Re: [PATCH v3 1/2] drm/etnaviv: Reference count struct etnaviv_file_private

[Lucas Stach <l.stach@pengutronix.de>]

Am Freitag, dem 10.07.2026 um 14:03 +0200 schrieb Christian Gmeiner:
> From: Christian Gmeiner <cgmeiner@igalia.com>
> 
> The next commit updates per-context data from the GPU reset path, which
> runs in the scheduler timeout worker. This can race with closing the DRM
> file: drm_sched_entity_flush() only waits until the entity queue is
> empty, it does not wait for jobs still running on the hardware. So the
> context can already be freed while the reset path still needs it.
> 
> Reference count the context and let every submit hold a reference, the
> same way a submit already keeps its mmu context and pid alive. No
> functional change.
> 
> Signed-off-by: Christian Gmeiner <cgmeiner@igalia.com>

Reviewed-by: Lucas Stach <l.stach@pengutronix.de>

> ---
>  drivers/gpu/drm/etnaviv/etnaviv_drv.c        | 17 ++++++++++++++++-
>  drivers/gpu/drm/etnaviv/etnaviv_drv.h        | 11 +++++++++++
>  drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c |  5 ++++-
>  3 files changed, 31 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_drv.c b/drivers/gpu/drm/etnaviv/etnaviv_drv.c
> index 08aca9035fc1..a27ed014fb4e 100644
> --- a/drivers/gpu/drm/etnaviv/etnaviv_drv.c
> +++ b/drivers/gpu/drm/etnaviv/etnaviv_drv.c
> @@ -60,6 +60,19 @@ static void load_gpu(struct drm_device *dev)
>  	}
>  }
>  
> +static void etnaviv_file_private_release(struct kref *kref)
> +{
> +	struct etnaviv_file_private *ctx =
> +		container_of(kref, struct etnaviv_file_private, refcount);
> +
> +	kfree(ctx);
> +}
> +
> +void etnaviv_file_private_put(struct etnaviv_file_private *ctx)
> +{
> +	kref_put(&ctx->refcount, etnaviv_file_private_release);
> +}
> +
>  static int etnaviv_open(struct drm_device *dev, struct drm_file *file)
>  {
>  	struct etnaviv_drm_private *priv = dev->dev_private;
> @@ -70,6 +83,8 @@ static int etnaviv_open(struct drm_device *dev, struct drm_file *file)
>  	if (!ctx)
>  		return -ENOMEM;
>  
> +	kref_init(&ctx->refcount);
> +
>  	ret = xa_alloc_cyclic(&priv->active_contexts, &ctx->id, ctx,
>  			      xa_limit_32b, &priv->next_context_id, GFP_KERNEL);
>  	if (ret < 0)
> @@ -120,7 +135,7 @@ static void etnaviv_postclose(struct drm_device *dev, struct drm_file *file)
>  
>  	xa_erase(&priv->active_contexts, ctx->id);
>  
> -	kfree(ctx);
> +	etnaviv_file_private_put(ctx);
>  }
>  
>  /*
> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_drv.h b/drivers/gpu/drm/etnaviv/etnaviv_drv.h
> index 55a9e745604d..cba4323ae589 100644
> --- a/drivers/gpu/drm/etnaviv/etnaviv_drv.h
> +++ b/drivers/gpu/drm/etnaviv/etnaviv_drv.h
> @@ -7,6 +7,7 @@
>  #define __ETNAVIV_DRV_H__
>  
>  #include <linux/io.h>
> +#include <linux/kref.h>
>  #include <linux/list.h>
>  #include <linux/mm_types.h>
>  #include <linux/sizes.h>
> @@ -29,6 +30,7 @@ struct etnaviv_iommu_global;
>  #define ETNAVIV_SOFTPIN_START_ADDRESS	SZ_4M /* must be >= SUBALLOC_SIZE */
>  
>  struct etnaviv_file_private {
> +	struct kref refcount;
>  	int id;
>  	struct etnaviv_iommu_context	*mmu;
>  	struct drm_sched_entity		sched_entity[ETNA_MAX_PIPES];
> @@ -53,6 +55,15 @@ struct etnaviv_drm_private {
>  	struct etnaviv_cmdbuf *flop_reset_data_ppu;
>  };
>  
> +void etnaviv_file_private_put(struct etnaviv_file_private *ctx);
> +
> +static inline struct etnaviv_file_private *
> +etnaviv_file_private_get(struct etnaviv_file_private *ctx)
> +{
> +	kref_get(&ctx->refcount);
> +	return ctx;
> +}
> +
>  int etnaviv_ioctl_gem_submit(struct drm_device *dev, void *data,
>  		struct drm_file *file);
>  
> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c b/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c
> index 1a77a09b3377..98f1f59a8b05 100644
> --- a/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c
> +++ b/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c
> @@ -398,6 +398,9 @@ static void submit_cleanup(struct kref *kref)
>  
>  	put_pid(submit->pid);
>  
> +	if (submit->ctx)
> +		etnaviv_file_private_put(submit->ctx);
> +
>  	kfree(submit->pmrs);
>  	kfree(submit);
>  }
> @@ -526,7 +529,7 @@ int etnaviv_ioctl_gem_submit(struct drm_device *dev, void *data,
>  	if (ret)
>  		goto err_submit_put;
>  
> -	submit->ctx = file->driver_priv;
> +	submit->ctx = etnaviv_file_private_get(file->driver_priv);
>  	submit->mmu_context = etnaviv_iommu_context_get(submit->ctx->mmu);
>  	submit->exec_state = args->exec_state;
>  	submit->flags = args->flags;