From: Ville Syrjälä <ville.syrj...@linux.intel.com>

drm_client_firmware_config() is currently picking up the current
mode of the crtc via the legacy crtc->mode, which is not supposed
to be used by atomic drivers at all. We can't simply switch over
to the proper crtc->state->mode because we drop the crtc->mutex
(which protects crtc->state) before the mode gets used.

The most straightforward solution to extend the lifetime of
modes[] seem to be to make full copies of the modes.

And with this we can undo also commit 3eadd887dbac
("drm/client:Fully protect modes[] with dev->mode_config.mutex")
as the lifetime of modes[] no longer has anything to do with
that lock.

v2: Don't try to copy NULL modes
v3: Keep storing pointers and use drm_mode_{duplicate,destroy}()

Signed-off-by: Ville Syrjälä <ville.syrj...@linux.intel.com>
---
 drivers/gpu/drm/drm_client_modeset.c | 62 +++++++++++++++++++++-------
 1 file changed, 47 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/drm_client_modeset.c 
b/drivers/gpu/drm/drm_client_modeset.c
index 148257287ae4..ff034359f063 100644
--- a/drivers/gpu/drm/drm_client_modeset.c
+++ b/drivers/gpu/drm/drm_client_modeset.c
@@ -265,6 +265,25 @@ static void drm_client_connectors_enabled(struct 
drm_connector *connectors[],
                enabled[i] = drm_connector_enabled(connectors[i], false);
 }
 
+static void mode_replace(struct drm_device *dev,
+                        const struct drm_display_mode **dst,
+                        const struct drm_display_mode *src)
+{
+       drm_mode_destroy(dev, (struct drm_display_mode *)*dst);
+
+       *dst = src ? drm_mode_duplicate(dev, src) : NULL;
+}
+
+static void modes_destroy(struct drm_device *dev,
+                         const struct drm_display_mode *modes[],
+                         int count)
+{
+       int i;
+
+       for (i = 0; i < count; i++)
+               mode_replace(dev, &modes[i], NULL);
+}
+
 static bool drm_client_target_cloned(struct drm_device *dev,
                                     struct drm_connector *connectors[],
                                     unsigned int connector_count,
@@ -296,7 +315,9 @@ static bool drm_client_target_cloned(struct drm_device *dev,
        for (i = 0; i < connector_count; i++) {
                if (!enabled[i])
                        continue;
-               modes[i] = drm_connector_pick_cmdline_mode(connectors[i]);
+
+               mode_replace(dev, &modes[i],
+                            drm_connector_pick_cmdline_mode(connectors[i]));
                if (!modes[i]) {
                        can_clone = false;
                        break;
@@ -335,7 +356,7 @@ static bool drm_client_target_cloned(struct drm_device *dev,
                                           DRM_MODE_MATCH_CLOCK |
                                           DRM_MODE_MATCH_FLAGS |
                                           DRM_MODE_MATCH_3D_FLAGS))
-                               modes[i] = mode;
+                               mode_replace(dev, &modes[i], mode);
                }
                if (!modes[i])
                        can_clone = false;
@@ -445,16 +466,19 @@ static bool drm_client_target_preferred(struct drm_device 
*dev,
                }
 
                mode_type = "cmdline";
-               modes[i] = drm_connector_pick_cmdline_mode(connector);
+               mode_replace(dev, &modes[i],
+                            drm_connector_pick_cmdline_mode(connector));
 
                if (!modes[i]) {
                        mode_type = "preferred";
-                       modes[i] = drm_connector_preferred_mode(connector, 
width, height);
+                       mode_replace(dev, &modes[i],
+                                    drm_connector_preferred_mode(connector, 
width, height));
                }
 
                if (!modes[i]) {
                        mode_type = "first";
-                       modes[i] = drm_connector_first_mode(connector);
+                       mode_replace(dev, &modes[i],
+                                    drm_connector_first_mode(connector));
                }
 
                /*
@@ -472,10 +496,12 @@ static bool drm_client_target_preferred(struct drm_device 
*dev,
                             connector->tile_v_loc == 0 &&
                             !drm_connector_get_tiled_mode(connector))) {
                                mode_type = "non tiled";
-                               modes[i] = 
drm_connector_fallback_non_tiled_mode(connector);
+                               mode_replace(dev, &modes[i],
+                                            
drm_connector_fallback_non_tiled_mode(connector));
                        } else {
                                mode_type = "tiled";
-                               modes[i] = 
drm_connector_get_tiled_mode(connector);
+                               mode_replace(dev, &modes[i],
+                                            
drm_connector_get_tiled_mode(connector));
                        }
                }
 
@@ -690,16 +716,19 @@ static bool drm_client_firmware_config(struct 
drm_client_dev *client,
                }
 
                mode_type = "cmdline";
-               modes[i] = drm_connector_pick_cmdline_mode(connector);
+               mode_replace(dev, &modes[i],
+                            drm_connector_pick_cmdline_mode(connector));
 
                if (!modes[i]) {
                        mode_type = "preferred";
-                       modes[i] = drm_connector_preferred_mode(connector, 
width, height);
+                       mode_replace(dev, &modes[i],
+                                    drm_connector_preferred_mode(connector, 
width, height));
                }
 
                if (!modes[i]) {
                        mode_type = "first";
-                       modes[i] = drm_connector_first_mode(connector);
+                       mode_replace(dev, &modes[i],
+                                    drm_connector_first_mode(connector));
                }
 
                /* last resort: use current mode */
@@ -716,7 +745,8 @@ static bool drm_client_firmware_config(struct 
drm_client_dev *client,
                         * fastboot check to work correctly.
                         */
                        mode_type = "current";
-                       modes[i] = &connector->state->crtc->mode;
+                       mode_replace(dev, &modes[i],
+                                    &connector->state->crtc->mode);
                }
 
                /*
@@ -726,7 +756,8 @@ static bool drm_client_firmware_config(struct 
drm_client_dev *client,
                if (connector->has_tile &&
                    num_tiled_conns < connector->num_h_tile * 
connector->num_v_tile) {
                        mode_type = "non tiled";
-                       modes[i] = 
drm_connector_fallback_non_tiled_mode(connector);
+                       mode_replace(dev, &modes[i],
+                                    
drm_connector_fallback_non_tiled_mode(connector));
                }
                crtcs[i] = new_crtc;
 
@@ -798,7 +829,6 @@ int drm_client_modeset_probe(struct drm_client_dev *client, 
unsigned int width,
        unsigned int total_modes_count = 0;
        struct drm_client_offset *offsets;
        unsigned int connector_count = 0;
-       /* points to modes protected by mode_config.mutex */
        const struct drm_display_mode **modes;
        struct drm_crtc **crtcs;
        int i, ret = 0;
@@ -850,7 +880,7 @@ int drm_client_modeset_probe(struct drm_client_dev *client, 
unsigned int width,
 
        if (!drm_client_firmware_config(client, connectors, connector_count, 
crtcs,
                                        modes, offsets, enabled, width, 
height)) {
-               memset(modes, 0, connector_count * sizeof(*modes));
+               modes_destroy(dev, modes, connector_count);
                memset(crtcs, 0, connector_count * sizeof(*crtcs));
                memset(offsets, 0, connector_count * sizeof(*offsets));
 
@@ -867,6 +897,8 @@ int drm_client_modeset_probe(struct drm_client_dev *client, 
unsigned int width,
                                      crtcs, modes, 0, width, height);
        }
 
+       mutex_unlock(&dev->mode_config.mutex);
+
        drm_client_modeset_release(client);
 
        for (i = 0; i < connector_count; i++) {
@@ -901,11 +933,11 @@ int drm_client_modeset_probe(struct drm_client_dev 
*client, unsigned int width,
                        modeset->y = offset->y;
                }
        }
-       mutex_unlock(&dev->mode_config.mutex);
 
        mutex_unlock(&client->modeset_mutex);
 out:
        kfree(crtcs);
+       modes_destroy(dev, modes, connector_count);
        kfree(modes);
        kfree(offsets);
        kfree(enabled);
-- 
2.45.3

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