xref: /freebsd/sys/dev/drm2/ttm/ttm_lock.c (revision bc96366c864c07ef352edb92017357917c75b36c) 
1 /**************************************************************************
2  *
3  * Copyright (c) 2007-2009 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,
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23  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
24  * USE OR OTHER DEALINGS IN THE SOFTWARE.
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26  **************************************************************************/
27 /*
28  * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
29  */
30 /*
31  * Copyright (c) 2013 The FreeBSD Foundation
32  * All rights reserved.
33  *
34  * Portions of this software were developed by Konstantin Belousov
35  * <kib@FreeBSD.org> under sponsorship from the FreeBSD Foundation.
36  */
37 
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
40 
41 #include <dev/drm2/ttm/ttm_lock.h>
42 #include <dev/drm2/ttm/ttm_module.h>
43 
44 #define TTM_WRITE_LOCK_PENDING    (1 << 0)
45 #define TTM_VT_LOCK_PENDING       (1 << 1)
46 #define TTM_SUSPEND_LOCK_PENDING  (1 << 2)
47 #define TTM_VT_LOCK               (1 << 3)
48 #define TTM_SUSPEND_LOCK          (1 << 4)
49 
50 void ttm_lock_init(struct ttm_lock *lock)
51 {
52 	mtx_init(&lock->lock, "ttmlk", NULL, MTX_DEF);
53 	lock->rw = 0;
54 	lock->flags = 0;
55 	lock->kill_takers = false;
56 	lock->signal = SIGKILL;
57 }
58 
59 static void
60 ttm_lock_send_sig(int signo)
61 {
62 	struct proc *p;
63 
64 	p = curproc;	/* XXXKIB curthread ? */
65 	PROC_LOCK(p);
66 	kern_psignal(p, signo);
67 	PROC_UNLOCK(p);
68 }
69 
70 void ttm_read_unlock(struct ttm_lock *lock)
71 {
72 	mtx_lock(&lock->lock);
73 	if (--lock->rw == 0)
74 		wakeup(lock);
75 	mtx_unlock(&lock->lock);
76 }
77 
78 static bool __ttm_read_lock(struct ttm_lock *lock)
79 {
80 	bool locked = false;
81 
82 	if (unlikely(lock->kill_takers)) {
83 		ttm_lock_send_sig(lock->signal);
84 		return false;
85 	}
86 	if (lock->rw >= 0 && lock->flags == 0) {
87 		++lock->rw;
88 		locked = true;
89 	}
90 	return locked;
91 }
92 
93 int
94 ttm_read_lock(struct ttm_lock *lock, bool interruptible)
95 {
96 	const char *wmsg;
97 	int flags, ret;
98 
99 	ret = 0;
100 	if (interruptible) {
101 		flags = PCATCH;
102 		wmsg = "ttmri";
103 	} else {
104 		flags = 0;
105 		wmsg = "ttmr";
106 	}
107 	mtx_lock(&lock->lock);
108 	while (!__ttm_read_lock(lock)) {
109 		ret = msleep(lock, &lock->lock, flags, wmsg, 0);
110 		if (ret == EINTR)
111 			ret = ERESTARTSYS;
112 		if (ret != 0)
113 			break;
114 	}
115 	return (-ret);
116 }
117 
118 static bool __ttm_read_trylock(struct ttm_lock *lock, bool *locked)
119 {
120 	bool block = true;
121 
122 	*locked = false;
123 
124 	if (unlikely(lock->kill_takers)) {
125 		ttm_lock_send_sig(lock->signal);
126 		return false;
127 	}
128 	if (lock->rw >= 0 && lock->flags == 0) {
129 		++lock->rw;
130 		block = false;
131 		*locked = true;
132 	} else if (lock->flags == 0) {
133 		block = false;
134 	}
135 
136 	return !block;
137 }
138 
139 int ttm_read_trylock(struct ttm_lock *lock, bool interruptible)
140 {
141 	const char *wmsg;
142 	int flags, ret;
143 	bool locked;
144 
145 	ret = 0;
146 	if (interruptible) {
147 		flags = PCATCH;
148 		wmsg = "ttmrti";
149 	} else {
150 		flags = 0;
151 		wmsg = "ttmrt";
152 	}
153 	mtx_lock(&lock->lock);
154 	while (!__ttm_read_trylock(lock, &locked)) {
155 		ret = msleep(lock, &lock->lock, flags, wmsg, 0);
156 		if (ret == EINTR)
157 			ret = ERESTARTSYS;
158 		if (ret != 0)
159 			break;
160 	}
161 	MPASS(!locked || ret == 0);
162 	mtx_unlock(&lock->lock);
163 
164 	return (locked) ? 0 : -EBUSY;
165 }
166 
167 void ttm_write_unlock(struct ttm_lock *lock)
168 {
169 	mtx_lock(&lock->lock);
170 	lock->rw = 0;
171 	wakeup(lock);
172 	mtx_unlock(&lock->lock);
173 }
174 
175 static bool __ttm_write_lock(struct ttm_lock *lock)
176 {
177 	bool locked = false;
178 
179 	if (unlikely(lock->kill_takers)) {
180 		ttm_lock_send_sig(lock->signal);
181 		return false;
182 	}
183 	if (lock->rw == 0 && ((lock->flags & ~TTM_WRITE_LOCK_PENDING) == 0)) {
184 		lock->rw = -1;
185 		lock->flags &= ~TTM_WRITE_LOCK_PENDING;
186 		locked = true;
187 	} else {
188 		lock->flags |= TTM_WRITE_LOCK_PENDING;
189 	}
190 	return locked;
191 }
192 
193 int
194 ttm_write_lock(struct ttm_lock *lock, bool interruptible)
195 {
196 	const char *wmsg;
197 	int flags, ret;
198 
199 	ret = 0;
200 	if (interruptible) {
201 		flags = PCATCH;
202 		wmsg = "ttmwi";
203 	} else {
204 		flags = 0;
205 		wmsg = "ttmw";
206 	}
207 	mtx_lock(&lock->lock);
208 	/* XXXKIB: linux uses __ttm_read_lock for uninterruptible sleeps */
209 	while (!__ttm_write_lock(lock)) {
210 		ret = msleep(lock, &lock->lock, flags, wmsg, 0);
211 		if (ret == EINTR)
212 			ret = ERESTARTSYS;
213 		if (interruptible && ret != 0) {
214 			lock->flags &= ~TTM_WRITE_LOCK_PENDING;
215 			wakeup(lock);
216 			break;
217 		}
218 	}
219 	mtx_unlock(&lock->lock);
220 
221 	return (-ret);
222 }
223 
224 void ttm_write_lock_downgrade(struct ttm_lock *lock)
225 {
226 	mtx_lock(&lock->lock);
227 	lock->rw = 1;
228 	wakeup(lock);
229 	mtx_unlock(&lock->lock);
230 }
231 
232 static int __ttm_vt_unlock(struct ttm_lock *lock)
233 {
234 	int ret = 0;
235 
236 	mtx_lock(&lock->lock);
237 	if (unlikely(!(lock->flags & TTM_VT_LOCK)))
238 		ret = -EINVAL;
239 	lock->flags &= ~TTM_VT_LOCK;
240 	wakeup(lock);
241 	mtx_unlock(&lock->lock);
242 
243 	return ret;
244 }
245 
246 static void ttm_vt_lock_remove(struct ttm_base_object **p_base)
247 {
248 	struct ttm_base_object *base = *p_base;
249 	struct ttm_lock *lock = container_of(base, struct ttm_lock, base);
250 	int ret;
251 
252 	*p_base = NULL;
253 	ret = __ttm_vt_unlock(lock);
254 	MPASS(ret == 0);
255 }
256 
257 static bool __ttm_vt_lock(struct ttm_lock *lock)
258 {
259 	bool locked = false;
260 
261 	if (lock->rw == 0) {
262 		lock->flags &= ~TTM_VT_LOCK_PENDING;
263 		lock->flags |= TTM_VT_LOCK;
264 		locked = true;
265 	} else {
266 		lock->flags |= TTM_VT_LOCK_PENDING;
267 	}
268 	return locked;
269 }
270 
271 int ttm_vt_lock(struct ttm_lock *lock,
272 		bool interruptible,
273 		struct ttm_object_file *tfile)
274 {
275 	const char *wmsg;
276 	int flags, ret;
277 
278 	ret = 0;
279 	if (interruptible) {
280 		flags = PCATCH;
281 		wmsg = "ttmwi";
282 	} else {
283 		flags = 0;
284 		wmsg = "ttmw";
285 	}
286 	mtx_lock(&lock->lock);
287 	while (!__ttm_vt_lock(lock)) {
288 		ret = msleep(lock, &lock->lock, flags, wmsg, 0);
289 		if (ret == EINTR)
290 			ret = ERESTARTSYS;
291 		if (interruptible && ret != 0) {
292 			lock->flags &= ~TTM_VT_LOCK_PENDING;
293 			wakeup(lock);
294 			break;
295 		}
296 	}
297 
298 	/*
299 	 * Add a base-object, the destructor of which will
300 	 * make sure the lock is released if the client dies
301 	 * while holding it.
302 	 */
303 
304 	ret = ttm_base_object_init(tfile, &lock->base, false,
305 				   ttm_lock_type, &ttm_vt_lock_remove, NULL);
306 	if (ret)
307 		(void)__ttm_vt_unlock(lock);
308 	else
309 		lock->vt_holder = tfile;
310 
311 	return (-ret);
312 }
313 
314 int ttm_vt_unlock(struct ttm_lock *lock)
315 {
316 	return ttm_ref_object_base_unref(lock->vt_holder,
317 					 lock->base.hash.key, TTM_REF_USAGE);
318 }
319 
320 void ttm_suspend_unlock(struct ttm_lock *lock)
321 {
322 	mtx_lock(&lock->lock);
323 	lock->flags &= ~TTM_SUSPEND_LOCK;
324 	wakeup(lock);
325 	mtx_unlock(&lock->lock);
326 }
327 
328 static bool __ttm_suspend_lock(struct ttm_lock *lock)
329 {
330 	bool locked = false;
331 
332 	if (lock->rw == 0) {
333 		lock->flags &= ~TTM_SUSPEND_LOCK_PENDING;
334 		lock->flags |= TTM_SUSPEND_LOCK;
335 		locked = true;
336 	} else {
337 		lock->flags |= TTM_SUSPEND_LOCK_PENDING;
338 	}
339 	return locked;
340 }
341 
342 void ttm_suspend_lock(struct ttm_lock *lock)
343 {
344 	mtx_lock(&lock->lock);
345 	while (!__ttm_suspend_lock(lock))
346 		msleep(lock, &lock->lock, 0, "ttms", 0);
347 	mtx_unlock(&lock->lock);
348 }
349