linux-kernel - [PATCH 1/3] drm/dp_mst: Remove lock check in drm_atomic_get_mst_topology

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Date:   Wed, 16 Jan 2019 15:37:57 -0500
From:   Lyude Paul <lyude@...hat.com>
To:     dri-devel@...ts.freedesktop.org
Cc:     Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <maxime.ripard@...tlin.com>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, linux-kernel@...r.kernel.org
Subject: [PATCH 1/3] drm/dp_mst: Remove lock check in drm_atomic_get_mst_topology_state()

Since modesetting locks by default were added to private objects in:

commit b962a12050a3 ("drm/atomic: integrate modeset lock with private
objects")

This means that the atomic state of a drm_dp_mst_topology_mgr is now
protected by drm_dp_mst_topology_mgr->base.lock as opposed to the main
connection_status mutex. This also means that locking isn't left up to
the caller anymore, and is handled automatically in
drm_atomic_get_private_obj_state().

So, remove the WARN_ON() in drm_atomic_get_mst_topology_state() since
that's now incorrect, and update the kernel docs for the function.
Additionally since all function is now is a simple wrapper around
drm_atomic_get_private_obj_state(), it seems more reasonable to move
this out of drm_dp_mst_topology.c and turn it into an inline function in
drm_dp_mst_helper.h

Signed-off-by: Lyude Paul <lyude@...hat.com>
---
 drivers/gpu/drm/drm_dp_mst_topology.c | 25 -------------------------
 include/drm/drm_dp_mst_helper.h       | 20 ++++++++++++++++++--
 2 files changed, 18 insertions(+), 27 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 196ebba8af5f..49575b80caeb 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -3718,31 +3718,6 @@ const struct drm_private_state_funcs drm_dp_mst_topology_state_funcs = {
 };
 EXPORT_SYMBOL(drm_dp_mst_topology_state_funcs);
 
-/**
- * drm_atomic_get_mst_topology_state: get MST topology state
- *
- * @state: global atomic state
- * @mgr: MST topology manager, also the private object in this case
- *
- * This function wraps drm_atomic_get_priv_obj_state() passing in the MST atomic
- * state vtable so that the private object state returned is that of a MST
- * topology object. Also, drm_atomic_get_private_obj_state() expects the caller
- * to care of the locking, so warn if don't hold the connection_mutex.
- *
- * RETURNS:
- *
- * The MST topology state or error pointer.
- */
-struct drm_dp_mst_topology_state *drm_atomic_get_mst_topology_state(struct drm_atomic_state *state,
-								    struct drm_dp_mst_topology_mgr *mgr)
-{
-	struct drm_device *dev = mgr->dev;
-
-	WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));
-	return to_dp_mst_topology_state(drm_atomic_get_private_obj_state(state, &mgr->base));
-}
-EXPORT_SYMBOL(drm_atomic_get_mst_topology_state);
-
 /**
  * drm_dp_mst_topology_mgr_init - initialise a topology manager
  * @mgr: manager struct to initialise
diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h
index 8c97a5f92c47..263d82178ecd 100644
--- a/include/drm/drm_dp_mst_helper.h
+++ b/include/drm/drm_dp_mst_helper.h
@@ -643,8 +643,6 @@ void drm_dp_mst_dump_topology(struct seq_file *m,
 void drm_dp_mst_topology_mgr_suspend(struct drm_dp_mst_topology_mgr *mgr);
 int __must_check
 drm_dp_mst_topology_mgr_resume(struct drm_dp_mst_topology_mgr *mgr);
-struct drm_dp_mst_topology_state *drm_atomic_get_mst_topology_state(struct drm_atomic_state *state,
-								    struct drm_dp_mst_topology_mgr *mgr);
 int __must_check
 drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
 			      struct drm_dp_mst_topology_mgr *mgr,
@@ -756,4 +754,22 @@ __drm_dp_mst_state_iter_get(struct drm_atomic_state *state,
 	for ((__i) = 0; (__i) < (__state)->num_private_objs; (__i)++) \
 		for_each_if(__drm_dp_mst_state_iter_get((__state), &(mgr), NULL, &(new_state), (__i)))
 
+/**
+ * drm_atomic_get_mst_topology_state() - get MST topology state
+ * @state: global atomic state
+ * @mgr: MST topology manager, also the private object in this case
+ *
+ * This function retrieves the atomic topology state for @mgr using
+ * drm_atomic_get_priv_obj_state().
+ *
+ * Returns:
+ * The atomic MST topology state or an error pointer.
+ */
+static inline struct drm_dp_mst_topology_state *
+drm_atomic_get_mst_topology_state(struct drm_atomic_state *state,
+				  struct drm_dp_mst_topology_mgr *mgr)
+{
+	return to_dp_mst_topology_state(drm_atomic_get_private_obj_state(
+		state, &mgr->base));
+}
 #endif
-- 
2.20.1