Re: [PATCH 1/9 v3] drm/i915: Move struct_mutex to drm_i915_private

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Wed, Aug 13, 2025 at 10:50:25AM -0300, Luiz Otavio Mello wrote:
> 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>
> ---
>  drivers/gpu/drm/drm_drv.c                  |  2 --
>  drivers/gpu/drm/i915/gt/uc/intel_guc_log.c |  4 ++--
>  drivers/gpu/drm/i915/i915_driver.c         |  2 ++
>  drivers/gpu/drm/i915/i915_drv.h            | 11 +++++++++++
>  drivers/gpu/drm/i915/i915_irq.c            |  4 ++--
>  include/drm/drm_device.h                   | 10 ----------

drm, drm-misc maintainers, ack to merge this through drm-intel-next?

>  6 files changed, 17 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> index cdd591b11488..ad3aee354ba3 100644
> --- a/drivers/gpu/drm/drm_drv.c
> +++ b/drivers/gpu/drm/drm_drv.c
> @@ -694,7 +694,6 @@ 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,
> @@ -735,7 +734,6 @@ 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);
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_log.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_log.c
> index 09a64f224c49..65ffcaeee4b9 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_log.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_log.c
> @@ -677,7 +677,7 @@ 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;
> @@ -695,7 +695,7 @@ 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;
>  }
> diff --git a/drivers/gpu/drm/i915/i915_driver.c b/drivers/gpu/drm/i915/i915_driver.c
> index c6263c6d3384..d1559fd8ad3d 100644
> --- a/drivers/gpu/drm/i915/i915_driver.c
> +++ b/drivers/gpu/drm/i915/i915_driver.c
> @@ -233,6 +233,7 @@ 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);
> @@ -291,6 +292,7 @@ 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);
>  
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 4e4e89746aa6..15f66a7d496d 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -222,6 +222,17 @@ 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 */
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index 191ed8bb1d9c..cdfb09464134 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/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)
> diff --git a/include/drm/drm_device.h b/include/drm/drm_device.h
> index a33aedd5e9ec..016df5529d46 100644
> --- a/include/drm/drm_device.h
> +++ b/include/drm/drm_device.h
> @@ -188,16 +188,6 @@ 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:
>  	 *
> -- 
> 2.50.1
>