Re: [PATCH] drm/radeon: add an exclusive lock for GPU reset v2

["Christian König" <deathsimple@vodafone.de>]

On 02.07.2012 18:45, j.glisse@gmail.com wrote:
> From: Jerome Glisse <jglisse@redhat.com>
>
> GPU reset need to be exclusive, one happening at a time. For this
> add a rw semaphore so that any path that trigger GPU activities
> have to take the semaphore as a reader thus allowing concurency.
>
> The GPU reset path take the semaphore as a writer ensuring that
> no concurrent reset take place.
>
> v2: init rw semaphore
>
> Signed-off-by: Jerome Glisse <jglisse@redhat.com>
Maybe we don't want to call it "exclusive_lock", cause a lock is always 
somehow exclusive. Anyway it's:

Reviewed-by: Christian König <christian.koenig@amd.com>

> ---
>   drivers/gpu/drm/radeon/radeon.h        |    1 +
>   drivers/gpu/drm/radeon/radeon_cs.c     |    5 +++++
>   drivers/gpu/drm/radeon/radeon_device.c |    3 +++
>   drivers/gpu/drm/radeon/radeon_gem.c    |    8 ++++++++
>   4 files changed, 17 insertions(+)
>
> diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h
> index 77b4519b..29d6986 100644
> --- a/drivers/gpu/drm/radeon/radeon.h
> +++ b/drivers/gpu/drm/radeon/radeon.h
> @@ -1446,6 +1446,7 @@ struct radeon_device {
>   	struct device			*dev;
>   	struct drm_device		*ddev;
>   	struct pci_dev			*pdev;
> +	struct rw_semaphore		exclusive_lock;
>   	/* ASIC */
>   	union radeon_asic_config	config;
>   	enum radeon_family		family;
> diff --git a/drivers/gpu/drm/radeon/radeon_cs.c b/drivers/gpu/drm/radeon/radeon_cs.c
> index f1b7527..7ee6491 100644
> --- a/drivers/gpu/drm/radeon/radeon_cs.c
> +++ b/drivers/gpu/drm/radeon/radeon_cs.c
> @@ -499,7 +499,9 @@ int radeon_cs_ioctl(struct drm_device *dev, void *data, struct drm_file *filp)
>   	struct radeon_cs_parser parser;
>   	int r;
>   
> +	down_read(&rdev->exclusive_lock);
>   	if (!rdev->accel_working) {
> +		up_read(&rdev->exclusive_lock);
>   		return -EBUSY;
>   	}
>   	/* initialize parser */
> @@ -512,6 +514,7 @@ int radeon_cs_ioctl(struct drm_device *dev, void *data, struct drm_file *filp)
>   	if (r) {
>   		DRM_ERROR("Failed to initialize parser !\n");
>   		radeon_cs_parser_fini(&parser, r);
> +		up_read(&rdev->exclusive_lock);
>   		r = radeon_cs_handle_lockup(rdev, r);
>   		return r;
>   	}
> @@ -520,6 +523,7 @@ int radeon_cs_ioctl(struct drm_device *dev, void *data, struct drm_file *filp)
>   		if (r != -ERESTARTSYS)
>   			DRM_ERROR("Failed to parse relocation %d!\n", r);
>   		radeon_cs_parser_fini(&parser, r);
> +		up_read(&rdev->exclusive_lock);
>   		r = radeon_cs_handle_lockup(rdev, r);
>   		return r;
>   	}
> @@ -533,6 +537,7 @@ int radeon_cs_ioctl(struct drm_device *dev, void *data, struct drm_file *filp)
>   	}
>   out:
>   	radeon_cs_parser_fini(&parser, r);
> +	up_read(&rdev->exclusive_lock);
>   	r = radeon_cs_handle_lockup(rdev, r);
>   	return r;
>   }
> diff --git a/drivers/gpu/drm/radeon/radeon_device.c b/drivers/gpu/drm/radeon/radeon_device.c
> index f654ba8..254fdb4 100644
> --- a/drivers/gpu/drm/radeon/radeon_device.c
> +++ b/drivers/gpu/drm/radeon/radeon_device.c
> @@ -734,6 +734,7 @@ int radeon_device_init(struct radeon_device *rdev,
>   	mutex_init(&rdev->gem.mutex);
>   	mutex_init(&rdev->pm.mutex);
>   	init_rwsem(&rdev->pm.mclk_lock);
> +	init_rwsem(&rdev->exclusive_lock);
>   	init_waitqueue_head(&rdev->irq.vblank_queue);
>   	init_waitqueue_head(&rdev->irq.idle_queue);
>   	r = radeon_gem_init(rdev);
> @@ -988,6 +989,7 @@ int radeon_gpu_reset(struct radeon_device *rdev)
>   	int r;
>   	int resched;
>   
> +	down_write(&rdev->exclusive_lock);
>   	radeon_save_bios_scratch_regs(rdev);
>   	/* block TTM */
>   	resched = ttm_bo_lock_delayed_workqueue(&rdev->mman.bdev);
> @@ -1007,6 +1009,7 @@ int radeon_gpu_reset(struct radeon_device *rdev)
>   		dev_info(rdev->dev, "GPU reset failed\n");
>   	}
>   
> +	up_write(&rdev->exclusive_lock);
>   	return r;
>   }
>   
> diff --git a/drivers/gpu/drm/radeon/radeon_gem.c b/drivers/gpu/drm/radeon/radeon_gem.c
> index d9b0809..b0be9c4 100644
> --- a/drivers/gpu/drm/radeon/radeon_gem.c
> +++ b/drivers/gpu/drm/radeon/radeon_gem.c
> @@ -215,12 +215,14 @@ int radeon_gem_create_ioctl(struct drm_device *dev, void *data,
>   	uint32_t handle;
>   	int r;
>   
> +	down_read(&rdev->exclusive_lock);
>   	/* create a gem object to contain this object in */
>   	args->size = roundup(args->size, PAGE_SIZE);
>   	r = radeon_gem_object_create(rdev, args->size, args->alignment,
>   					args->initial_domain, false,
>   					false, &gobj);
>   	if (r) {
> +		up_read(&rdev->exclusive_lock);
>   		r = radeon_gem_handle_lockup(rdev, r);
>   		return r;
>   	}
> @@ -228,10 +230,12 @@ int radeon_gem_create_ioctl(struct drm_device *dev, void *data,
>   	/* drop reference from allocate - handle holds it now */
>   	drm_gem_object_unreference_unlocked(gobj);
>   	if (r) {
> +		up_read(&rdev->exclusive_lock);
>   		r = radeon_gem_handle_lockup(rdev, r);
>   		return r;
>   	}
>   	args->handle = handle;
> +	up_read(&rdev->exclusive_lock);
>   	return 0;
>   }
>   
> @@ -240,6 +244,7 @@ int radeon_gem_set_domain_ioctl(struct drm_device *dev, void *data,
>   {
>   	/* transition the BO to a domain -
>   	 * just validate the BO into a certain domain */
> +	struct radeon_device *rdev = dev->dev_private;
>   	struct drm_radeon_gem_set_domain *args = data;
>   	struct drm_gem_object *gobj;
>   	struct radeon_bo *robj;
> @@ -247,10 +252,12 @@ int radeon_gem_set_domain_ioctl(struct drm_device *dev, void *data,
>   
>   	/* for now if someone requests domain CPU -
>   	 * just make sure the buffer is finished with */
> +	down_read(&rdev->exclusive_lock);
>   
>   	/* just do a BO wait for now */
>   	gobj = drm_gem_object_lookup(dev, filp, args->handle);
>   	if (gobj == NULL) {
> +		up_read(&rdev->exclusive_lock);
>   		return -ENOENT;
>   	}
>   	robj = gem_to_radeon_bo(gobj);
> @@ -258,6 +265,7 @@ int radeon_gem_set_domain_ioctl(struct drm_device *dev, void *data,
>   	r = radeon_gem_set_domain(gobj, args->read_domains, args->write_domain);
>   
>   	drm_gem_object_unreference_unlocked(gobj);
> +	up_read(&rdev->exclusive_lock);
>   	r = radeon_gem_handle_lockup(robj->rdev, r);
>   	return r;
>   }