1 /**************************************************************************
2  *
3  * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
4  * All Rights Reserved.
5  *
6  * Permission is hereby granted, free of charge, to any person obtaining a
7  * copy of this software and associated documentation files (the
8  * "Software"), to deal in the Software without restriction, including
9  * without limitation the rights to use, copy, modify, merge, publish,
10  * distribute, sub license, and/or sell copies of the Software, and to
11  * permit persons to whom the Software is furnished to do so, subject to
12  * the following conditions:
13  *
14  * The above copyright notice and this permission notice (including the
15  * next paragraph) shall be included in all copies or substantial portions
16  * of the Software.
17  *
18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
21  * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
22  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
23  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
24  * USE OR OTHER DEALINGS IN THE SOFTWARE.
25  *
26  **************************************************************************/
27 
28 #include <drm/ttm/ttm_execbuf_util.h>
29 #include <drm/ttm/ttm_bo_driver.h>
30 #include <drm/ttm/ttm_placement.h>
31 #include <linux/wait.h>
32 #include <linux/sched.h>
33 #include <linux/module.h>
34 
35 static void ttm_eu_backoff_reservation_reverse(struct list_head *list,
36 					      struct ttm_validate_buffer *entry)
37 {
38 	list_for_each_entry_continue_reverse(entry, list, head) {
39 		struct ttm_buffer_object *bo = entry->bo;
40 
41 		__ttm_bo_unreserve(bo);
42 	}
43 }
44 
45 static void ttm_eu_del_from_lru_locked(struct list_head *list)
46 {
47 	struct ttm_validate_buffer *entry;
48 
49 	list_for_each_entry(entry, list, head) {
50 		struct ttm_buffer_object *bo = entry->bo;
51 		unsigned put_count = ttm_bo_del_from_lru(bo);
52 
53 		ttm_bo_list_ref_sub(bo, put_count, true);
54 	}
55 }
56 
57 void ttm_eu_backoff_reservation(struct ww_acquire_ctx *ticket,
58 				struct list_head *list)
59 {
60 	struct ttm_validate_buffer *entry;
61 	struct ttm_bo_global *glob;
62 
63 	if (list_empty(list))
64 		return;
65 
66 	entry = list_first_entry(list, struct ttm_validate_buffer, head);
67 	glob = entry->bo->glob;
68 
69 	spin_lock(&glob->lru_lock);
70 	list_for_each_entry(entry, list, head) {
71 		struct ttm_buffer_object *bo = entry->bo;
72 
73 		ttm_bo_add_to_lru(bo);
74 		__ttm_bo_unreserve(bo);
75 	}
76 	spin_unlock(&glob->lru_lock);
77 
78 	if (ticket)
79 		ww_acquire_fini(ticket);
80 }
81 EXPORT_SYMBOL(ttm_eu_backoff_reservation);
82 
83 /*
84  * Reserve buffers for validation.
85  *
86  * If a buffer in the list is marked for CPU access, we back off and
87  * wait for that buffer to become free for GPU access.
88  *
89  * If a buffer is reserved for another validation, the validator with
90  * the highest validation sequence backs off and waits for that buffer
91  * to become unreserved. This prevents deadlocks when validating multiple
92  * buffers in different orders.
93  */
94 
95 int ttm_eu_reserve_buffers(struct ww_acquire_ctx *ticket,
96 			   struct list_head *list, bool intr,
97 			   struct list_head *dups)
98 {
99 	struct ttm_bo_global *glob;
100 	struct ttm_validate_buffer *entry;
101 	int ret;
102 
103 	if (list_empty(list))
104 		return 0;
105 
106 	entry = list_first_entry(list, struct ttm_validate_buffer, head);
107 	glob = entry->bo->glob;
108 
109 	if (ticket)
110 		ww_acquire_init(ticket, &reservation_ww_class);
111 
112 	list_for_each_entry(entry, list, head) {
113 		struct ttm_buffer_object *bo = entry->bo;
114 
115 		ret = __ttm_bo_reserve(bo, intr, (ticket == NULL), true,
116 				       ticket);
117 		if (!ret && unlikely(atomic_read(&bo->cpu_writers) > 0)) {
118 			__ttm_bo_unreserve(bo);
119 
120 			ret = -EBUSY;
121 
122 		} else if (ret == -EALREADY && dups) {
123 			struct ttm_validate_buffer *safe = entry;
124 			entry = list_prev_entry(entry, head);
125 			list_del(&safe->head);
126 			list_add(&safe->head, dups);
127 			continue;
128 		}
129 
130 		if (!ret) {
131 			if (!entry->shared)
132 				continue;
133 
134 			ret = reservation_object_reserve_shared(bo->resv);
135 			if (!ret)
136 				continue;
137 		}
138 
139 		/* uh oh, we lost out, drop every reservation and try
140 		 * to only reserve this buffer, then start over if
141 		 * this succeeds.
142 		 */
143 		ttm_eu_backoff_reservation_reverse(list, entry);
144 
145 		if (ret == -EDEADLK && intr) {
146 			ret = ww_mutex_lock_slow_interruptible(&bo->resv->lock,
147 							       ticket);
148 		} else if (ret == -EDEADLK) {
149 			ww_mutex_lock_slow(&bo->resv->lock, ticket);
150 			ret = 0;
151 		}
152 
153 		if (!ret && entry->shared)
154 			ret = reservation_object_reserve_shared(bo->resv);
155 
156 		if (unlikely(ret != 0)) {
157 			if (ret == -EINTR)
158 				ret = -ERESTARTSYS;
159 			if (ticket) {
160 				ww_acquire_done(ticket);
161 				ww_acquire_fini(ticket);
162 			}
163 			return ret;
164 		}
165 
166 		/* move this item to the front of the list,
167 		 * forces correct iteration of the loop without keeping track
168 		 */
169 		list_del(&entry->head);
170 		list_add(&entry->head, list);
171 	}
172 
173 	if (ticket)
174 		ww_acquire_done(ticket);
175 	spin_lock(&glob->lru_lock);
176 	ttm_eu_del_from_lru_locked(list);
177 	spin_unlock(&glob->lru_lock);
178 	return 0;
179 }
180 EXPORT_SYMBOL(ttm_eu_reserve_buffers);
181 
182 void ttm_eu_fence_buffer_objects(struct ww_acquire_ctx *ticket,
183 				 struct list_head *list, struct fence *fence)
184 {
185 	struct ttm_validate_buffer *entry;
186 	struct ttm_buffer_object *bo;
187 	struct ttm_bo_global *glob;
188 	struct ttm_bo_device *bdev;
189 	struct ttm_bo_driver *driver;
190 
191 	if (list_empty(list))
192 		return;
193 
194 	bo = list_first_entry(list, struct ttm_validate_buffer, head)->bo;
195 	bdev = bo->bdev;
196 	driver = bdev->driver;
197 	glob = bo->glob;
198 
199 	spin_lock(&glob->lru_lock);
200 
201 	list_for_each_entry(entry, list, head) {
202 		bo = entry->bo;
203 		if (entry->shared)
204 			reservation_object_add_shared_fence(bo->resv, fence);
205 		else
206 			reservation_object_add_excl_fence(bo->resv, fence);
207 		ttm_bo_add_to_lru(bo);
208 		__ttm_bo_unreserve(bo);
209 	}
210 	spin_unlock(&glob->lru_lock);
211 	if (ticket)
212 		ww_acquire_fini(ticket);
213 }
214 EXPORT_SYMBOL(ttm_eu_fence_buffer_objects);
215