[Intel-gfx] [PATCH] drm/i915: don't update the dri1 breadcrumb with modesetting

[Daniel Vetter]

The update is horribly racy since it doesn't protect at all against
concurrent closing of the master fd. And it can't really since that
requires us to grab a mutex.

Instead of jumping through hoops and offloading this to a worker
thread just block this bit of code for the modesetting driver.

Reported-by: Eugene Shatokhin <eugene.shatokhin at rosalab.ru>
Cc: Eugene Shatokhin <eugene.shatokhin at rosalab.ru>
Cc: stable at vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
---
 drivers/gpu/drm/i915/i915_dma.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 197db0993a24..0a42e2f7bcf8 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -83,6 +83,9 @@ void i915_update_dri1_breadcrumb(struct drm_device *dev)
 	drm_i915_private_t *dev_priv = dev->dev_private;
 	struct drm_i915_master_private *master_priv;
 
+	if (drm_core_check_feature(dev, DRIVER_MODESET))
+		return;
+
 	if (dev->primary->master) {
 		master_priv = dev->primary->master->driver_priv;
 		if (master_priv->sarea_priv)
-- 
1.8.4.3