[2/2] drm/tegra: Acquire a reference to the IOVA cache

Commit Message

Dmitry Osipenko May 17, 2018, 10:53 a.m. UTC

On 23.04.2018 09:57, Thierry Reding wrote:
> From: Thierry Reding <[e-mail]>
> 
> The IOVA API uses a memory cache to allocate IOVA nodes from. To make
> sure that this cache is available, obtain a reference to it and release
> the reference when the cache is no longer needed.
> 
> On 64-bit ARM this is hidden by the fact that the DMA mapping API gets
> that reference and never releases it. On 32-bit ARM, however, the DMA
> mapping API doesn't do that, so allocation of IOVA nodes fails.
> 
> Signed-off-by: Thierry Reding <[e-mail]>
> ---
>  drivers/gpu/drm/tegra/drm.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
> index 4a696fa274a3..0540b0741df6 100644
> --- a/drivers/gpu/drm/tegra/drm.c
> +++ b/drivers/gpu/drm/tegra/drm.c
> @@ -115,6 +115,10 @@ static int tegra_drm_load(struct drm_device *drm, unsigned long flags)
>  			goto free;
>  		}
>  
> +		err = iova_cache_get();
> +		if (err < 0)
> +			goto domain;
> +
>  		geometry = &tegra->domain->geometry;
>  		gem_start = geometry->aperture_start;
>  		gem_end = geometry->aperture_end - CARVEOUT_SZ;
> @@ -205,11 +209,12 @@ static int tegra_drm_load(struct drm_device *drm, unsigned long flags)
>  	tegra_drm_fb_free(drm);
>  config:
>  	drm_mode_config_cleanup(drm);
> -
> +domain:
>  	if (tegra->domain) {
>  		mutex_destroy(&tegra->mm_lock);
>  		drm_mm_takedown(&tegra->mm);
>  		put_iova_domain(&tegra->carveout.domain);
> +		iova_cache_put();

I've spotted that this ^ is incorrect. This will put the iova_cache without
getting it if iova_cache_get() failed.

>  		iommu_domain_free(tegra->domain);
>  	}
>  free:
> @@ -236,6 +241,7 @@ static void tegra_drm_unload(struct drm_device *drm)
>  		mutex_destroy(&tegra->mm_lock);
>  		drm_mm_takedown(&tegra->mm);
>  		put_iova_domain(&tegra->carveout.domain);
> +		iova_cache_put();
>  		iommu_domain_free(tegra->domain);
>  	}
>  
> 

Thierry, please update the patch:

 		gem_end = geometry->aperture_end - CARVEOUT_SZ;
@@ -194,8 +198,11 @@ static int tegra_drm_load(struct drm_device *drm, unsigned
long flags)
 		mutex_destroy(&tegra->mm_lock);
 		drm_mm_takedown(&tegra->mm);
 		put_iova_domain(&tegra->carveout.domain);
-		iommu_domain_free(tegra->domain);
+		iova_cache_put();
 	}
+domain:
+	if (tegra->domain)
+		iommu_domain_free(tegra->domain);
 free:
 	kfree(tegra);
 	return err;
@@ -220,6 +227,7 @@ static void tegra_drm_unload(struct drm_device *drm)
 		mutex_destroy(&tegra->mm_lock);
 		drm_mm_takedown(&tegra->mm);
 		put_iova_domain(&tegra->carveout.domain);
+		iova_cache_put();
 		iommu_domain_free(tegra->domain);
 	}

Patch

diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
index 4a59ac4d7793..26ce98479fb6 100644
--- a/drivers/gpu/drm/tegra/drm.c
+++ b/drivers/gpu/drm/tegra/drm.c
@@ -98,6 +98,10 @@  static int tegra_drm_load(struct drm_device *drm, unsigned
long flags)
 			goto free;
 		}

+		err = iova_cache_get();
+		if (err < 0)
+			goto domain;
+
 		geometry = &tegra->domain->geometry;
 		gem_start = geometry->aperture_start;