drm/radeon: add an exclusive lock for GPU reset v2

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>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/drivers/gpu/drm/radeon/radeon_gem.c b/drivers/gpu/drm/radeon/radeon_gem.c
index d9b0809be4e4..b0be9c4f4c91 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;
 }