called simultaneously from multiple threads. Having the DRM
CRTC lock should take care of that.

tilcdc_crtc_destroy() has to take the CRTC lock befor calling
tilcdc_crtc_disable() because drm_mode_config_cleanup() does not take
the lock. If this ever changes the CRTC locking has to be removed from
tilcdc_crtc_destroy().

Signed-off-by: Jyri Sarha <jsarha at ti.com>
---
 drivers/gpu/drm/tilcdc/tilcdc_crtc.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
index 6974624..94a78e2 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
@@ -154,6 +154,8 @@ static void tilcdc_crtc_enable(struct drm_crtc *crtc)
 	struct drm_device *dev = crtc->dev;
 	struct tilcdc_crtc *tilcdc_crtc = to_tilcdc_crtc(crtc);
 
+	WARN_ON(!drm_modeset_is_locked(&crtc->mutex));
+
 	if (tilcdc_crtc->enabled)
 		return;
 
@@ -178,6 +180,8 @@ void tilcdc_crtc_disable(struct drm_crtc *crtc)
 	struct drm_device *dev = crtc->dev;
 	struct tilcdc_drm_private *priv = dev->dev_private;
 
+	WARN_ON(!drm_modeset_is_locked(&crtc->mutex));
+
 	if (!tilcdc_crtc->enabled)
 		return;
 
@@ -250,7 +254,9 @@ static void tilcdc_crtc_destroy(struct drm_crtc *crtc)
 	struct tilcdc_crtc *tilcdc_crtc = to_tilcdc_crtc(crtc);
 	struct tilcdc_drm_private *priv = crtc->dev->dev_private;
 
+	drm_modeset_lock_crtc(crtc, NULL);
 	tilcdc_crtc_disable(crtc);
+	drm_modeset_unlock_crtc(crtc);
 
 	flush_workqueue(priv->wq);
 
@@ -267,6 +273,8 @@ int tilcdc_crtc_update_fb(struct drm_crtc *crtc,
 	struct drm_device *dev = crtc->dev;
 	unsigned long flags;
 
+	WARN_ON(!drm_modeset_is_locked(&crtc->mutex));
+
 	if (tilcdc_crtc->event) {
 		dev_err(dev->dev, "already pending page flip!\n");
 		return -EBUSY;
@@ -371,6 +379,8 @@ static void tilcdc_crtc_mode_set_nofb(struct drm_crtc *crtc)
 	struct drm_display_mode *mode = &crtc->state->adjusted_mode;
 	struct drm_framebuffer *fb = crtc->primary->state->fb;
 
+	WARN_ON(!drm_modeset_is_locked(&crtc->mutex));
+
 	if (WARN_ON(!info))
 		return;
 
-- 
1.9.1