drivers/gpu/drm/ttm/ttm_lock.c

   1 /* SPDX-License-Identifier: GPL-2.0 OR MIT */
   2 /**************************************************************************
   3  *
   4  * Copyright (c) 2007-2009 VMware, Inc., Palo Alto, CA., USA
   5  * All Rights Reserved.
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a
   8  * copy of this software and associated documentation files (the
   9  * "Software"), to deal in the Software without restriction, including
  10  * without limitation the rights to use, copy, modify, merge, publish,
  11  * distribute, sub license, and/or sell copies of the Software, and to
  12  * permit persons to whom the Software is furnished to do so, subject to
  13  * the following conditions:
  14  *
  15  * The above copyright notice and this permission notice (including the
  16  * next paragraph) shall be included in all copies or substantial portions
  17  * of the Software.
  18  *
  19  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  20  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  21  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
  22  * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
  23  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  24  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  25  * USE OR OTHER DEALINGS IN THE SOFTWARE.
  26  *
  27  **************************************************************************/
  28 /*
  29  * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
  30  */
  31
  32 #include <drm/ttm/ttm_lock.h>
  33 #include <drm/ttm/ttm_module.h>
  34 #include <linux/atomic.h>
  35 #include <linux/errno.h>
  36 #include <linux/wait.h>
  37 #include <linux/sched/signal.h>
  38 #include <linux/module.h>
  39
  40 #define TTM_WRITE_LOCK_PENDING    (1 << 0)
  41 #define TTM_VT_LOCK_PENDING       (1 << 1)
  42 #define TTM_SUSPEND_LOCK_PENDING  (1 << 2)
  43 #define TTM_VT_LOCK               (1 << 3)
  44 #define TTM_SUSPEND_LOCK          (1 << 4)
  45
  46 void ttm_lock_init(struct ttm_lock *lock)
  47 {
  48         spin_lock_init(&lock->lock);
  49         init_waitqueue_head(&lock->queue);
  50         lock->rw = 0;
  51         lock->flags = 0;
  52         lock->kill_takers = false;
  53         lock->signal = SIGKILL;
  54 }
  55 EXPORT_SYMBOL(ttm_lock_init);
  56
  57 void ttm_read_unlock(struct ttm_lock *lock)
  58 {
  59         spin_lock(&lock->lock);
  60         if (--lock->rw == 0)
  61                 wake_up_all(&lock->queue);
  62         spin_unlock(&lock->lock);
  63 }
  64 EXPORT_SYMBOL(ttm_read_unlock);
  65
  66 static bool __ttm_read_lock(struct ttm_lock *lock)
  67 {
  68         bool locked = false;
  69
  70         spin_lock(&lock->lock);
  71         if (unlikely(lock->kill_takers)) {
  72                 send_sig(lock->signal, current, 0);
  73                 spin_unlock(&lock->lock);
  74                 return false;
  75         }
  76         if (lock->rw >= 0 && lock->flags == 0) {
  77                 ++lock->rw;
  78                 locked = true;
  79         }
  80         spin_unlock(&lock->lock);
  81         return locked;
  82 }
  83
  84 int ttm_read_lock(struct ttm_lock *lock, bool interruptible)
  85 {
  86         int ret = 0;
  87
  88         if (interruptible)
  89                 ret = wait_event_interruptible(lock->queue,
  90                                                __ttm_read_lock(lock));
  91         else
  92                 wait_event(lock->queue, __ttm_read_lock(lock));
  93         return ret;
  94 }
  95 EXPORT_SYMBOL(ttm_read_lock);
  96
  97 static bool __ttm_read_trylock(struct ttm_lock *lock, bool *locked)
  98 {
  99         bool block = true;
 100
 101         *locked = false;
 102
 103         spin_lock(&lock->lock);
 104         if (unlikely(lock->kill_takers)) {
 105                 send_sig(lock->signal, current, 0);
 106                 spin_unlock(&lock->lock);
 107                 return false;
 108         }
 109         if (lock->rw >= 0 && lock->flags == 0) {
 110                 ++lock->rw;
 111                 block = false;
 112                 *locked = true;
 113         } else if (lock->flags == 0) {
 114                 block = false;
 115         }
 116         spin_unlock(&lock->lock);
 117
 118         return !block;
 119 }
 120
 121 int ttm_read_trylock(struct ttm_lock *lock, bool interruptible)
 122 {
 123         int ret = 0;
 124         bool locked;
 125
 126         if (interruptible)
 127                 ret = wait_event_interruptible
 128                         (lock->queue, __ttm_read_trylock(lock, &locked));
 129         else
 130                 wait_event(lock->queue, __ttm_read_trylock(lock, &locked));
 131
 132         if (unlikely(ret != 0)) {
 133                 BUG_ON(locked);
 134                 return ret;
 135         }
 136
 137         return (locked) ? 0 : -EBUSY;
 138 }
 139
 140 void ttm_write_unlock(struct ttm_lock *lock)
 141 {
 142         spin_lock(&lock->lock);
 143         lock->rw = 0;
 144         wake_up_all(&lock->queue);
 145         spin_unlock(&lock->lock);
 146 }
 147 EXPORT_SYMBOL(ttm_write_unlock);
 148
 149 static bool __ttm_write_lock(struct ttm_lock *lock)
 150 {
 151         bool locked = false;
 152
 153         spin_lock(&lock->lock);
 154         if (unlikely(lock->kill_takers)) {
 155                 send_sig(lock->signal, current, 0);
 156                 spin_unlock(&lock->lock);
 157                 return false;
 158         }
 159         if (lock->rw == 0 && ((lock->flags & ~TTM_WRITE_LOCK_PENDING) == 0)) {
 160                 lock->rw = -1;
 161                 lock->flags &= ~TTM_WRITE_LOCK_PENDING;
 162                 locked = true;
 163         } else {
 164                 lock->flags |= TTM_WRITE_LOCK_PENDING;
 165         }
 166         spin_unlock(&lock->lock);
 167         return locked;
 168 }
 169
 170 int ttm_write_lock(struct ttm_lock *lock, bool interruptible)
 171 {
 172         int ret = 0;
 173
 174         if (interruptible) {
 175                 ret = wait_event_interruptible(lock->queue,
 176                                                __ttm_write_lock(lock));
 177                 if (unlikely(ret != 0)) {
 178                         spin_lock(&lock->lock);
 179                         lock->flags &= ~TTM_WRITE_LOCK_PENDING;
 180                         wake_up_all(&lock->queue);
 181                         spin_unlock(&lock->lock);
 182                 }
 183         } else
 184                 wait_event(lock->queue, __ttm_write_lock(lock));
 185
 186         return ret;
 187 }
 188 EXPORT_SYMBOL(ttm_write_lock);
 189
 190 static int __ttm_vt_unlock(struct ttm_lock *lock)
 191 {
 192         int ret = 0;
 193
 194         spin_lock(&lock->lock);
 195         if (unlikely(!(lock->flags & TTM_VT_LOCK)))
 196                 ret = -EINVAL;
 197         lock->flags &= ~TTM_VT_LOCK;
 198         wake_up_all(&lock->queue);
 199         spin_unlock(&lock->lock);
 200
 201         return ret;
 202 }
 203
 204 static void ttm_vt_lock_remove(struct ttm_base_object **p_base)
 205 {
 206         struct ttm_base_object *base = *p_base;
 207         struct ttm_lock *lock = container_of(base, struct ttm_lock, base);
 208         int ret;
 209
 210         *p_base = NULL;
 211         ret = __ttm_vt_unlock(lock);
 212         BUG_ON(ret != 0);
 213 }
 214
 215 static bool __ttm_vt_lock(struct ttm_lock *lock)
 216 {
 217         bool locked = false;
 218
 219         spin_lock(&lock->lock);
 220         if (lock->rw == 0) {
 221                 lock->flags &= ~TTM_VT_LOCK_PENDING;
 222                 lock->flags |= TTM_VT_LOCK;
 223                 locked = true;
 224         } else {
 225                 lock->flags |= TTM_VT_LOCK_PENDING;
 226         }
 227         spin_unlock(&lock->lock);
 228         return locked;
 229 }
 230
 231 int ttm_vt_lock(struct ttm_lock *lock,
 232                 bool interruptible,
 233                 struct ttm_object_file *tfile)
 234 {
 235         int ret = 0;
 236
 237         if (interruptible) {
 238                 ret = wait_event_interruptible(lock->queue,
 239                                                __ttm_vt_lock(lock));
 240                 if (unlikely(ret != 0)) {
 241                         spin_lock(&lock->lock);
 242                         lock->flags &= ~TTM_VT_LOCK_PENDING;
 243                         wake_up_all(&lock->queue);
 244                         spin_unlock(&lock->lock);
 245                         return ret;
 246                 }
 247         } else
 248                 wait_event(lock->queue, __ttm_vt_lock(lock));
 249
 250         /*
 251          * Add a base-object, the destructor of which will
 252          * make sure the lock is released if the client dies
 253          * while holding it.
 254          */
 255
 256         ret = ttm_base_object_init(tfile, &lock->base, false,
 257                                    ttm_lock_type, &ttm_vt_lock_remove, NULL);
 258         if (ret)
 259                 (void)__ttm_vt_unlock(lock);
 260         else
 261                 lock->vt_holder = tfile;
 262
 263         return ret;
 264 }
 265 EXPORT_SYMBOL(ttm_vt_lock);
 266
 267 int ttm_vt_unlock(struct ttm_lock *lock)
 268 {
 269         return ttm_ref_object_base_unref(lock->vt_holder,
 270                                          lock->base.hash.key, TTM_REF_USAGE);
 271 }
 272 EXPORT_SYMBOL(ttm_vt_unlock);
 273
 274 void ttm_suspend_unlock(struct ttm_lock *lock)
 275 {
 276         spin_lock(&lock->lock);
 277         lock->flags &= ~TTM_SUSPEND_LOCK;
 278         wake_up_all(&lock->queue);
 279         spin_unlock(&lock->lock);
 280 }
 281 EXPORT_SYMBOL(ttm_suspend_unlock);
 282
 283 static bool __ttm_suspend_lock(struct ttm_lock *lock)
 284 {
 285         bool locked = false;
 286
 287         spin_lock(&lock->lock);
 288         if (lock->rw == 0) {
 289                 lock->flags &= ~TTM_SUSPEND_LOCK_PENDING;
 290                 lock->flags |= TTM_SUSPEND_LOCK;
 291                 locked = true;
 292         } else {
 293                 lock->flags |= TTM_SUSPEND_LOCK_PENDING;
 294         }
 295         spin_unlock(&lock->lock);
 296         return locked;
 297 }
 298
 299 void ttm_suspend_lock(struct ttm_lock *lock)
 300 {
 301         wait_event(lock->queue, __ttm_suspend_lock(lock));
 302 }
 303 EXPORT_SYMBOL(ttm_suspend_lock);