drm_lock.c

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    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  */
   33 
   34 #include <sys/cdefs.h>
   35 __FBSDID("$FreeBSD: releng/6.4/sys/dev/drm/drm_lock.c 153401 2005-12-14 00:52:59Z anholt $");
   36 
   37 #include "dev/drm/drmP.h"
   38 
   39 int drm_lock_take(__volatile__ unsigned int *lock, unsigned int context)
   40 {
   41         unsigned int old, new;
   42 
   43         do {
   44                 old = *lock;
   45                 if (old & _DRM_LOCK_HELD) new = old | _DRM_LOCK_CONT;
   46                 else                      new = context | _DRM_LOCK_HELD;
   47         } while (!atomic_cmpset_int(lock, old, new));
   48 
   49         if (_DRM_LOCKING_CONTEXT(old) == context) {
   50                 if (old & _DRM_LOCK_HELD) {
   51                         if (context != DRM_KERNEL_CONTEXT) {
   52                                 DRM_ERROR("%d holds heavyweight lock\n",
   53                                           context);
   54                         }
   55                         return 0;
   56                 }
   57         }
   58         if (new == (context | _DRM_LOCK_HELD)) {
   59                                 /* Have lock */
   60                 return 1;
   61         }
   62         return 0;
   63 }
   64 
   65 /* This takes a lock forcibly and hands it to context.  Should ONLY be used
   66    inside *_unlock to give lock to kernel before calling *_dma_schedule. */
   67 int drm_lock_transfer(drm_device_t *dev,
   68                        __volatile__ unsigned int *lock, unsigned int context)
   69 {
   70         unsigned int old, new;
   71 
   72         dev->lock.filp = NULL;
   73         do {
   74                 old  = *lock;
   75                 new  = context | _DRM_LOCK_HELD;
   76         } while (!atomic_cmpset_int(lock, old, new));
   77 
   78         return 1;
   79 }
   80 
   81 int drm_lock_free(drm_device_t *dev,
   82                    __volatile__ unsigned int *lock, unsigned int context)
   83 {
   84         unsigned int old, new;
   85 
   86         dev->lock.filp = NULL;
   87         do {
   88                 old  = *lock;
   89                 new  = 0;
   90         } while (!atomic_cmpset_int(lock, old, new));
   91 
   92         if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) {
   93                 DRM_ERROR("%d freed heavyweight lock held by %d\n",
   94                           context, _DRM_LOCKING_CONTEXT(old));
   95                 return 1;
   96         }
   97         DRM_WAKEUP_INT((void *)&dev->lock.lock_queue);
   98         return 0;
   99 }
  100 
  101 int drm_lock(DRM_IOCTL_ARGS)
  102 {
  103         DRM_DEVICE;
  104         drm_lock_t lock;
  105         int ret = 0;
  106 
  107         DRM_COPY_FROM_USER_IOCTL(lock, (drm_lock_t *)data, sizeof(lock));
  108 
  109         if (lock.context == DRM_KERNEL_CONTEXT) {
  110                 DRM_ERROR("Process %d using kernel context %d\n",
  111                     DRM_CURRENTPID, lock.context);
  112                 return EINVAL;
  113         }
  114 
  115         DRM_DEBUG("%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n",
  116             lock.context, DRM_CURRENTPID, dev->lock.hw_lock->lock, lock.flags);
  117 
  118         if (dev->driver.use_dma_queue && lock.context < 0)
  119                 return EINVAL;
  120 
  121         DRM_LOCK();
  122         for (;;) {
  123                 if (drm_lock_take(&dev->lock.hw_lock->lock, lock.context)) {
  124                         dev->lock.filp = (void *)(uintptr_t)DRM_CURRENTPID;
  125                         dev->lock.lock_time = jiffies;
  126                         atomic_inc(&dev->counts[_DRM_STAT_LOCKS]);
  127                         break;  /* Got lock */
  128                 }
  129 
  130                 /* Contention */
  131 #if defined(__FreeBSD__) && __FreeBSD_version > 500000
  132                 ret = msleep((void *)&dev->lock.lock_queue, &dev->dev_lock,
  133                     PZERO | PCATCH, "drmlk2", 0);
  134 #else
  135                 ret = tsleep((void *)&dev->lock.lock_queue, PZERO | PCATCH,
  136                     "drmlk2", 0);
  137 #endif
  138                 if (ret != 0)
  139                         break;
  140         }
  141         DRM_UNLOCK();
  142         DRM_DEBUG("%d %s\n", lock.context, ret ? "interrupted" : "has lock");
  143 
  144         if (ret != 0)
  145                 return ret;
  146 
  147         /* XXX: Add signal blocking here */
  148 
  149         if (dev->driver.dma_quiescent != NULL &&
  150             (lock.flags & _DRM_LOCK_QUIESCENT))
  151                 dev->driver.dma_quiescent(dev);
  152 
  153         return 0;
  154 }
  155 
  156 int drm_unlock(DRM_IOCTL_ARGS)
  157 {
  158         DRM_DEVICE;
  159         drm_lock_t lock;
  160 
  161         DRM_COPY_FROM_USER_IOCTL(lock, (drm_lock_t *)data, sizeof(lock));
  162 
  163         if (lock.context == DRM_KERNEL_CONTEXT) {
  164                 DRM_ERROR("Process %d using kernel context %d\n",
  165                     DRM_CURRENTPID, lock.context);
  166                 return EINVAL;
  167         }
  168 
  169         atomic_inc(&dev->counts[_DRM_STAT_UNLOCKS]);
  170 
  171         DRM_LOCK();
  172         drm_lock_transfer(dev, &dev->lock.hw_lock->lock, DRM_KERNEL_CONTEXT);
  173 
  174         if (drm_lock_free(dev, &dev->lock.hw_lock->lock, DRM_KERNEL_CONTEXT)) {
  175                 DRM_ERROR("\n");
  176         }
  177         DRM_UNLOCK();
  178 
  179         return 0;
  180 }

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FreeBSD/Linux Kernel Cross Reference sys/dev/drm/drm_lock.c

FreeBSD/Linux Kernel Cross Reference
sys/dev/drm/drm_lock.c