On Mon, Nov 30, 2015 at 03:22:49PM -0800, Matt Roper wrote:
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@ffwll.ch> Date: Thu Jul 9 23:44:28 2015 +0200 drm: Check locking in drm_for_each_connectorCc: Daniel Vetter daniel.vetter@ffwll.ch Cc: Maarten Lankhorst maarten.lankhorst@linux.intel.com Signed-off-by: Matt Roper matthew.d.roper@intel.com
These helpers are wip and Thierry is working on some additional higher-level wrappers for bullet proof save/restore for atomic drivers. It's very much intentinoal that this function here does _not_ grab any locks - if it does the higher-level magic would be impossible. -Daniel
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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