drm/i915: Replace struct_mutex for batch pool serialisation

Switch to tracking activity via i915_active on individual nodes, only
keeping a list of retired objects in the cache, and reaping the cache
when the engine itself idles.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190804124826.30272-2-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/Makefile

@@ -72,6 +72,7 @@ obj-y += gt/
 gt-y += \
 	gt/intel_breadcrumbs.o \
 	gt/intel_context.o \
+	gt/intel_engine_pool.o \
 	gt/intel_engine_cs.o \
 	gt/intel_engine_pm.o \
 	gt/intel_gt.o \
@@ -125,7 +126,6 @@ i915-y += \
 	  $(gem-y) \
 	  i915_active.o \
 	  i915_cmd_parser.o \
-	  i915_gem_batch_pool.o \
 	  i915_gem_evict.o \
 	  i915_gem_fence_reg.o \
 	  i915_gem_gtt.o \

drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c

@@ -16,6 +16,7 @@
 
 #include "gem/i915_gem_ioctls.h"
 #include "gt/intel_context.h"
+#include "gt/intel_engine_pool.h"
 #include "gt/intel_gt.h"
 #include "gt/intel_gt_pm.h"
 
@@ -1198,25 +1199,26 @@ static int __reloc_gpu_alloc(struct i915_execbuffer *eb,
 			     unsigned int len)
 {
 	struct reloc_cache *cache = &eb->reloc_cache;
-	struct drm_i915_gem_object *obj;
+	struct intel_engine_pool_node *pool;
 	struct i915_request *rq;
 	struct i915_vma *batch;
 	u32 *cmd;
 	int err;
 
-	obj = i915_gem_batch_pool_get(&eb->engine->batch_pool, PAGE_SIZE);
-	if (IS_ERR(obj))
-		return PTR_ERR(obj);
+	pool = intel_engine_pool_get(&eb->engine->pool, PAGE_SIZE);
+	if (IS_ERR(pool))
+		return PTR_ERR(pool);
 
-	cmd = i915_gem_object_pin_map(obj,
+	cmd = i915_gem_object_pin_map(pool->obj,
 				      cache->has_llc ?
 				      I915_MAP_FORCE_WB :
 				      I915_MAP_FORCE_WC);
-	i915_gem_object_unpin_pages(obj);
-	if (IS_ERR(cmd))
-		return PTR_ERR(cmd);
+	if (IS_ERR(cmd)) {
+		err = PTR_ERR(cmd);
+		goto out_pool;
+	}
 
-	batch = i915_vma_instance(obj, vma->vm, NULL);
+	batch = i915_vma_instance(pool->obj, vma->vm, NULL);
 	if (IS_ERR(batch)) {
 		err = PTR_ERR(batch);
 		goto err_unmap;
@@ -1232,6 +1234,10 @@ static int __reloc_gpu_alloc(struct i915_execbuffer *eb,
 		goto err_unpin;
 	}
 
+	err = intel_engine_pool_mark_active(pool, rq);
+	if (err)
+		goto err_request;
+
 	err = reloc_move_to_gpu(rq, vma);
 	if (err)
 		goto err_request;
@@ -1257,7 +1263,7 @@ static int __reloc_gpu_alloc(struct i915_execbuffer *eb,
 	cache->rq_size = 0;
 
 	/* Return with batch mapping (cmd) still pinned */
-	return 0;
+	goto out_pool;
 
 skip_request:
 	i915_request_skip(rq, err);
@@ -1266,7 +1272,9 @@ static int __reloc_gpu_alloc(struct i915_execbuffer *eb,
 err_unpin:
 	i915_vma_unpin(batch);
 err_unmap:
-	i915_gem_object_unpin_map(obj);
+	i915_gem_object_unpin_map(pool->obj);
+out_pool:
+	intel_engine_pool_put(pool);
 	return err;
 }
 
@@ -2010,18 +2018,17 @@ static int i915_reset_gen7_sol_offsets(struct i915_request *rq)
 
 static struct i915_vma *eb_parse(struct i915_execbuffer *eb, bool is_master)
 {
-	struct drm_i915_gem_object *shadow_batch_obj;
+	struct intel_engine_pool_node *pool;
 	struct i915_vma *vma;
 	int err;
 
-	shadow_batch_obj = i915_gem_batch_pool_get(&eb->engine->batch_pool,
-						   PAGE_ALIGN(eb->batch_len));
-	if (IS_ERR(shadow_batch_obj))
-		return ERR_CAST(shadow_batch_obj);
+	pool = intel_engine_pool_get(&eb->engine->pool, eb->batch_len);
+	if (IS_ERR(pool))
+		return ERR_CAST(pool);
 
 	err = intel_engine_cmd_parser(eb->engine,
 				      eb->batch->obj,
-				      shadow_batch_obj,
+				      pool->obj,
 				      eb->batch_start_offset,
 				      eb->batch_len,
 				      is_master);
@@ -2030,12 +2037,12 @@ static struct i915_vma *eb_parse(struct i915_execbuffer *eb, bool is_master)
 			vma = NULL;
 		else
 			vma = ERR_PTR(err);
-		goto out;
+		goto err;
 	}
 
-	vma = i915_gem_object_ggtt_pin(shadow_batch_obj, NULL, 0, 0, 0);
+	vma = i915_gem_object_ggtt_pin(pool->obj, NULL, 0, 0, 0);
 	if (IS_ERR(vma))
-		goto out;
+		goto err;
 
 	eb->vma[eb->buffer_count] = i915_vma_get(vma);
 	eb->flags[eb->buffer_count] =
@@ -2043,8 +2050,11 @@ static struct i915_vma *eb_parse(struct i915_execbuffer *eb, bool is_master)
 	vma->exec_flags = &eb->flags[eb->buffer_count];
 	eb->buffer_count++;
 
-out:
-	i915_gem_object_unpin_pages(shadow_batch_obj);
+	vma->private = pool;
+	return vma;
+
+err:
+	intel_engine_pool_put(pool);
 	return vma;
 }
 
@@ -2588,6 +2598,8 @@ i915_gem_do_execbuffer(struct drm_device *dev,
 	 * to explicitly hold another reference here.
 	 */
 	eb.request->batch = eb.batch;
+	if (eb.batch->private)
+		intel_engine_pool_mark_active(eb.batch->private, eb.request);
 
 	trace_i915_request_queue(eb.request, eb.batch_flags);
 	err = eb_submit(&eb);
@@ -2612,6 +2624,8 @@ i915_gem_do_execbuffer(struct drm_device *dev,
 err_batch_unpin:
 	if (eb.batch_flags & I915_DISPATCH_SECURE)
 		i915_vma_unpin(eb.batch);
+	if (eb.batch->private)
+		intel_engine_pool_put(eb.batch->private);
 err_vma:
 	if (eb.exec)
 		eb_release_vmas(&eb);

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

@@ -66,7 +66,6 @@ void i915_gem_object_init(struct drm_i915_gem_object *obj,
 	INIT_LIST_HEAD(&obj->mm.link);
 
 	INIT_LIST_HEAD(&obj->lut_list);
-	INIT_LIST_HEAD(&obj->batch_pool_link);
 
 	init_rcu_head(&obj->rcu);
 

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

@@ -114,7 +114,6 @@ struct drm_i915_gem_object {
 	unsigned int userfault_count;
 	struct list_head userfault_link;
 
-	struct list_head batch_pool_link;
 	I915_SELFTEST_DECLARE(struct list_head st_link);
 
 	/*

drivers/gpu/drm/i915/gem/i915_gem_pm.c

@@ -34,10 +34,8 @@ static void i915_gem_park(struct drm_i915_private *i915)
 
 	lockdep_assert_held(&i915->drm.struct_mutex);
 
-	for_each_engine(engine, i915, id) {
+	for_each_engine(engine, i915, id)
 		call_idle_barriers(engine); /* cleanup after wedging */
-		i915_gem_batch_pool_fini(&engine->batch_pool);
-	}
 
 	intel_timelines_park(i915);
 	i915_vma_parked(i915);

drivers/gpu/drm/i915/gt/intel_engine.h

@@ -9,7 +9,6 @@
 #include <linux/random.h>
 #include <linux/seqlock.h>
 
-#include "i915_gem_batch_pool.h"
 #include "i915_pmu.h"
 #include "i915_reg.h"
 #include "i915_request.h"

drivers/gpu/drm/i915/gt/intel_engine_cs.c

@@ -32,6 +32,7 @@
 
 #include "intel_engine.h"
 #include "intel_engine_pm.h"
+#include "intel_engine_pool.h"
 #include "intel_context.h"
 #include "intel_lrc.h"
 #include "intel_reset.h"
@@ -492,11 +493,6 @@ int intel_engines_init(struct drm_i915_private *i915)
 	return err;
 }
 
-static void intel_engine_init_batch_pool(struct intel_engine_cs *engine)
-{
-	i915_gem_batch_pool_init(&engine->batch_pool, engine);
-}
-
 void intel_engine_init_execlists(struct intel_engine_cs *engine)
 {
 	struct intel_engine_execlists * const execlists = &engine->execlists;
@@ -622,10 +618,11 @@ static int intel_engine_setup_common(struct intel_engine_cs *engine)
 	intel_engine_init_breadcrumbs(engine);
 	intel_engine_init_execlists(engine);
 	intel_engine_init_hangcheck(engine);
-	intel_engine_init_batch_pool(engine);
 	intel_engine_init_cmd_parser(engine);
 	intel_engine_init__pm(engine);
 
+	intel_engine_pool_init(&engine->pool);
+
 	/* Use the whole device by default */
 	engine->sseu =
 		intel_sseu_from_device_info(&RUNTIME_INFO(engine->i915)->sseu);
@@ -869,9 +866,9 @@ void intel_engine_cleanup_common(struct intel_engine_cs *engine)
 
 	cleanup_status_page(engine);
 
+	intel_engine_pool_fini(&engine->pool);
 	intel_engine_fini_breadcrumbs(engine);
 	intel_engine_cleanup_cmd_parser(engine);
-	i915_gem_batch_pool_fini(&engine->batch_pool);
 
 	if (engine->default_state)
 		i915_gem_object_put(engine->default_state);

drivers/gpu/drm/i915/gt/intel_engine_pm.c

@@ -8,6 +8,7 @@
 
 #include "intel_engine.h"
 #include "intel_engine_pm.h"
+#include "intel_engine_pool.h"
 #include "intel_gt.h"
 #include "intel_gt_pm.h"
 
@@ -116,6 +117,7 @@ static int __engine_park(struct intel_wakeref *wf)
 	GEM_TRACE("%s\n", engine->name);
 
 	intel_engine_disarm_breadcrumbs(engine);
+	intel_engine_pool_park(&engine->pool);
 
 	/* Must be reset upon idling, or we may miss the busy wakeup. */
 	GEM_BUG_ON(engine->execlists.queue_priority_hint != INT_MIN);

drivers/gpu/drm/i915/gt/intel_engine_pool.c

+/*
+ * SPDX-License-Identifier: MIT
+ *
+ * Copyright © 2014-2018 Intel Corporation
+ */
+
+#include "gem/i915_gem_object.h"
+
+#include "i915_drv.h"
+#include "intel_engine_pm.h"
+#include "intel_engine_pool.h"
+
+static struct intel_engine_cs *to_engine(struct intel_engine_pool *pool)
+{
+	return container_of(pool, struct intel_engine_cs, pool);
+}
+
+static struct list_head *
+bucket_for_size(struct intel_engine_pool *pool, size_t sz)
+{
+	int n;
+
+	/*
+	 * Compute a power-of-two bucket, but throw everything greater than
+	 * 16KiB into the same bucket: i.e. the buckets hold objects of
+	 * (1 page, 2 pages, 4 pages, 8+ pages).
+	 */
+	n = fls(sz >> PAGE_SHIFT) - 1;
+	if (n >= ARRAY_SIZE(pool->cache_list))
+		n = ARRAY_SIZE(pool->cache_list) - 1;
+
+	return &pool->cache_list[n];
+}
+
+static void node_free(struct intel_engine_pool_node *node)
+{
+	i915_gem_object_put(node->obj);
+	i915_active_fini(&node->active);
+	kfree(node);
+}
+
+static int pool_active(struct i915_active *ref)
+{
+	struct intel_engine_pool_node *node =
+		container_of(ref, typeof(*node), active);
+	struct reservation_object *resv = node->obj->base.resv;
+	int err;
+
+	if (reservation_object_trylock(resv)) {
+		reservation_object_add_excl_fence(resv, NULL);
+		reservation_object_unlock(resv);
+	}
+
+	err = i915_gem_object_pin_pages(node->obj);
+	if (err)
+		return err;
+
+	/* Hide this pinned object from the shrinker until retired */
+	i915_gem_object_make_unshrinkable(node->obj);
+
+	return 0;
+}
+
+static void pool_retire(struct i915_active *ref)
+{
+	struct intel_engine_pool_node *node =
+		container_of(ref, typeof(*node), active);
+	struct intel_engine_pool *pool = node->pool;
+	struct list_head *list = bucket_for_size(pool, node->obj->base.size);
+	unsigned long flags;
+
+	GEM_BUG_ON(!intel_engine_pm_is_awake(to_engine(pool)));
+
+	i915_gem_object_unpin_pages(node->obj);
+
+	/* Return this object to the shrinker pool */
+	i915_gem_object_make_purgeable(node->obj);
+
+	spin_lock_irqsave(&pool->lock, flags);
+	list_add(&node->link, list);
+	spin_unlock_irqrestore(&pool->lock, flags);
+}
+
+static struct intel_engine_pool_node *
+node_create(struct intel_engine_pool *pool, size_t sz)
+{
+	struct intel_engine_cs *engine = to_engine(pool);
+	struct intel_engine_pool_node *node;
+	struct drm_i915_gem_object *obj;
+
+	node = kmalloc(sizeof(*node),
+		       GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_NOWARN);
+	if (!node)
+		return ERR_PTR(-ENOMEM);
+
+	node->pool = pool;
+	i915_active_init(engine->i915, &node->active, pool_active, pool_retire);
+
+	obj = i915_gem_object_create_internal(engine->i915, sz);
+	if (IS_ERR(obj)) {
+		i915_active_fini(&node->active);
+		kfree(node);
+		return ERR_CAST(obj);
+	}
+
+	node->obj = obj;
+	return node;
+}
+
+struct intel_engine_pool_node *
+intel_engine_pool_get(struct intel_engine_pool *pool, size_t size)
+{
+	struct intel_engine_pool_node *node;
+	struct list_head *list;
+	unsigned long flags;
+	int ret;
+
+	GEM_BUG_ON(!intel_engine_pm_is_awake(to_engine(pool)));
+
+	size = PAGE_ALIGN(size);
+	list = bucket_for_size(pool, size);
+
+	spin_lock_irqsave(&pool->lock, flags);
+	list_for_each_entry(node, list, link) {
+		if (node->obj->base.size < size)
+			continue;
+		list_del(&node->link);
+		break;
+	}
+	spin_unlock_irqrestore(&pool->lock, flags);
+
+	if (&node->link == list) {
+		node = node_create(pool, size);
+		if (IS_ERR(node))
+			return node;
+	}
+
+	ret = i915_active_acquire(&node->active);
+	if (ret) {
+		node_free(node);
+		return ERR_PTR(ret);
+	}
+
+	return node;
+}
+
+void intel_engine_pool_init(struct intel_engine_pool *pool)
+{
+	int n;
+
+	spin_lock_init(&pool->lock);
+	for (n = 0; n < ARRAY_SIZE(pool->cache_list); n++)
+		INIT_LIST_HEAD(&pool->cache_list[n]);
+}
+
+void intel_engine_pool_park(struct intel_engine_pool *pool)
+{
+	int n;
+
+	for (n = 0; n < ARRAY_SIZE(pool->cache_list); n++) {
+		struct list_head *list = &pool->cache_list[n];
+		struct intel_engine_pool_node *node, *nn;
+
+		list_for_each_entry_safe(node, nn, list, link)
+			node_free(node);
+
+		INIT_LIST_HEAD(list);
+	}
+}
+
+void intel_engine_pool_fini(struct intel_engine_pool *pool)
+{
+	int n;
+
+	for (n = 0; n < ARRAY_SIZE(pool->cache_list); n++)
+		GEM_BUG_ON(!list_empty(&pool->cache_list[n]));
+}

drivers/gpu/drm/i915/gt/intel_engine_pool.h

+/*
+ * SPDX-License-Identifier: MIT
+ *
+ * Copyright © 2014-2018 Intel Corporation
+ */
+
+#ifndef INTEL_ENGINE_POOL_H
+#define INTEL_ENGINE_POOL_H
+
+#include "intel_engine_pool_types.h"
+#include "i915_active.h"
+#include "i915_request.h"
+
+struct intel_engine_pool_node *
+intel_engine_pool_get(struct intel_engine_pool *pool, size_t size);
+
+static inline int
+intel_engine_pool_mark_active(struct intel_engine_pool_node *node,
+			      struct i915_request *rq)
+{
+	return i915_active_ref(&node->active, rq->fence.context, rq);
+}
+
+static inline void
+intel_engine_pool_put(struct intel_engine_pool_node *node)
+{
+	i915_active_release(&node->active);
+}
+
+void intel_engine_pool_init(struct intel_engine_pool *pool);
+void intel_engine_pool_park(struct intel_engine_pool *pool);
+void intel_engine_pool_fini(struct intel_engine_pool *pool);
+
+#endif /* INTEL_ENGINE_POOL_H */

drivers/gpu/drm/i915/gt/intel_engine_pool_types.h

+/*
+ * SPDX-License-Identifier: MIT
+ *
+ * Copyright © 2014-2018 Intel Corporation
+ */
+
+#ifndef INTEL_ENGINE_POOL_TYPES_H
+#define INTEL_ENGINE_POOL_TYPES_H
+
+#include <linux/list.h>
+#include <linux/spinlock.h>
+
+#include "i915_active_types.h"
+
+struct drm_i915_gem_object;
+
+struct intel_engine_pool {
+	spinlock_t lock;
+	struct list_head cache_list[4];
+};
+
+struct intel_engine_pool_node {
+	struct i915_active active;
+	struct drm_i915_gem_object *obj;
+	struct list_head link;
+	struct intel_engine_pool *pool;
+};
+
+#endif /* INTEL_ENGINE_POOL_TYPES_H */

drivers/gpu/drm/i915/gt/intel_engine_types.h

@@ -16,12 +16,12 @@
 #include <linux/types.h>
 
 #include "i915_gem.h"
-#include "i915_gem_batch_pool.h"
 #include "i915_pmu.h"
 #include "i915_priolist_types.h"
 #include "i915_selftest.h"
-#include "gt/intel_timeline_types.h"
+#include "intel_engine_pool_types.h"
 #include "intel_sseu.h"
+#include "intel_timeline_types.h"
 #include "intel_wakeref.h"
 #include "intel_workarounds_types.h"
 
@@ -354,7 +354,7 @@ struct intel_engine_cs {
 	 * when the command parser is enabled. Prevents the client from
 	 * modifying the batch contents after software parsing.
 	 */
-	struct i915_gem_batch_pool batch_pool;
+	struct intel_engine_pool pool;
 
 	struct intel_hw_status_page status_page;
 	struct i915_ctx_workarounds wa_ctx;

drivers/gpu/drm/i915/gt/mock_engine.c

@@ -27,6 +27,7 @@
 #include "i915_drv.h"
 #include "intel_context.h"
 #include "intel_engine_pm.h"
+#include "intel_engine_pool.h"
 
 #include "mock_engine.h"
 #include "selftests/mock_request.h"
@@ -292,6 +293,7 @@ int mock_engine_init(struct intel_engine_cs *engine)
 	intel_engine_init_breadcrumbs(engine);
 	intel_engine_init_execlists(engine);
 	intel_engine_init__pm(engine);
+	intel_engine_pool_init(&engine->pool);
 
 	engine->kernel_context =
 		i915_gem_context_get_engine(i915->kernel_context, engine->id);

drivers/gpu/drm/i915/i915_debugfs.c

@@ -295,27 +295,6 @@ static int per_file_stats(int id, void *ptr, void *data)
 			   stats.closed); \
 } while (0)
 
-static void print_batch_pool_stats(struct seq_file *m,
-				   struct drm_i915_private *dev_priv)
-{
-	struct drm_i915_gem_object *obj;
-	struct intel_engine_cs *engine;
-	struct file_stats stats = {};
-	enum intel_engine_id id;
-	int j;
-
-	for_each_engine(engine, dev_priv, id) {
-		for (j = 0; j < ARRAY_SIZE(engine->batch_pool.cache_list); j++) {
-			list_for_each_entry(obj,
-					    &engine->batch_pool.cache_list[j],
-					    batch_pool_link)
-				per_file_stats(0, obj, &stats);
-		}
-	}
-
-	print_file_stats(m, "[k]batch pool", stats);
-}
-
 static void print_context_stats(struct seq_file *m,
 				struct drm_i915_private *i915)
 {
@@ -374,58 +353,12 @@ static int i915_gem_object_info(struct seq_file *m, void *data)
 	if (ret)
 		return ret;
 
-	print_batch_pool_stats(m, i915);
 	print_context_stats(m, i915);
 	mutex_unlock(&i915->drm.struct_mutex);
 
 	return 0;
 }
 
-static int i915_gem_batch_pool_info(struct seq_file *m, void *data)
-{
-	struct drm_i915_private *dev_priv = node_to_i915(m->private);
-	struct drm_device *dev = &dev_priv->drm;
-	struct drm_i915_gem_object *obj;
-	struct intel_engine_cs *engine;
-	enum intel_engine_id id;
-	int total = 0;
-	int ret, j;
-
-	ret = mutex_lock_interruptible(&dev->struct_mutex);
-	if (ret)
-		return ret;
-
-	for_each_engine(engine, dev_priv, id) {
-		for (j = 0; j < ARRAY_SIZE(engine->batch_pool.cache_list); j++) {
-			int count;
-
-			count = 0;
-			list_for_each_entry(obj,
-					    &engine->batch_pool.cache_list[j],
-					    batch_pool_link)
-				count++;
-			seq_printf(m, "%s cache[%d]: %d objects\n",
-				   engine->name, j, count);
-
-			list_for_each_entry(obj,
-					    &engine->batch_pool.cache_list[j],
-					    batch_pool_link) {
-				seq_puts(m, "   ");
-				describe_obj(m, obj);
-				seq_putc(m, '\n');
-			}
-
-			total += count;
-		}
-	}
-
-	seq_printf(m, "total: %d\n", total);
-
-	mutex_unlock(&dev->struct_mutex);
-
-	return 0;
-}
-
 static void gen8_display_interrupt_info(struct seq_file *m)
 {
 	struct drm_i915_private *dev_priv = node_to_i915(m->private);
@@ -4385,7 +4318,6 @@ static const struct drm_info_list i915_debugfs_list[] = {
 	{"i915_gem_objects", i915_gem_object_info, 0},
 	{"i915_gem_fence_regs", i915_gem_fence_regs_info, 0},
 	{"i915_gem_interrupt", i915_interrupt_info, 0},
-	{"i915_gem_batch_pool", i915_gem_batch_pool_info, 0},
 	{"i915_guc_info", i915_guc_info, 0},
 	{"i915_guc_load_status", i915_guc_load_status_info, 0},
 	{"i915_guc_log_dump", i915_guc_log_dump, 0},

drivers/gpu/drm/i915/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 reservation_object *resv = obj->base.resv;
-
-		/* The batches are strictly LRU ordered */
-		if (!reservation_object_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)) {
-			reservation_object_lock(resv, NULL);
-			reservation_object_add_excl_fence(resv, NULL);
-			reservation_object_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;
-}

drivers/gpu/drm/i915/i915_gem_batch_pool.h

-/*
- * SPDX-License-Identifier: MIT
- *
- * Copyright © 2014-2018 Intel Corporation
- */
-
-#ifndef I915_GEM_BATCH_POOL_H
-#define I915_GEM_BATCH_POOL_H
-
-#include <linux/types.h>
-
-struct drm_i915_gem_object;
-struct intel_engine_cs;
-
-struct i915_gem_batch_pool {
-	struct intel_engine_cs *engine;
-	struct list_head cache_list[4];
-};
-
-void i915_gem_batch_pool_init(struct i915_gem_batch_pool *pool,
-			      struct intel_engine_cs *engine);
-void i915_gem_batch_pool_fini(struct i915_gem_batch_pool *pool);
-struct drm_i915_gem_object *
-i915_gem_batch_pool_get(struct i915_gem_batch_pool *pool, size_t size);
-
-#endif /* I915_GEM_BATCH_POOL_H */