linux-core/drm_lock.c

   1 /* lock.c -- IOCTLs for locking -*- linux-c -*-
   2  * Created: Tue Feb  2 08:37:54 1999 by faith@valinux.com
   3  *
   4  * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
   5  * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
   6  * All Rights Reserved.
   7  *
   8  * Permission is hereby granted, free of charge, to any person obtaining a
   9  * copy of this software and associated documentation files (the "Software"),
  10  * to deal in the Software without restriction, including without limitation
  11  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  12  * and/or sell copies of the Software, and to permit persons to whom the
  13  * Software is furnished to do so, subject to the following conditions:
  14  *
  15  * The above copyright notice and this permission notice (including the next
  16  * paragraph) shall be included in all copies or substantial portions of the
  17  * 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 NONINFRINGEMENT.  IN NO EVENT SHALL
  22  * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  23  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  24  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  25  * OTHER DEALINGS IN THE SOFTWARE.
  26  *
  27  * Authors:
  28  *    Rickard E. (Rik) Faith <faith@valinux.com>
  29  *    Gareth Hughes <gareth@valinux.com>
  30  */
  31
  32 #define __NO_VERSION__
  33 #include "drmP.h"
  34
  35 int DRM(block)(struct inode *inode, struct file *filp, unsigned int cmd,
  36                unsigned long arg)
  37 {
  38         DRM_DEBUG("\n");
  39         return 0;
  40 }
  41
  42 int DRM(unblock)(struct inode *inode, struct file *filp, unsigned int cmd,
  43                  unsigned long arg)
  44 {
  45         DRM_DEBUG("\n");
  46         return 0;
  47 }
  48
  49 int DRM(lock_take)(__volatile__ unsigned int *lock, unsigned int context)
  50 {
  51         unsigned int old, new, prev;
  52
  53         do {
  54                 old = *lock;
  55                 if (old & _DRM_LOCK_HELD) new = old | _DRM_LOCK_CONT;
  56                 else                      new = context | _DRM_LOCK_HELD;
  57                 prev = cmpxchg(lock, old, new);
  58         } while (prev != old);
  59         if (_DRM_LOCKING_CONTEXT(old) == context) {
  60                 if (old & _DRM_LOCK_HELD) {
  61                         if (context != DRM_KERNEL_CONTEXT) {
  62                                 DRM_ERROR("%d holds heavyweight lock\n",
  63                                           context);
  64                         }
  65                         return 0;
  66                 }
  67         }
  68         if (new == (context | _DRM_LOCK_HELD)) {
  69                                 /* Have lock */
  70                 return 1;
  71         }
  72         return 0;
  73 }
  74
  75 /* This takes a lock forcibly and hands it to context.  Should ONLY be used
  76    inside *_unlock to give lock to kernel before calling *_dma_schedule. */
  77 int DRM(lock_transfer)(drm_device_t *dev,
  78                        __volatile__ unsigned int *lock, unsigned int context)
  79 {
  80         unsigned int old, new, prev;
  81
  82         dev->lock.pid = 0;
  83         do {
  84                 old  = *lock;
  85                 new  = context | _DRM_LOCK_HELD;
  86                 prev = cmpxchg(lock, old, new);
  87         } while (prev != old);
  88         return 1;
  89 }
  90
  91 int DRM(lock_free)(drm_device_t *dev,
  92                    __volatile__ unsigned int *lock, unsigned int context)
  93 {
  94         unsigned int old, new, prev;
  95         pid_t        pid = dev->lock.pid;
  96
  97         dev->lock.pid = 0;
  98         do {
  99                 old  = *lock;
 100                 new  = 0;
 101                 prev = cmpxchg(lock, old, new);
 102         } while (prev != old);
 103         if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) {
 104                 DRM_ERROR("%d freed heavyweight lock held by %d (pid %d)\n",
 105                           context,
 106                           _DRM_LOCKING_CONTEXT(old),
 107                           pid);
 108                 return 1;
 109         }
 110         wake_up_interruptible(&dev->lock.lock_queue);
 111         return 0;
 112 }
 113
 114 static int DRM(flush_queue)(drm_device_t *dev, int context)
 115 {
 116         DECLARE_WAITQUEUE(entry, current);
 117         int               ret   = 0;
 118         drm_queue_t       *q    = dev->queuelist[context];
 119
 120         DRM_DEBUG("\n");
 121
 122         atomic_inc(&q->use_count);
 123         if (atomic_read(&q->use_count) > 1) {
 124                 atomic_inc(&q->block_write);
 125                 add_wait_queue(&q->flush_queue, &entry);
 126                 atomic_inc(&q->block_count);
 127                 for (;;) {
 128                         current->state = TASK_INTERRUPTIBLE;
 129                         if (!DRM_BUFCOUNT(&q->waitlist)) break;
 130                         schedule();
 131                         if (signal_pending(current)) {
 132                                 ret = -EINTR; /* Can't restart */
 133                                 break;
 134                         }
 135                 }
 136                 atomic_dec(&q->block_count);
 137                 current->state = TASK_RUNNING;
 138                 remove_wait_queue(&q->flush_queue, &entry);
 139         }
 140         atomic_dec(&q->use_count);
 141
 142                                 /* NOTE: block_write is still incremented!
 143                                    Use drm_flush_unlock_queue to decrement. */
 144         return ret;
 145 }
 146
 147 static int DRM(flush_unblock_queue)(drm_device_t *dev, int context)
 148 {
 149         drm_queue_t       *q    = dev->queuelist[context];
 150
 151         DRM_DEBUG("\n");
 152
 153         atomic_inc(&q->use_count);
 154         if (atomic_read(&q->use_count) > 1) {
 155                 if (atomic_read(&q->block_write)) {
 156                         atomic_dec(&q->block_write);
 157                         wake_up_interruptible(&q->write_queue);
 158                 }
 159         }
 160         atomic_dec(&q->use_count);
 161         return 0;
 162 }
 163
 164 int DRM(flush_block_and_flush)(drm_device_t *dev, int context,
 165                                drm_lock_flags_t flags)
 166 {
 167         int ret = 0;
 168         int i;
 169
 170         DRM_DEBUG("\n");
 171
 172         if (flags & _DRM_LOCK_FLUSH) {
 173                 ret = DRM(flush_queue)(dev, DRM_KERNEL_CONTEXT);
 174                 if (!ret) ret = DRM(flush_queue)(dev, context);
 175         }
 176         if (flags & _DRM_LOCK_FLUSH_ALL) {
 177                 for (i = 0; !ret && i < dev->queue_count; i++) {
 178                         ret = DRM(flush_queue)(dev, i);
 179                 }
 180         }
 181         return ret;
 182 }
 183
 184 int DRM(flush_unblock)(drm_device_t *dev, int context, drm_lock_flags_t flags)
 185 {
 186         int ret = 0;
 187         int i;
 188
 189         DRM_DEBUG("\n");
 190
 191         if (flags & _DRM_LOCK_FLUSH) {
 192                 ret = DRM(flush_unblock_queue)(dev, DRM_KERNEL_CONTEXT);
 193                 if (!ret) ret = DRM(flush_unblock_queue)(dev, context);
 194         }
 195         if (flags & _DRM_LOCK_FLUSH_ALL) {
 196                 for (i = 0; !ret && i < dev->queue_count; i++) {
 197                         ret = DRM(flush_unblock_queue)(dev, i);
 198                 }
 199         }
 200
 201         return ret;
 202 }
 203
 204 int DRM(finish)(struct inode *inode, struct file *filp, unsigned int cmd,
 205                 unsigned long arg)
 206 {
 207         drm_file_t        *priv   = filp->private_data;
 208         drm_device_t      *dev    = priv->dev;
 209         int               ret     = 0;
 210         drm_lock_t        lock;
 211
 212         DRM_DEBUG("\n");
 213
 214         if (copy_from_user(&lock, (drm_lock_t *)arg, sizeof(lock)))
 215                 return -EFAULT;
 216         ret = DRM(flush_block_and_flush)(dev, lock.context, lock.flags);
 217         DRM(flush_unblock)(dev, lock.context, lock.flags);
 218         return ret;
 219 }
 220
 221 /* If we get here, it means that the process has called DRM_IOCTL_LOCK
 222    without calling DRM_IOCTL_UNLOCK.
 223
 224    If the lock is not held, then let the signal proceed as usual.
 225
 226    If the lock is held, then set the contended flag and keep the signal
 227    blocked.
 228
 229
 230    Return 1 if the signal should be delivered normally.
 231    Return 0 if the signal should be blocked.  */
 232
 233 int DRM(notifier)(void *priv)
 234 {
 235         drm_sigdata_t *s = (drm_sigdata_t *)priv;
 236         unsigned int  old, new, prev;
 237
 238
 239                                 /* Allow signal delivery if lock isn't held */
 240         if (!s->lock || !_DRM_LOCK_IS_HELD(s->lock->lock)
 241             || _DRM_LOCKING_CONTEXT(s->lock->lock) != s->context) return 1;
 242
 243                                 /* Otherwise, set flag to force call to
 244                                    drmUnlock */
 245         do {
 246                 old  = s->lock->lock;
 247                 new  = old | _DRM_LOCK_CONT;
 248                 prev = cmpxchg(&s->lock->lock, old, new);
 249         } while (prev != old);
 250         return 0;
 251 }