Callers of drm_atomic_helper_duplicate_state() may not have grabbed
locks before calling this function. We're not supposed to iterate over
connectors without holding connection_mutex (since MST allows new
connectors to be spawned at hotplug), so make sure we grab that
ourselves before invoking drm_for_each_connector(). Failure to grab
this lock would cause us to stumble over the assertion added in commit:
commit 7a3f3d6667f5f9ffd1517f6b21d64bbf5312042c
Author: Daniel Vetter <daniel.vetter@xxxxxxxx>
Date: Thu Jul 9 23:44:28 2015 +0200
drm: Check locking in drm_for_each_connector
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Signed-off-by: Matt Roper <matthew.d.roper@xxxxxxxxx>
---
drivers/gpu/drm/drm_atomic_helper.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 3731a26..e5d0b21 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -2478,6 +2478,10 @@ drm_atomic_helper_duplicate_state(struct drm_device *dev,
}
}
+ err = drm_modeset_lock(&dev->mode_config.connection_mutex, ctx);
+ if (err)
+ goto free;
+
drm_for_each_connector(conn, dev) {
struct drm_connector_state *conn_state;
--
2.1.4
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