drm/i915: Kill the undead i915_gem_batch_pool.c

/*

 * SPDX-License-Identifier: MIT

 *

 * Copyright © 2014-2018 Intel Corporation

 */

#include "i915_gem_batch_pool.h"

#include "i915_drv.h"

/**

 * DOC: batch pool

 *

 * In order to submit batch buffers as 'secure', the software command parser

 * must ensure that a batch buffer cannot be modified after parsing. It does

 * this by copying the user provided batch buffer contents to a kernel owned

 * buffer from which the hardware will actually execute, and by carefully

 * managing the address space bindings for such buffers.

 *

 * The batch pool framework provides a mechanism for the driver to manage a

 * set of scratch buffers to use for this purpose. The framework can be

 * extended to support other uses cases should they arise.

 */

/**

 * i915_gem_batch_pool_init() - initialize a batch buffer pool

 * @pool: the batch buffer pool

 * @engine: the associated request submission engine

 */

void i915_gem_batch_pool_init(struct i915_gem_batch_pool *pool,

			      struct intel_engine_cs *engine)

{

	int n;

	pool->engine = engine;

	for (n = 0; n < ARRAY_SIZE(pool->cache_list); n++)

		INIT_LIST_HEAD(&pool->cache_list[n]);

}

/**

 * i915_gem_batch_pool_fini() - clean up a batch buffer pool

 * @pool: the pool to clean up

 *

 * Note: Callers must hold the struct_mutex.

 */

void i915_gem_batch_pool_fini(struct i915_gem_batch_pool *pool)

{

	int n;

	lockdep_assert_held(&pool->engine->i915->drm.struct_mutex);

	for (n = 0; n < ARRAY_SIZE(pool->cache_list); n++) {

		struct drm_i915_gem_object *obj, *next;

		list_for_each_entry_safe(obj, next,

					 &pool->cache_list[n],

					 batch_pool_link)

			i915_gem_object_put(obj);

		INIT_LIST_HEAD(&pool->cache_list[n]);

	}

}

/**

 * i915_gem_batch_pool_get() - allocate a buffer from the pool

 * @pool: the batch buffer pool

 * @size: the minimum desired size of the returned buffer

 *

 * Returns an inactive buffer from @pool with at least @size bytes,

 * with the pages pinned. The caller must i915_gem_object_unpin_pages()

 * on the returned object.

 *

 * Note: Callers must hold the struct_mutex

 *

 * Return: the buffer object or an error pointer

 */

struct drm_i915_gem_object *

i915_gem_batch_pool_get(struct i915_gem_batch_pool *pool,

			size_t size)

{

	struct drm_i915_gem_object *obj;

	struct list_head *list;

	int n, ret;

	lockdep_assert_held(&pool->engine->i915->drm.struct_mutex);

	/* Compute a power-of-two bucket, but throw everything greater than

	 * 16KiB into the same bucket: i.e. the the buckets hold objects of

	 * (1 page, 2 pages, 4 pages, 8+ pages).

	 */

	n = fls(size >> PAGE_SHIFT) - 1;

	if (n >= ARRAY_SIZE(pool->cache_list))

		n = ARRAY_SIZE(pool->cache_list) - 1;

	list = &pool->cache_list[n];

	list_for_each_entry(obj, list, batch_pool_link) {

		struct dma_resv *resv = obj->base.resv;

		/* The batches are strictly LRU ordered */

		if (!dma_resv_test_signaled_rcu(resv, true))

			break;

		/*

		 * The object is now idle, clear the array of shared

		 * fences before we add a new request. Although, we

		 * remain on the same engine, we may be on a different

		 * timeline and so may continually grow the array,

		 * trapping a reference to all the old fences, rather

		 * than replace the existing fence.

		 */

		if (rcu_access_pointer(resv->fence)) {

			dma_resv_lock(resv, NULL);

			dma_resv_add_excl_fence(resv, NULL);

			dma_resv_unlock(resv);

		}

		if (obj->base.size >= size)

			goto found;

	}

	obj = i915_gem_object_create_internal(pool->engine->i915, size);

	if (IS_ERR(obj))

		return obj;

found:

	ret = i915_gem_object_pin_pages(obj);

	if (ret)

		return ERR_PTR(ret);

	list_move_tail(&obj->batch_pool_link, list);

	return obj;

}