sys/dev/drm/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 /*-
   5  * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
   6  * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
   7  * All Rights Reserved.
   8  *
   9  * Permission is hereby granted, free of charge, to any person obtaining a
  10  * copy of this software and associated documentation files (the "Software"),
  11  * to deal in the Software without restriction, including without limitation
  12  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  13  * and/or sell copies of the Software, and to permit persons to whom the
  14  * Software is furnished to do so, subject to the following conditions:
  15  *
  16  * The above copyright notice and this permission notice (including the next
  17  * paragraph) shall be included in all copies or substantial portions of the
  18  * Software.
  19  *
  20  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  21  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  23  * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  24  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  25  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  26  * OTHER DEALINGS IN THE SOFTWARE.
  27  *
  28  * Authors:
  29  *    Rickard E. (Rik) Faith <faith@valinux.com>
  30  *    Gareth Hughes <gareth@valinux.com>
  31  *
  32  * $FreeBSD$
  33  */
  34
  35 #include "dev/drm/drmP.h"
  36
  37 int drm_lock_take(__volatile__ unsigned int *lock, unsigned int context)
  38 {
  39         unsigned int old, new;
  40
  41         do {
  42                 old = *lock;
  43                 if (old & _DRM_LOCK_HELD) new = old | _DRM_LOCK_CONT;
  44                 else                      new = context | _DRM_LOCK_HELD;
  45         } while (!atomic_cmpset_int(lock, old, new));
  46
  47         if (_DRM_LOCKING_CONTEXT(old) == context) {
  48                 if (old & _DRM_LOCK_HELD) {
  49                         if (context != DRM_KERNEL_CONTEXT) {
  50                                 DRM_ERROR("%d holds heavyweight lock\n",
  51                                           context);
  52                         }
  53                         return 0;
  54                 }
  55         }
  56         if (new == (context | _DRM_LOCK_HELD)) {
  57                                 /* Have lock */
  58                 return 1;
  59         }
  60         return 0;
  61 }
  62
  63 /* This takes a lock forcibly and hands it to context.  Should ONLY be used
  64    inside *_unlock to give lock to kernel before calling *_dma_schedule. */
  65 int drm_lock_transfer(drm_device_t *dev,
  66                        __volatile__ unsigned int *lock, unsigned int context)
  67 {
  68         unsigned int old, new;
  69
  70         dev->lock.filp = NULL;
  71         do {
  72                 old  = *lock;
  73                 new  = context | _DRM_LOCK_HELD;
  74         } while (!atomic_cmpset_int(lock, old, new));
  75
  76         return 1;
  77 }
  78
  79 int drm_lock_free(drm_device_t *dev,
  80                    __volatile__ unsigned int *lock, unsigned int context)
  81 {
  82         unsigned int old, new;
  83
  84         dev->lock.filp = NULL;
  85         do {
  86                 old  = *lock;
  87                 new  = 0;
  88         } while (!atomic_cmpset_int(lock, old, new));
  89
  90         if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) {
  91                 DRM_ERROR("%d freed heavyweight lock held by %d\n",
  92                           context, _DRM_LOCKING_CONTEXT(old));
  93                 return 1;
  94         }
  95         DRM_WAKEUP_INT((void *)&dev->lock.lock_queue);
  96         return 0;
  97 }
  98
  99 int drm_lock(DRM_IOCTL_ARGS)
 100 {
 101         DRM_DEVICE;
 102         drm_lock_t lock;
 103         int ret = 0;
 104
 105         DRM_COPY_FROM_USER_IOCTL(lock, (drm_lock_t *)data, sizeof(lock));
 106
 107         if (lock.context == DRM_KERNEL_CONTEXT) {
 108                 DRM_ERROR("Process %d using kernel context %d\n",
 109                     DRM_CURRENTPID, lock.context);
 110                 return EINVAL;
 111         }
 112
 113         DRM_DEBUG("%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n",
 114             lock.context, DRM_CURRENTPID, dev->lock.hw_lock->lock, lock.flags);
 115
 116         if (dev->use_dma_queue && lock.context < 0)
 117                 return EINVAL;
 118
 119         DRM_LOCK();
 120         for (;;) {
 121                 if (drm_lock_take(&dev->lock.hw_lock->lock, lock.context)) {
 122                         dev->lock.filp = (void *)(uintptr_t)DRM_CURRENTPID;
 123                         dev->lock.lock_time = jiffies;
 124                         atomic_inc(&dev->counts[_DRM_STAT_LOCKS]);
 125                         break;  /* Got lock */
 126                 }
 127
 128                 /* Contention */
 129 #if defined(__FreeBSD__) && __FreeBSD_version > 500000
 130                 ret = msleep((void *)&dev->lock.lock_queue, &dev->dev_lock,
 131                     PZERO | PCATCH, "drmlk2", 0);
 132 #else
 133                 ret = tsleep((void *)&dev->lock.lock_queue, PZERO | PCATCH,
 134                     "drmlk2", 0);
 135 #endif
 136                 if (ret != 0)
 137                         break;
 138         }
 139         DRM_UNLOCK();
 140         DRM_DEBUG("%d %s\n", lock.context, ret ? "interrupted" : "has lock");
 141
 142         if (ret != 0)
 143                 return ret;
 144
 145         /* XXX: Add signal blocking here */
 146
 147         if (dev->dma_quiescent != NULL && (lock.flags & _DRM_LOCK_QUIESCENT))
 148                 dev->dma_quiescent(dev);
 149
 150         return 0;
 151 }
 152
 153 int drm_unlock(DRM_IOCTL_ARGS)
 154 {
 155         DRM_DEVICE;
 156         drm_lock_t lock;
 157
 158         DRM_COPY_FROM_USER_IOCTL(lock, (drm_lock_t *)data, sizeof(lock));
 159
 160         if (lock.context == DRM_KERNEL_CONTEXT) {
 161                 DRM_ERROR("Process %d using kernel context %d\n",
 162                     DRM_CURRENTPID, lock.context);
 163                 return EINVAL;
 164         }
 165
 166         atomic_inc(&dev->counts[_DRM_STAT_UNLOCKS]);
 167
 168         DRM_LOCK();
 169         drm_lock_transfer(dev, &dev->lock.hw_lock->lock, DRM_KERNEL_CONTEXT);
 170
 171         if (drm_lock_free(dev, &dev->lock.hw_lock->lock, DRM_KERNEL_CONTEXT)) {
 172                 DRM_ERROR("\n");
 173         }
 174         DRM_UNLOCK();
 175
 176         return 0;
 177 }