Commit c017cf6b authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915: Drop the deferred active reference 



An old optimisation to reduce the number of atomics per batch sadly
relies on struct_mutex for coordination. In order to remove struct_mutex
from serialising object/context closing, always taking and releasing an
active reference on first use / last use greatly simplifies the locking.

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: default avatarMatthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190528092956.14910-15-chris@chris-wilson.co.uk
parent 754f7a0b

drivers/gpu/drm/i915/gem/i915_gem_context.c

+1 −1
Original line number Diff line number Diff line
@@ -112,7 +112,7 @@ static void lut_close(struct i915_gem_context *ctx) 
		radix_tree_iter_delete(&ctx->handles_vma, &iter, slot);



		vma->open_count--;

		__i915_gem_object_release_unless_active(vma->obj);

		i915_vma_put(vma);

	}

	rcu_read_unlock();

}

drivers/gpu/drm/i915/gem/i915_gem_object.c

+1 −12
Original line number Diff line number Diff line
@@ -155,7 +155,7 @@ void i915_gem_close_object(struct drm_gem_object *gem, struct drm_file *file) 
		list_del(&lut->ctx_link);



		i915_lut_handle_free(lut);

		__i915_gem_object_release_unless_active(obj);

		i915_gem_object_put(obj);

	}



	mutex_unlock(&i915->drm.struct_mutex);
@@ -347,17 +347,6 @@ void i915_gem_free_object(struct drm_gem_object *gem_obj) 
	call_rcu(&obj->rcu, __i915_gem_free_object_rcu);

}



void __i915_gem_object_release_unless_active(struct drm_i915_gem_object *obj)

{

	lockdep_assert_held(&obj->base.dev->struct_mutex);



	if (!i915_gem_object_has_active_reference(obj) &&

	    i915_gem_object_is_active(obj))

		i915_gem_object_set_active_reference(obj);

	else

		i915_gem_object_put(obj);

}



static inline enum fb_op_origin

fb_write_origin(struct drm_i915_gem_object *obj, unsigned int domain)

{

drivers/gpu/drm/i915/gem/i915_gem_object.h

+1 −23
Original line number Diff line number Diff line
@@ -161,31 +161,9 @@ i915_gem_object_needs_async_cancel(const struct drm_i915_gem_object *obj) 
static inline bool

i915_gem_object_is_active(const struct drm_i915_gem_object *obj)

{

	return obj->active_count;

	return READ_ONCE(obj->active_count);

}



static inline bool

i915_gem_object_has_active_reference(const struct drm_i915_gem_object *obj)

{

	return test_bit(I915_BO_ACTIVE_REF, &obj->flags);

}



static inline void

i915_gem_object_set_active_reference(struct drm_i915_gem_object *obj)

{

	lockdep_assert_held(&obj->base.dev->struct_mutex);

	__set_bit(I915_BO_ACTIVE_REF, &obj->flags);

}



static inline void

i915_gem_object_clear_active_reference(struct drm_i915_gem_object *obj)

{

	lockdep_assert_held(&obj->base.dev->struct_mutex);

	__clear_bit(I915_BO_ACTIVE_REF, &obj->flags);

}



void __i915_gem_object_release_unless_active(struct drm_i915_gem_object *obj);



static inline bool

i915_gem_object_is_framebuffer(const struct drm_i915_gem_object *obj)

{

drivers/gpu/drm/i915/gem/i915_gem_object_types.h

+0 −8
Original line number Diff line number Diff line
@@ -120,14 +120,6 @@ struct drm_i915_gem_object { 
	struct list_head batch_pool_link;

	I915_SELFTEST_DECLARE(struct list_head st_link);



	unsigned long flags;



	/**

	 * Have we taken a reference for the object for incomplete GPU

	 * activity?

	 */

#define I915_BO_ACTIVE_REF 0



	/*

	 * Is the object to be mapped as read-only to the GPU

	 * Only honoured if hardware has relevant pte bit

drivers/gpu/drm/i915/gem/selftests/huge_pages.c

+1 −2
Original line number Diff line number Diff line
@@ -976,8 +976,6 @@ static int gpu_write(struct i915_vma *vma, 
	if (err)

		goto err_request;



	i915_gem_object_set_active_reference(batch->obj);



	i915_vma_lock(vma);

	err = i915_gem_object_set_to_gtt_domain(vma->obj, false);

	if (err == 0)
@@ -996,6 +994,7 @@ err_request: 
err_batch:

	i915_vma_unpin(batch);

	i915_vma_close(batch);

	i915_vma_put(batch);



	return err;

}

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