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

Christian König <deathsimple@xxxxxxxxxxx> · Fri, 06 Jul 2012 10:44:15 +0200

On 02.07.2012 18:45, j.glisse@xxxxxxxxx wrote:
From: Jerome Glisse <jglisse@xxxxxxxxxx>

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@xxxxxxxxxx>
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@xxxxxxx>

---
  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;
  }


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