xref: /openbmc/linux/drivers/gpu/drm/qxl/qxl_cmd.c (revision 0edbfea5)
1 /*
2  * Copyright 2013 Red Hat Inc.
3  *
4  * Permission is hereby granted, free of charge, to any person obtaining a
5  * copy of this software and associated documentation files (the "Software"),
6  * to deal in the Software without restriction, including without limitation
7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8  * and/or sell copies of the Software, and to permit persons to whom the
9  * Software is furnished to do so, subject to the following conditions:
10  *
11  * The above copyright notice and this permission notice shall be included in
12  * all copies or substantial portions of the Software.
13  *
14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
17  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
18  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
19  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
20  * OTHER DEALINGS IN THE SOFTWARE.
21  *
22  * Authors: Dave Airlie
23  *          Alon Levy
24  */
25 
26 /* QXL cmd/ring handling */
27 
28 #include "qxl_drv.h"
29 #include "qxl_object.h"
30 
31 static int qxl_reap_surface_id(struct qxl_device *qdev, int max_to_reap);
32 
33 struct ring {
34 	struct qxl_ring_header      header;
35 	uint8_t                     elements[0];
36 };
37 
38 struct qxl_ring {
39 	struct ring	       *ring;
40 	int			element_size;
41 	int			n_elements;
42 	int			prod_notify;
43 	wait_queue_head_t      *push_event;
44 	spinlock_t             lock;
45 };
46 
47 void qxl_ring_free(struct qxl_ring *ring)
48 {
49 	kfree(ring);
50 }
51 
52 void qxl_ring_init_hdr(struct qxl_ring *ring)
53 {
54 	ring->ring->header.notify_on_prod = ring->n_elements;
55 }
56 
57 struct qxl_ring *
58 qxl_ring_create(struct qxl_ring_header *header,
59 		int element_size,
60 		int n_elements,
61 		int prod_notify,
62 		bool set_prod_notify,
63 		wait_queue_head_t *push_event)
64 {
65 	struct qxl_ring *ring;
66 
67 	ring = kmalloc(sizeof(*ring), GFP_KERNEL);
68 	if (!ring)
69 		return NULL;
70 
71 	ring->ring = (struct ring *)header;
72 	ring->element_size = element_size;
73 	ring->n_elements = n_elements;
74 	ring->prod_notify = prod_notify;
75 	ring->push_event = push_event;
76 	if (set_prod_notify)
77 		qxl_ring_init_hdr(ring);
78 	spin_lock_init(&ring->lock);
79 	return ring;
80 }
81 
82 static int qxl_check_header(struct qxl_ring *ring)
83 {
84 	int ret;
85 	struct qxl_ring_header *header = &(ring->ring->header);
86 	unsigned long flags;
87 	spin_lock_irqsave(&ring->lock, flags);
88 	ret = header->prod - header->cons < header->num_items;
89 	if (ret == 0)
90 		header->notify_on_cons = header->cons + 1;
91 	spin_unlock_irqrestore(&ring->lock, flags);
92 	return ret;
93 }
94 
95 int qxl_check_idle(struct qxl_ring *ring)
96 {
97 	int ret;
98 	struct qxl_ring_header *header = &(ring->ring->header);
99 	unsigned long flags;
100 	spin_lock_irqsave(&ring->lock, flags);
101 	ret = header->prod == header->cons;
102 	spin_unlock_irqrestore(&ring->lock, flags);
103 	return ret;
104 }
105 
106 int qxl_ring_push(struct qxl_ring *ring,
107 		  const void *new_elt, bool interruptible)
108 {
109 	struct qxl_ring_header *header = &(ring->ring->header);
110 	uint8_t *elt;
111 	int idx, ret;
112 	unsigned long flags;
113 	spin_lock_irqsave(&ring->lock, flags);
114 	if (header->prod - header->cons == header->num_items) {
115 		header->notify_on_cons = header->cons + 1;
116 		mb();
117 		spin_unlock_irqrestore(&ring->lock, flags);
118 		if (!drm_can_sleep()) {
119 			while (!qxl_check_header(ring))
120 				udelay(1);
121 		} else {
122 			if (interruptible) {
123 				ret = wait_event_interruptible(*ring->push_event,
124 							       qxl_check_header(ring));
125 				if (ret)
126 					return ret;
127 			} else {
128 				wait_event(*ring->push_event,
129 					   qxl_check_header(ring));
130 			}
131 
132 		}
133 		spin_lock_irqsave(&ring->lock, flags);
134 	}
135 
136 	idx = header->prod & (ring->n_elements - 1);
137 	elt = ring->ring->elements + idx * ring->element_size;
138 
139 	memcpy((void *)elt, new_elt, ring->element_size);
140 
141 	header->prod++;
142 
143 	mb();
144 
145 	if (header->prod == header->notify_on_prod)
146 		outb(0, ring->prod_notify);
147 
148 	spin_unlock_irqrestore(&ring->lock, flags);
149 	return 0;
150 }
151 
152 static bool qxl_ring_pop(struct qxl_ring *ring,
153 			 void *element)
154 {
155 	volatile struct qxl_ring_header *header = &(ring->ring->header);
156 	volatile uint8_t *ring_elt;
157 	int idx;
158 	unsigned long flags;
159 	spin_lock_irqsave(&ring->lock, flags);
160 	if (header->cons == header->prod) {
161 		header->notify_on_prod = header->cons + 1;
162 		spin_unlock_irqrestore(&ring->lock, flags);
163 		return false;
164 	}
165 
166 	idx = header->cons & (ring->n_elements - 1);
167 	ring_elt = ring->ring->elements + idx * ring->element_size;
168 
169 	memcpy(element, (void *)ring_elt, ring->element_size);
170 
171 	header->cons++;
172 
173 	spin_unlock_irqrestore(&ring->lock, flags);
174 	return true;
175 }
176 
177 int
178 qxl_push_command_ring_release(struct qxl_device *qdev, struct qxl_release *release,
179 			      uint32_t type, bool interruptible)
180 {
181 	struct qxl_command cmd;
182 	struct qxl_bo_list *entry = list_first_entry(&release->bos, struct qxl_bo_list, tv.head);
183 
184 	cmd.type = type;
185 	cmd.data = qxl_bo_physical_address(qdev, to_qxl_bo(entry->tv.bo), release->release_offset);
186 
187 	return qxl_ring_push(qdev->command_ring, &cmd, interruptible);
188 }
189 
190 int
191 qxl_push_cursor_ring_release(struct qxl_device *qdev, struct qxl_release *release,
192 			     uint32_t type, bool interruptible)
193 {
194 	struct qxl_command cmd;
195 	struct qxl_bo_list *entry = list_first_entry(&release->bos, struct qxl_bo_list, tv.head);
196 
197 	cmd.type = type;
198 	cmd.data = qxl_bo_physical_address(qdev, to_qxl_bo(entry->tv.bo), release->release_offset);
199 
200 	return qxl_ring_push(qdev->cursor_ring, &cmd, interruptible);
201 }
202 
203 bool qxl_queue_garbage_collect(struct qxl_device *qdev, bool flush)
204 {
205 	if (!qxl_check_idle(qdev->release_ring)) {
206 		queue_work(qdev->gc_queue, &qdev->gc_work);
207 		if (flush)
208 			flush_work(&qdev->gc_work);
209 		return true;
210 	}
211 	return false;
212 }
213 
214 int qxl_garbage_collect(struct qxl_device *qdev)
215 {
216 	struct qxl_release *release;
217 	uint64_t id, next_id;
218 	int i = 0;
219 	union qxl_release_info *info;
220 
221 	while (qxl_ring_pop(qdev->release_ring, &id)) {
222 		QXL_INFO(qdev, "popped %lld\n", id);
223 		while (id) {
224 			release = qxl_release_from_id_locked(qdev, id);
225 			if (release == NULL)
226 				break;
227 
228 			info = qxl_release_map(qdev, release);
229 			next_id = info->next;
230 			qxl_release_unmap(qdev, release, info);
231 
232 			QXL_INFO(qdev, "popped %lld, next %lld\n", id,
233 				next_id);
234 
235 			switch (release->type) {
236 			case QXL_RELEASE_DRAWABLE:
237 			case QXL_RELEASE_SURFACE_CMD:
238 			case QXL_RELEASE_CURSOR_CMD:
239 				break;
240 			default:
241 				DRM_ERROR("unexpected release type\n");
242 				break;
243 			}
244 			id = next_id;
245 
246 			qxl_release_free(qdev, release);
247 			++i;
248 		}
249 	}
250 
251 	QXL_INFO(qdev, "%s: %d\n", __func__, i);
252 
253 	return i;
254 }
255 
256 int qxl_alloc_bo_reserved(struct qxl_device *qdev,
257 			  struct qxl_release *release,
258 			  unsigned long size,
259 			  struct qxl_bo **_bo)
260 {
261 	struct qxl_bo *bo;
262 	int ret;
263 
264 	ret = qxl_bo_create(qdev, size, false /* not kernel - device */,
265 			    false, QXL_GEM_DOMAIN_VRAM, NULL, &bo);
266 	if (ret) {
267 		DRM_ERROR("failed to allocate VRAM BO\n");
268 		return ret;
269 	}
270 	ret = qxl_release_list_add(release, bo);
271 	if (ret)
272 		goto out_unref;
273 
274 	*_bo = bo;
275 	return 0;
276 out_unref:
277 	qxl_bo_unref(&bo);
278 	return ret;
279 }
280 
281 static int wait_for_io_cmd_user(struct qxl_device *qdev, uint8_t val, long port, bool intr)
282 {
283 	int irq_num;
284 	long addr = qdev->io_base + port;
285 	int ret;
286 
287 	mutex_lock(&qdev->async_io_mutex);
288 	irq_num = atomic_read(&qdev->irq_received_io_cmd);
289 	if (qdev->last_sent_io_cmd > irq_num) {
290 		if (intr)
291 			ret = wait_event_interruptible_timeout(qdev->io_cmd_event,
292 							       atomic_read(&qdev->irq_received_io_cmd) > irq_num, 5*HZ);
293 		else
294 			ret = wait_event_timeout(qdev->io_cmd_event,
295 						 atomic_read(&qdev->irq_received_io_cmd) > irq_num, 5*HZ);
296 		/* 0 is timeout, just bail the "hw" has gone away */
297 		if (ret <= 0)
298 			goto out;
299 		irq_num = atomic_read(&qdev->irq_received_io_cmd);
300 	}
301 	outb(val, addr);
302 	qdev->last_sent_io_cmd = irq_num + 1;
303 	if (intr)
304 		ret = wait_event_interruptible_timeout(qdev->io_cmd_event,
305 						       atomic_read(&qdev->irq_received_io_cmd) > irq_num, 5*HZ);
306 	else
307 		ret = wait_event_timeout(qdev->io_cmd_event,
308 					 atomic_read(&qdev->irq_received_io_cmd) > irq_num, 5*HZ);
309 out:
310 	if (ret > 0)
311 		ret = 0;
312 	mutex_unlock(&qdev->async_io_mutex);
313 	return ret;
314 }
315 
316 static void wait_for_io_cmd(struct qxl_device *qdev, uint8_t val, long port)
317 {
318 	int ret;
319 
320 restart:
321 	ret = wait_for_io_cmd_user(qdev, val, port, false);
322 	if (ret == -ERESTARTSYS)
323 		goto restart;
324 }
325 
326 int qxl_io_update_area(struct qxl_device *qdev, struct qxl_bo *surf,
327 			const struct qxl_rect *area)
328 {
329 	int surface_id;
330 	uint32_t surface_width, surface_height;
331 	int ret;
332 
333 	if (!surf->hw_surf_alloc)
334 		DRM_ERROR("got io update area with no hw surface\n");
335 
336 	if (surf->is_primary)
337 		surface_id = 0;
338 	else
339 		surface_id = surf->surface_id;
340 	surface_width = surf->surf.width;
341 	surface_height = surf->surf.height;
342 
343 	if (area->left < 0 || area->top < 0 ||
344 	    area->right > surface_width || area->bottom > surface_height) {
345 		qxl_io_log(qdev, "%s: not doing area update for "
346 			   "%d, (%d,%d,%d,%d) (%d,%d)\n", __func__, surface_id, area->left,
347 			   area->top, area->right, area->bottom, surface_width, surface_height);
348 		return -EINVAL;
349 	}
350 	mutex_lock(&qdev->update_area_mutex);
351 	qdev->ram_header->update_area = *area;
352 	qdev->ram_header->update_surface = surface_id;
353 	ret = wait_for_io_cmd_user(qdev, 0, QXL_IO_UPDATE_AREA_ASYNC, true);
354 	mutex_unlock(&qdev->update_area_mutex);
355 	return ret;
356 }
357 
358 void qxl_io_notify_oom(struct qxl_device *qdev)
359 {
360 	outb(0, qdev->io_base + QXL_IO_NOTIFY_OOM);
361 }
362 
363 void qxl_io_flush_release(struct qxl_device *qdev)
364 {
365 	outb(0, qdev->io_base + QXL_IO_FLUSH_RELEASE);
366 }
367 
368 void qxl_io_flush_surfaces(struct qxl_device *qdev)
369 {
370 	wait_for_io_cmd(qdev, 0, QXL_IO_FLUSH_SURFACES_ASYNC);
371 }
372 
373 
374 void qxl_io_destroy_primary(struct qxl_device *qdev)
375 {
376 	wait_for_io_cmd(qdev, 0, QXL_IO_DESTROY_PRIMARY_ASYNC);
377 }
378 
379 void qxl_io_create_primary(struct qxl_device *qdev,
380 			   unsigned offset, struct qxl_bo *bo)
381 {
382 	struct qxl_surface_create *create;
383 
384 	QXL_INFO(qdev, "%s: qdev %p, ram_header %p\n", __func__, qdev,
385 		 qdev->ram_header);
386 	create = &qdev->ram_header->create_surface;
387 	create->format = bo->surf.format;
388 	create->width = bo->surf.width;
389 	create->height = bo->surf.height;
390 	create->stride = bo->surf.stride;
391 	create->mem = qxl_bo_physical_address(qdev, bo, offset);
392 
393 	QXL_INFO(qdev, "%s: mem = %llx, from %p\n", __func__, create->mem,
394 		 bo->kptr);
395 
396 	create->flags = QXL_SURF_FLAG_KEEP_DATA;
397 	create->type = QXL_SURF_TYPE_PRIMARY;
398 
399 	wait_for_io_cmd(qdev, 0, QXL_IO_CREATE_PRIMARY_ASYNC);
400 }
401 
402 void qxl_io_memslot_add(struct qxl_device *qdev, uint8_t id)
403 {
404 	QXL_INFO(qdev, "qxl_memslot_add %d\n", id);
405 	wait_for_io_cmd(qdev, id, QXL_IO_MEMSLOT_ADD_ASYNC);
406 }
407 
408 void qxl_io_log(struct qxl_device *qdev, const char *fmt, ...)
409 {
410 	va_list args;
411 
412 	va_start(args, fmt);
413 	vsnprintf(qdev->ram_header->log_buf, QXL_LOG_BUF_SIZE, fmt, args);
414 	va_end(args);
415 	/*
416 	 * DO not do a DRM output here - this will call printk, which will
417 	 * call back into qxl for rendering (qxl_fb)
418 	 */
419 	outb(0, qdev->io_base + QXL_IO_LOG);
420 }
421 
422 void qxl_io_reset(struct qxl_device *qdev)
423 {
424 	outb(0, qdev->io_base + QXL_IO_RESET);
425 }
426 
427 void qxl_io_monitors_config(struct qxl_device *qdev)
428 {
429 	qxl_io_log(qdev, "%s: %d [%dx%d+%d+%d]\n", __func__,
430 		   qdev->monitors_config ?
431 		   qdev->monitors_config->count : -1,
432 		   qdev->monitors_config && qdev->monitors_config->count ?
433 		   qdev->monitors_config->heads[0].width : -1,
434 		   qdev->monitors_config && qdev->monitors_config->count ?
435 		   qdev->monitors_config->heads[0].height : -1,
436 		   qdev->monitors_config && qdev->monitors_config->count ?
437 		   qdev->monitors_config->heads[0].x : -1,
438 		   qdev->monitors_config && qdev->monitors_config->count ?
439 		   qdev->monitors_config->heads[0].y : -1
440 		   );
441 
442 	wait_for_io_cmd(qdev, 0, QXL_IO_MONITORS_CONFIG_ASYNC);
443 }
444 
445 int qxl_surface_id_alloc(struct qxl_device *qdev,
446 		      struct qxl_bo *surf)
447 {
448 	uint32_t handle;
449 	int idr_ret;
450 	int count = 0;
451 again:
452 	idr_preload(GFP_ATOMIC);
453 	spin_lock(&qdev->surf_id_idr_lock);
454 	idr_ret = idr_alloc(&qdev->surf_id_idr, NULL, 1, 0, GFP_NOWAIT);
455 	spin_unlock(&qdev->surf_id_idr_lock);
456 	idr_preload_end();
457 	if (idr_ret < 0)
458 		return idr_ret;
459 	handle = idr_ret;
460 
461 	if (handle >= qdev->rom->n_surfaces) {
462 		count++;
463 		spin_lock(&qdev->surf_id_idr_lock);
464 		idr_remove(&qdev->surf_id_idr, handle);
465 		spin_unlock(&qdev->surf_id_idr_lock);
466 		qxl_reap_surface_id(qdev, 2);
467 		goto again;
468 	}
469 	surf->surface_id = handle;
470 
471 	spin_lock(&qdev->surf_id_idr_lock);
472 	qdev->last_alloced_surf_id = handle;
473 	spin_unlock(&qdev->surf_id_idr_lock);
474 	return 0;
475 }
476 
477 void qxl_surface_id_dealloc(struct qxl_device *qdev,
478 			    uint32_t surface_id)
479 {
480 	spin_lock(&qdev->surf_id_idr_lock);
481 	idr_remove(&qdev->surf_id_idr, surface_id);
482 	spin_unlock(&qdev->surf_id_idr_lock);
483 }
484 
485 int qxl_hw_surface_alloc(struct qxl_device *qdev,
486 			 struct qxl_bo *surf,
487 			 struct ttm_mem_reg *new_mem)
488 {
489 	struct qxl_surface_cmd *cmd;
490 	struct qxl_release *release;
491 	int ret;
492 
493 	if (surf->hw_surf_alloc)
494 		return 0;
495 
496 	ret = qxl_alloc_surface_release_reserved(qdev, QXL_SURFACE_CMD_CREATE,
497 						 NULL,
498 						 &release);
499 	if (ret)
500 		return ret;
501 
502 	ret = qxl_release_reserve_list(release, true);
503 	if (ret)
504 		return ret;
505 
506 	cmd = (struct qxl_surface_cmd *)qxl_release_map(qdev, release);
507 	cmd->type = QXL_SURFACE_CMD_CREATE;
508 	cmd->flags = QXL_SURF_FLAG_KEEP_DATA;
509 	cmd->u.surface_create.format = surf->surf.format;
510 	cmd->u.surface_create.width = surf->surf.width;
511 	cmd->u.surface_create.height = surf->surf.height;
512 	cmd->u.surface_create.stride = surf->surf.stride;
513 	if (new_mem) {
514 		int slot_id = surf->type == QXL_GEM_DOMAIN_VRAM ? qdev->main_mem_slot : qdev->surfaces_mem_slot;
515 		struct qxl_memslot *slot = &(qdev->mem_slots[slot_id]);
516 
517 		/* TODO - need to hold one of the locks to read tbo.offset */
518 		cmd->u.surface_create.data = slot->high_bits;
519 
520 		cmd->u.surface_create.data |= (new_mem->start << PAGE_SHIFT) + surf->tbo.bdev->man[new_mem->mem_type].gpu_offset;
521 	} else
522 		cmd->u.surface_create.data = qxl_bo_physical_address(qdev, surf, 0);
523 	cmd->surface_id = surf->surface_id;
524 	qxl_release_unmap(qdev, release, &cmd->release_info);
525 
526 	surf->surf_create = release;
527 
528 	/* no need to add a release to the fence for this surface bo,
529 	   since it is only released when we ask to destroy the surface
530 	   and it would never signal otherwise */
531 	qxl_push_command_ring_release(qdev, release, QXL_CMD_SURFACE, false);
532 	qxl_release_fence_buffer_objects(release);
533 
534 	surf->hw_surf_alloc = true;
535 	spin_lock(&qdev->surf_id_idr_lock);
536 	idr_replace(&qdev->surf_id_idr, surf, surf->surface_id);
537 	spin_unlock(&qdev->surf_id_idr_lock);
538 	return 0;
539 }
540 
541 int qxl_hw_surface_dealloc(struct qxl_device *qdev,
542 			   struct qxl_bo *surf)
543 {
544 	struct qxl_surface_cmd *cmd;
545 	struct qxl_release *release;
546 	int ret;
547 	int id;
548 
549 	if (!surf->hw_surf_alloc)
550 		return 0;
551 
552 	ret = qxl_alloc_surface_release_reserved(qdev, QXL_SURFACE_CMD_DESTROY,
553 						 surf->surf_create,
554 						 &release);
555 	if (ret)
556 		return ret;
557 
558 	surf->surf_create = NULL;
559 	/* remove the surface from the idr, but not the surface id yet */
560 	spin_lock(&qdev->surf_id_idr_lock);
561 	idr_replace(&qdev->surf_id_idr, NULL, surf->surface_id);
562 	spin_unlock(&qdev->surf_id_idr_lock);
563 	surf->hw_surf_alloc = false;
564 
565 	id = surf->surface_id;
566 	surf->surface_id = 0;
567 
568 	release->surface_release_id = id;
569 	cmd = (struct qxl_surface_cmd *)qxl_release_map(qdev, release);
570 	cmd->type = QXL_SURFACE_CMD_DESTROY;
571 	cmd->surface_id = id;
572 	qxl_release_unmap(qdev, release, &cmd->release_info);
573 
574 	qxl_push_command_ring_release(qdev, release, QXL_CMD_SURFACE, false);
575 
576 	qxl_release_fence_buffer_objects(release);
577 
578 	return 0;
579 }
580 
581 int qxl_update_surface(struct qxl_device *qdev, struct qxl_bo *surf)
582 {
583 	struct qxl_rect rect;
584 	int ret;
585 
586 	/* if we are evicting, we need to make sure the surface is up
587 	   to date */
588 	rect.left = 0;
589 	rect.right = surf->surf.width;
590 	rect.top = 0;
591 	rect.bottom = surf->surf.height;
592 retry:
593 	ret = qxl_io_update_area(qdev, surf, &rect);
594 	if (ret == -ERESTARTSYS)
595 		goto retry;
596 	return ret;
597 }
598 
599 static void qxl_surface_evict_locked(struct qxl_device *qdev, struct qxl_bo *surf, bool do_update_area)
600 {
601 	/* no need to update area if we are just freeing the surface normally */
602 	if (do_update_area)
603 		qxl_update_surface(qdev, surf);
604 
605 	/* nuke the surface id at the hw */
606 	qxl_hw_surface_dealloc(qdev, surf);
607 }
608 
609 void qxl_surface_evict(struct qxl_device *qdev, struct qxl_bo *surf, bool do_update_area)
610 {
611 	mutex_lock(&qdev->surf_evict_mutex);
612 	qxl_surface_evict_locked(qdev, surf, do_update_area);
613 	mutex_unlock(&qdev->surf_evict_mutex);
614 }
615 
616 static int qxl_reap_surf(struct qxl_device *qdev, struct qxl_bo *surf, bool stall)
617 {
618 	int ret;
619 
620 	ret = qxl_bo_reserve(surf, false);
621 	if (ret)
622 		return ret;
623 
624 	if (stall)
625 		mutex_unlock(&qdev->surf_evict_mutex);
626 
627 	ret = ttm_bo_wait(&surf->tbo, true, !stall);
628 
629 	if (stall)
630 		mutex_lock(&qdev->surf_evict_mutex);
631 	if (ret) {
632 		qxl_bo_unreserve(surf);
633 		return ret;
634 	}
635 
636 	qxl_surface_evict_locked(qdev, surf, true);
637 	qxl_bo_unreserve(surf);
638 	return 0;
639 }
640 
641 static int qxl_reap_surface_id(struct qxl_device *qdev, int max_to_reap)
642 {
643 	int num_reaped = 0;
644 	int i, ret;
645 	bool stall = false;
646 	int start = 0;
647 
648 	mutex_lock(&qdev->surf_evict_mutex);
649 again:
650 
651 	spin_lock(&qdev->surf_id_idr_lock);
652 	start = qdev->last_alloced_surf_id + 1;
653 	spin_unlock(&qdev->surf_id_idr_lock);
654 
655 	for (i = start; i < start + qdev->rom->n_surfaces; i++) {
656 		void *objptr;
657 		int surfid = i % qdev->rom->n_surfaces;
658 
659 		/* this avoids the case where the objects is in the
660 		   idr but has been evicted half way - its makes
661 		   the idr lookup atomic with the eviction */
662 		spin_lock(&qdev->surf_id_idr_lock);
663 		objptr = idr_find(&qdev->surf_id_idr, surfid);
664 		spin_unlock(&qdev->surf_id_idr_lock);
665 
666 		if (!objptr)
667 			continue;
668 
669 		ret = qxl_reap_surf(qdev, objptr, stall);
670 		if (ret == 0)
671 			num_reaped++;
672 		if (num_reaped >= max_to_reap)
673 			break;
674 	}
675 	if (num_reaped == 0 && stall == false) {
676 		stall = true;
677 		goto again;
678 	}
679 
680 	mutex_unlock(&qdev->surf_evict_mutex);
681 	if (num_reaped) {
682 		usleep_range(500, 1000);
683 		qxl_queue_garbage_collect(qdev, true);
684 	}
685 
686 	return 0;
687 }
688