Commit d9393973 authored by Thomas Hellström's avatar Thomas Hellström
Browse files

drm/i915: Remove the vma refcount 



Now that i915_vma_parked() is taking the object lock on vma destruction,
and the only user of the vma refcount, i915_gem_object_unbind()
also takes the object lock, remove the vma refcount.

v3: Documentation update.

Signed-off-by: default avatarThomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: default avatarNiranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220304082641.308069-3-thomas.hellstrom@linux.intel.com
parent e1a7ab4f

drivers/gpu/drm/i915/i915_gem.c

+13 −4
Original line number Diff line number Diff line
@@ -151,14 +151,25 @@ int i915_gem_object_unbind(struct drm_i915_gem_object *obj, 
			break;

		}



		/*

		 * Requiring the vm destructor to take the object lock

		 * before destroying a vma would help us eliminate the

		 * i915_vm_tryget() here, AND thus also the barrier stuff

		 * at the end. That's an easy fix, but sleeping locks in

		 * a kthread should generally be avoided.

		 */

		ret = -EAGAIN;

		if (!i915_vm_tryget(vma->vm))

			break;



		/* Prevent vma being freed by i915_vma_parked as we unbind */

		vma = __i915_vma_get(vma);

		spin_unlock(&obj->vma.lock);



		/*

		 * Since i915_vma_parked() takes the object lock

		 * before vma destruction, it won't race us here,

		 * and destroy the vma from under us.

		 */



		if (vma) {

			bool vm_trylock = !!(flags & I915_GEM_OBJECT_UNBIND_VM_TRYLOCK);

			ret = -EBUSY;
@@ -180,8 +191,6 @@ int i915_gem_object_unbind(struct drm_i915_gem_object *obj, 
					ret = i915_vma_unbind(vma);

				}

			}



			__i915_vma_put(vma);

		}



		i915_vm_put(vma->vm);

drivers/gpu/drm/i915/i915_vma.c

+3 −14
Original line number Diff line number Diff line
@@ -122,7 +122,6 @@ vma_create(struct drm_i915_gem_object *obj, 
	if (vma == NULL)

		return ERR_PTR(-ENOMEM);



	kref_init(&vma->ref);

	vma->ops = &vm->vma_ops;

	vma->obj = obj;

	vma->size = obj->base.size;
@@ -1628,15 +1627,6 @@ void i915_vma_reopen(struct i915_vma *vma) 
		__i915_vma_remove_closed(vma);

}



void i915_vma_release(struct kref *ref)

{

	struct i915_vma *vma = container_of(ref, typeof(*vma), ref);



	i915_active_fini(&vma->active);

	GEM_WARN_ON(vma->resource);

	i915_vma_free(vma);

}



static void force_unbind(struct i915_vma *vma)

{

	if (!drm_mm_node_allocated(&vma->node))
@@ -1665,7 +1655,9 @@ static void release_references(struct i915_vma *vma, bool vm_ddestroy) 
	if (vm_ddestroy)

		i915_vm_resv_put(vma->vm);



	__i915_vma_put(vma);

	i915_active_fini(&vma->active);

	GEM_WARN_ON(vma->resource);

	i915_vma_free(vma);

}



/**
@@ -1693,9 +1685,6 @@ static void release_references(struct i915_vma *vma, bool vm_ddestroy) 
 * - vm->mutex

 * - obj->vma.lock

 * - gt->closed_lock

 *

 * A vma user can also temporarily keep the vma alive while holding a vma

 * reference.

 */

void i915_vma_destroy_locked(struct i915_vma *vma)

{

drivers/gpu/drm/i915/i915_vma.h

+0 −14
Original line number Diff line number Diff line
@@ -222,20 +222,6 @@ void i915_vma_unlink_ctx(struct i915_vma *vma); 
void i915_vma_close(struct i915_vma *vma);

void i915_vma_reopen(struct i915_vma *vma);



static inline struct i915_vma *__i915_vma_get(struct i915_vma *vma)

{

	if (kref_get_unless_zero(&vma->ref))

		return vma;



	return NULL;

}



void i915_vma_release(struct kref *ref);

static inline void __i915_vma_put(struct i915_vma *vma)

{

	kref_put(&vma->ref, i915_vma_release);

}



void i915_vma_destroy_locked(struct i915_vma *vma);

void i915_vma_destroy(struct i915_vma *vma);

drivers/gpu/drm/i915/i915_vma_types.h

+0 −1
Original line number Diff line number Diff line
@@ -211,7 +211,6 @@ struct i915_vma { 
	 * handles (but same file) for execbuf, i.e. the number of aliases

	 * that exist in the ctx->handle_vmas LUT for this vma.

	 */

	struct kref ref;

	atomic_t open_count;

	atomic_t flags;

	/**