linux/drivers/gpu/drm/ttm/ttm_lock.c
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   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,
  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 * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
  29 */
  30
  31#include "ttm/ttm_lock.h"
  32#include "ttm/ttm_module.h"
  33#include <linux/atomic.h>
  34#include <linux/errno.h>
  35#include <linux/wait.h>
  36#include <linux/sched.h>
  37#include <linux/module.h>
  38
  39#define TTM_WRITE_LOCK_PENDING    (1 << 0)
  40#define TTM_VT_LOCK_PENDING       (1 << 1)
  41#define TTM_SUSPEND_LOCK_PENDING  (1 << 2)
  42#define TTM_VT_LOCK               (1 << 3)
  43#define TTM_SUSPEND_LOCK          (1 << 4)
  44
  45void ttm_lock_init(struct ttm_lock *lock)
  46{
  47        spin_lock_init(&lock->lock);
  48        init_waitqueue_head(&lock->queue);
  49        lock->rw = 0;
  50        lock->flags = 0;
  51        lock->kill_takers = false;
  52        lock->signal = SIGKILL;
  53}
  54EXPORT_SYMBOL(ttm_lock_init);
  55
  56void ttm_read_unlock(struct ttm_lock *lock)
  57{
  58        spin_lock(&lock->lock);
  59        if (--lock->rw == 0)
  60                wake_up_all(&lock->queue);
  61        spin_unlock(&lock->lock);
  62}
  63EXPORT_SYMBOL(ttm_read_unlock);
  64
  65static bool __ttm_read_lock(struct ttm_lock *lock)
  66{
  67        bool locked = false;
  68
  69        spin_lock(&lock->lock);
  70        if (unlikely(lock->kill_takers)) {
  71                send_sig(lock->signal, current, 0);
  72                spin_unlock(&lock->lock);
  73                return false;
  74        }
  75        if (lock->rw >= 0 && lock->flags == 0) {
  76                ++lock->rw;
  77                locked = true;
  78        }
  79        spin_unlock(&lock->lock);
  80        return locked;
  81}
  82
  83int ttm_read_lock(struct ttm_lock *lock, bool interruptible)
  84{
  85        int ret = 0;
  86
  87        if (interruptible)
  88                ret = wait_event_interruptible(lock->queue,
  89                                               __ttm_read_lock(lock));
  90        else
  91                wait_event(lock->queue, __ttm_read_lock(lock));
  92        return ret;
  93}
  94EXPORT_SYMBOL(ttm_read_lock);
  95
  96static bool __ttm_read_trylock(struct ttm_lock *lock, bool *locked)
  97{
  98        bool block = true;
  99
 100        *locked = false;
 101
 102        spin_lock(&lock->lock);
 103        if (unlikely(lock->kill_takers)) {
 104                send_sig(lock->signal, current, 0);
 105                spin_unlock(&lock->lock);
 106                return false;
 107        }
 108        if (lock->rw >= 0 && lock->flags == 0) {
 109                ++lock->rw;
 110                block = false;
 111                *locked = true;
 112        } else if (lock->flags == 0) {
 113                block = false;
 114        }
 115        spin_unlock(&lock->lock);
 116
 117        return !block;
 118}
 119
 120int ttm_read_trylock(struct ttm_lock *lock, bool interruptible)
 121{
 122        int ret = 0;
 123        bool locked;
 124
 125        if (interruptible)
 126                ret = wait_event_interruptible
 127                        (lock->queue, __ttm_read_trylock(lock, &locked));
 128        else
 129                wait_event(lock->queue, __ttm_read_trylock(lock, &locked));
 130
 131        if (unlikely(ret != 0)) {
 132                BUG_ON(locked);
 133                return ret;
 134        }
 135
 136        return (locked) ? 0 : -EBUSY;
 137}
 138
 139void ttm_write_unlock(struct ttm_lock *lock)
 140{
 141        spin_lock(&lock->lock);
 142        lock->rw = 0;
 143        wake_up_all(&lock->queue);
 144        spin_unlock(&lock->lock);
 145}
 146EXPORT_SYMBOL(ttm_write_unlock);
 147
 148static bool __ttm_write_lock(struct ttm_lock *lock)
 149{
 150        bool locked = false;
 151
 152        spin_lock(&lock->lock);
 153        if (unlikely(lock->kill_takers)) {
 154                send_sig(lock->signal, current, 0);
 155                spin_unlock(&lock->lock);
 156                return false;
 157        }
 158        if (lock->rw == 0 && ((lock->flags & ~TTM_WRITE_LOCK_PENDING) == 0)) {
 159                lock->rw = -1;
 160                lock->flags &= ~TTM_WRITE_LOCK_PENDING;
 161                locked = true;
 162        } else {
 163                lock->flags |= TTM_WRITE_LOCK_PENDING;
 164        }
 165        spin_unlock(&lock->lock);
 166        return locked;
 167}
 168
 169int ttm_write_lock(struct ttm_lock *lock, bool interruptible)
 170{
 171        int ret = 0;
 172
 173        if (interruptible) {
 174                ret = wait_event_interruptible(lock->queue,
 175                                               __ttm_write_lock(lock));
 176                if (unlikely(ret != 0)) {
 177                        spin_lock(&lock->lock);
 178                        lock->flags &= ~TTM_WRITE_LOCK_PENDING;
 179                        wake_up_all(&lock->queue);
 180                        spin_unlock(&lock->lock);
 181                }
 182        } else
 183                wait_event(lock->queue, __ttm_read_lock(lock));
 184
 185        return ret;
 186}
 187EXPORT_SYMBOL(ttm_write_lock);
 188
 189void ttm_write_lock_downgrade(struct ttm_lock *lock)
 190{
 191        spin_lock(&lock->lock);
 192        lock->rw = 1;
 193        wake_up_all(&lock->queue);
 194        spin_unlock(&lock->lock);
 195}
 196
 197static int __ttm_vt_unlock(struct ttm_lock *lock)
 198{
 199        int ret = 0;
 200
 201        spin_lock(&lock->lock);
 202        if (unlikely(!(lock->flags & TTM_VT_LOCK)))
 203                ret = -EINVAL;
 204        lock->flags &= ~TTM_VT_LOCK;
 205        wake_up_all(&lock->queue);
 206        spin_unlock(&lock->lock);
 207
 208        return ret;
 209}
 210
 211static void ttm_vt_lock_remove(struct ttm_base_object **p_base)
 212{
 213        struct ttm_base_object *base = *p_base;
 214        struct ttm_lock *lock = container_of(base, struct ttm_lock, base);
 215        int ret;
 216
 217        *p_base = NULL;
 218        ret = __ttm_vt_unlock(lock);
 219        BUG_ON(ret != 0);
 220}
 221
 222static bool __ttm_vt_lock(struct ttm_lock *lock)
 223{
 224        bool locked = false;
 225
 226        spin_lock(&lock->lock);
 227        if (lock->rw == 0) {
 228                lock->flags &= ~TTM_VT_LOCK_PENDING;
 229                lock->flags |= TTM_VT_LOCK;
 230                locked = true;
 231        } else {
 232                lock->flags |= TTM_VT_LOCK_PENDING;
 233        }
 234        spin_unlock(&lock->lock);
 235        return locked;
 236}
 237
 238int ttm_vt_lock(struct ttm_lock *lock,
 239                bool interruptible,
 240                struct ttm_object_file *tfile)
 241{
 242        int ret = 0;
 243
 244        if (interruptible) {
 245                ret = wait_event_interruptible(lock->queue,
 246                                               __ttm_vt_lock(lock));
 247                if (unlikely(ret != 0)) {
 248                        spin_lock(&lock->lock);
 249                        lock->flags &= ~TTM_VT_LOCK_PENDING;
 250                        wake_up_all(&lock->queue);
 251                        spin_unlock(&lock->lock);
 252                        return ret;
 253                }
 254        } else
 255                wait_event(lock->queue, __ttm_vt_lock(lock));
 256
 257        /*
 258         * Add a base-object, the destructor of which will
 259         * make sure the lock is released if the client dies
 260         * while holding it.
 261         */
 262
 263        ret = ttm_base_object_init(tfile, &lock->base, false,
 264                                   ttm_lock_type, &ttm_vt_lock_remove, NULL);
 265        if (ret)
 266                (void)__ttm_vt_unlock(lock);
 267        else
 268                lock->vt_holder = tfile;
 269
 270        return ret;
 271}
 272EXPORT_SYMBOL(ttm_vt_lock);
 273
 274int ttm_vt_unlock(struct ttm_lock *lock)
 275{
 276        return ttm_ref_object_base_unref(lock->vt_holder,
 277                                         lock->base.hash.key, TTM_REF_USAGE);
 278}
 279EXPORT_SYMBOL(ttm_vt_unlock);
 280
 281void ttm_suspend_unlock(struct ttm_lock *lock)
 282{
 283        spin_lock(&lock->lock);
 284        lock->flags &= ~TTM_SUSPEND_LOCK;
 285        wake_up_all(&lock->queue);
 286        spin_unlock(&lock->lock);
 287}
 288EXPORT_SYMBOL(ttm_suspend_unlock);
 289
 290static bool __ttm_suspend_lock(struct ttm_lock *lock)
 291{
 292        bool locked = false;
 293
 294        spin_lock(&lock->lock);
 295        if (lock->rw == 0) {
 296                lock->flags &= ~TTM_SUSPEND_LOCK_PENDING;
 297                lock->flags |= TTM_SUSPEND_LOCK;
 298                locked = true;
 299        } else {
 300                lock->flags |= TTM_SUSPEND_LOCK_PENDING;
 301        }
 302        spin_unlock(&lock->lock);
 303        return locked;
 304}
 305
 306void ttm_suspend_lock(struct ttm_lock *lock)
 307{
 308        wait_event(lock->queue, __ttm_suspend_lock(lock));
 309}
 310EXPORT_SYMBOL(ttm_suspend_lock);
 311