drm/i915: Move struct_mutex to drm_i915_private

Move legacy BKL struct_mutex from drm_device to drm_i915_private, which
is the last remaining user.

Signed-off-by: Luiz Otavio Mello <luiz.mello@estudante.ufscar.br>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://lore.kernel.org/r/20250908131518.36625-2-luiz.mello@estudante.ufscar.br
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

Author: LuizOt31

drivers/gpu/drm/drm_drv.c

@@ -697,7 +697,6 @@ static void drm_dev_init_release(struct drm_device *dev, void *res)
 	mutex_destroy(&dev->master_mutex);
 	mutex_destroy(&dev->clientlist_mutex);
 	mutex_destroy(&dev->filelist_mutex);
-	mutex_destroy(&dev->struct_mutex);
 }
 
 static int drm_dev_init(struct drm_device *dev,
@@ -738,7 +737,6 @@ static int drm_dev_init(struct drm_device *dev,
 	INIT_LIST_HEAD(&dev->vblank_event_list);
 
 	spin_lock_init(&dev->event_lock);
-	mutex_init(&dev->struct_mutex);
 	mutex_init(&dev->filelist_mutex);
 	mutex_init(&dev->clientlist_mutex);
 	mutex_init(&dev->master_mutex);

drivers/gpu/drm/i915/gt/uc/intel_guc_log.c

@@ -678,7 +678,7 @@ int intel_guc_log_set_level(struct intel_guc_log *log, u32 level)
 	if (level < GUC_LOG_LEVEL_DISABLED || level > GUC_LOG_LEVEL_MAX)
 		return -EINVAL;
 
-	mutex_lock(&i915->drm.struct_mutex);
+	mutex_lock(&i915->struct_mutex);
 
 	if (log->level == level)
 		goto out_unlock;
@@ -696,7 +696,7 @@ int intel_guc_log_set_level(struct intel_guc_log *log, u32 level)
 	log->level = level;
 
 out_unlock:
-	mutex_unlock(&i915->drm.struct_mutex);
+	mutex_unlock(&i915->struct_mutex);
 
 	return ret;
 }

drivers/gpu/drm/i915/i915_driver.c

@@ -235,6 +235,7 @@ static int i915_driver_early_probe(struct drm_i915_private *dev_priv)
 
 	intel_sbi_init(display);
 	vlv_iosf_sb_init(dev_priv);
+	mutex_init(&dev_priv->struct_mutex);
 	mutex_init(&dev_priv->sb_lock);
 
 	i915_memcpy_init_early(dev_priv);
@@ -293,6 +294,7 @@ static void i915_driver_late_release(struct drm_i915_private *dev_priv)
 	i915_workqueues_cleanup(dev_priv);
 
 	mutex_destroy(&dev_priv->sb_lock);
+	mutex_destroy(&dev_priv->struct_mutex);
 	vlv_iosf_sb_fini(dev_priv);
 	intel_sbi_fini(display);
 

drivers/gpu/drm/i915/i915_drv.h

@@ -224,6 +224,17 @@ struct drm_i915_private {
 
 	bool irqs_enabled;
 
+	/*
+	 * Currently, struct_mutex is only used by the i915 driver as a replacement
+	 * for BKL.
+	 *
+	 * For this reason, it is no longer part of struct drm_device.
+	 */
+	struct mutex struct_mutex;
+
+	/* LPT/WPT IOSF sideband protection */
+	struct mutex sbi_lock;
+
 	/* VLV/CHV IOSF sideband */
 	struct {
 		struct mutex lock; /* protect sideband access */

drivers/gpu/drm/i915/i915_irq.c

@@ -167,7 +167,7 @@ static void ivb_parity_work(struct work_struct *work)
 	 * In order to prevent a get/put style interface, acquire struct mutex
 	 * any time we access those registers.
 	 */
-	mutex_lock(&dev_priv->drm.struct_mutex);
+	mutex_lock(&dev_priv->struct_mutex);
 
 	/* If we've screwed up tracking, just let the interrupt fire again */
 	if (drm_WARN_ON(&dev_priv->drm, !dev_priv->l3_parity.which_slice))
@@ -225,7 +225,7 @@ static void ivb_parity_work(struct work_struct *work)
 	gen5_gt_enable_irq(gt, GT_PARITY_ERROR(dev_priv));
 	spin_unlock_irq(gt->irq_lock);
 
-	mutex_unlock(&dev_priv->drm.struct_mutex);
+	mutex_unlock(&dev_priv->struct_mutex);
 }
 
 static irqreturn_t valleyview_irq_handler(int irq, void *arg)

include/drm/drm_device.h

@@ -186,16 +186,6 @@ struct drm_device {
 	/** @unique: Unique name of the device */
 	char *unique;
 
-	/**
-	 * @struct_mutex:
-	 *
-	 * Lock for others (not &drm_minor.master and &drm_file.is_master)
-	 *
-	 * TODO: This lock used to be the BKL of the DRM subsystem. Move the
-	 *       lock into i915, which is the only remaining user.
-	 */
-	struct mutex struct_mutex;
-
 	/**
 	 * @master_mutex:
 	 *