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 instead
of just storing pointers. We do have to replace the NULL checks
with something else though. Checking that mode->clock!=0
should be sufficient.

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

Signed-off-by: Ville Syrjälä <ville.syrj...@linux.intel.com>
---
 drivers/gpu/drm/drm_client_modeset.c | 96 +++++++++++++++++-----------
 1 file changed, 59 insertions(+), 37 deletions(-)

diff --git a/drivers/gpu/drm/drm_client_modeset.c 
b/drivers/gpu/drm/drm_client_modeset.c
index 888323137a6a..730ed0d4bfa9 100644
--- a/drivers/gpu/drm/drm_client_modeset.c
+++ b/drivers/gpu/drm/drm_client_modeset.c
@@ -265,10 +265,21 @@ static void drm_client_connectors_enabled(struct 
drm_connector *connectors[],
                enabled[i] = drm_connector_enabled(connectors[i], false);
 }
 
+static bool mode_valid(const struct drm_display_mode *mode)
+{
+       return mode->clock != 0;
+}
+
+static void mode_copy_if_not_null(struct drm_display_mode *dst, const struct 
drm_display_mode *src)
+{
+       if (src)
+               drm_mode_copy(dst, src);
+}
+
 static bool drm_client_target_cloned(struct drm_device *dev,
                                     struct drm_connector *connectors[],
                                     unsigned int connector_count,
-                                    const struct drm_display_mode *modes[],
+                                    struct drm_display_mode modes[],
                                     struct drm_client_offset offsets[],
                                     bool enabled[], int width, int height)
 {
@@ -296,15 +307,16 @@ 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]);
-               if (!modes[i]) {
+
+               mode_copy_if_not_null(&modes[i], 
drm_connector_pick_cmdline_mode(connectors[i]));
+               if (!mode_valid(&modes[i])) {
                        can_clone = false;
                        break;
                }
                for (j = 0; j < i; j++) {
                        if (!enabled[j])
                                continue;
-                       if (!drm_mode_match(modes[j], modes[i],
+                       if (!drm_mode_match(&modes[j], &modes[i],
                                            DRM_MODE_MATCH_TIMINGS |
                                            DRM_MODE_MATCH_CLOCK |
                                            DRM_MODE_MATCH_FLAGS |
@@ -335,9 +347,9 @@ 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_copy_if_not_null(&modes[i], mode);
                }
-               if (!modes[i])
+               if (!mode_valid(&modes[i]))
                        can_clone = false;
        }
        drm_mode_destroy(dev, dmt_mode);
@@ -354,7 +366,7 @@ static bool drm_client_target_cloned(struct drm_device *dev,
 static int drm_client_get_tile_offsets(struct drm_device *dev,
                                       struct drm_connector *connectors[],
                                       unsigned int connector_count,
-                                      const struct drm_display_mode *modes[],
+                                      const struct drm_display_mode modes[],
                                       struct drm_client_offset offsets[],
                                       int idx,
                                       int h_idx, int v_idx)
@@ -368,17 +380,17 @@ static int drm_client_get_tile_offsets(struct drm_device 
*dev,
                if (!connector->has_tile)
                        continue;
 
-               if (!modes[i] && (h_idx || v_idx)) {
+               if (!mode_valid(&modes[i]) && (h_idx || v_idx)) {
                        drm_dbg_kms(dev,
                                    "[CONNECTOR:%d:%s] no modes for connector 
tiled %d\n",
                                    connector->base.id, connector->name, i);
                        continue;
                }
                if (connector->tile_h_loc < h_idx)
-                       hoffset += modes[i]->hdisplay;
+                       hoffset += modes[i].hdisplay;
 
                if (connector->tile_v_loc < v_idx)
-                       voffset += modes[i]->vdisplay;
+                       voffset += modes[i].vdisplay;
        }
        offsets[idx].x = hoffset;
        offsets[idx].y = voffset;
@@ -389,7 +401,7 @@ static int drm_client_get_tile_offsets(struct drm_device 
*dev,
 static bool drm_client_target_preferred(struct drm_device *dev,
                                        struct drm_connector *connectors[],
                                        unsigned int connector_count,
-                                       const struct drm_display_mode *modes[],
+                                       struct drm_display_mode modes[],
                                        struct drm_client_offset offsets[],
                                        bool enabled[], int width, int height)
 {
@@ -445,16 +457,19 @@ static bool drm_client_target_preferred(struct drm_device 
*dev,
                }
 
                mode_type = "cmdline";
-               modes[i] = drm_connector_pick_cmdline_mode(connector);
+               mode_copy_if_not_null(&modes[i],
+                                     
drm_connector_pick_cmdline_mode(connector));
 
-               if (!modes[i]) {
+               if (!mode_valid(&modes[i])) {
                        mode_type = "preferred";
-                       modes[i] = drm_connector_preferred_mode(connector, 
width, height);
+                       mode_copy_if_not_null(&modes[i],
+                                             
drm_connector_preferred_mode(connector, width, height));
                }
 
-               if (!modes[i]) {
+               if (!mode_valid(&modes[i])) {
                        mode_type = "first";
-                       modes[i] = drm_connector_first_mode(connector);
+                       mode_copy_if_not_null(&modes[i],
+                                             
drm_connector_first_mode(connector));
                }
 
                /*
@@ -472,17 +487,19 @@ 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_copy_if_not_null(&modes[i],
+                                                     
drm_connector_fallback_non_tiled_mode(connector));
                        } else {
                                mode_type = "tiled";
-                               modes[i] = 
drm_connector_get_tiled_mode(connector);
+                               mode_copy_if_not_null(&modes[i],
+                                                     
drm_connector_get_tiled_mode(connector));
                        }
                }
 
-               if (modes[i])
+               if (mode_valid(&modes[i]))
                        drm_dbg_kms(dev, "[CONNECTOR:%d:%s] found %s mode: 
%s\n",
                                    connector->base.id, connector->name,
-                                   mode_type, modes[i]->name);
+                                   mode_type, modes[i].name);
                else
                        drm_dbg_kms(dev, "[CONNECTOR:%d:%s] no mode found\n",
                                    connector->base.id, connector->name);
@@ -514,7 +531,7 @@ static int drm_client_pick_crtcs(struct drm_client_dev 
*client,
                                 struct drm_connector *connectors[],
                                 unsigned int connector_count,
                                 struct drm_crtc *best_crtcs[],
-                                const struct drm_display_mode *modes[],
+                                const struct drm_display_mode modes[],
                                 int n, int width, int height)
 {
        struct drm_device *dev = client->dev;
@@ -532,7 +549,7 @@ static int drm_client_pick_crtcs(struct drm_client_dev 
*client,
        best_crtcs[n] = NULL;
        best_score = drm_client_pick_crtcs(client, connectors, connector_count,
                                           best_crtcs, modes, n + 1, width, 
height);
-       if (modes[n] == NULL)
+       if (!mode_valid(&modes[n]))
                return best_score;
 
        crtcs = kcalloc(connector_count, sizeof(*crtcs), GFP_KERNEL);
@@ -566,7 +583,7 @@ static int drm_client_pick_crtcs(struct drm_client_dev 
*client,
                        if (dev->mode_config.num_crtc > 1)
                                continue;
 
-                       if (!drm_mode_equal(modes[o], modes[n]))
+                       if (!drm_mode_equal(&modes[o], &modes[n]))
                                continue;
                }
 
@@ -589,7 +606,7 @@ static bool drm_client_firmware_config(struct 
drm_client_dev *client,
                                       struct drm_connector *connectors[],
                                       unsigned int connector_count,
                                       struct drm_crtc *crtcs[],
-                                      const struct drm_display_mode *modes[],
+                                      struct drm_display_mode modes[],
                                       struct drm_client_offset offsets[],
                                       bool enabled[], int width, int height)
 {
@@ -690,20 +707,23 @@ static bool drm_client_firmware_config(struct 
drm_client_dev *client,
                }
 
                mode_type = "cmdline";
-               modes[i] = drm_connector_pick_cmdline_mode(connector);
+               mode_copy_if_not_null(&modes[i],
+                                     
drm_connector_pick_cmdline_mode(connector));
 
-               if (!modes[i]) {
+               if (!mode_valid(&modes[i])) {
                        mode_type = "preferred";
-                       modes[i] = drm_connector_preferred_mode(connector, 
width, height);
+                       mode_copy_if_not_null(&modes[i],
+                                             
drm_connector_preferred_mode(connector, width, height));
                }
 
-               if (!modes[i]) {
+               if (!mode_valid(&modes[i])) {
                        mode_type = "first";
-                       modes[i] = drm_connector_first_mode(connector);
+                       mode_copy_if_not_null(&modes[i],
+                                             
drm_connector_first_mode(connector));
                }
 
                /* last resort: use current mode */
-               if (!modes[i]) {
+               if (!mode_valid(&modes[i])) {
                        /*
                         * IMPORTANT: We want to use the adjusted mode (i.e.
                         * after the panel fitter upscaling) as the initial
@@ -716,7 +736,8 @@ 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_copy_if_not_null(&modes[i],
+                                             &connector->state->crtc->mode);
                }
 
                /*
@@ -726,14 +747,15 @@ 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_copy_if_not_null(&modes[i],
+                                             
drm_connector_fallback_non_tiled_mode(connector));
                }
                crtcs[i] = new_crtc;
 
                drm_dbg_kms(dev, "[CONNECTOR::%d:%s] on [CRTC:%d:%s] using %s 
mode: %s\n",
                            connector->base.id, connector->name,
                            new_crtc->base.id, new_crtc->name,
-                           mode_type, modes[i]->name);
+                           mode_type, modes[i].name);
 
                fallback = false;
                conn_configured |= BIT(i);
@@ -789,8 +811,7 @@ 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_display_mode *modes;
        struct drm_crtc **crtcs;
        int i, ret = 0;
        bool *enabled;
@@ -858,10 +879,12 @@ 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++) {
-               const struct drm_display_mode *mode = modes[i];
+               const struct drm_display_mode *mode = &modes[i];
                struct drm_crtc *crtc = crtcs[i];
                struct drm_client_offset *offset = &offsets[i];
 
@@ -892,7 +915,6 @@ 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:
-- 
2.45.2

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