1 files changed, 303 insertions, 0 deletions

diff --git a/drivers/char/drm/drm_lock.c b/drivers/char/drm/drm_lock.c
new file mode 100644
index 000000000000..d0d6fc661625
--- /dev/null
+++ b/drivers/char/drm/drm_lock.c
@@ -0,0 +1,303 @@
+/**
+ * \file drm_lock.h 
+ * IOCTLs for locking
+ * 
+ * \author Rickard E. (Rik) Faith <faith@valinux.com>
+ * \author Gareth Hughes <gareth@valinux.com>
+ */
+
+/*
+ * Created: Tue Feb  2 08:37:54 1999 by faith@valinux.com
+ *
+ * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
+ * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
+ * All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include "drmP.h"
+
+/** 
+ * Lock ioctl.
+ *
+ * \param inode device inode.
+ * \param filp file pointer.
+ * \param cmd command.
+ * \param arg user argument, pointing to a drm_lock structure.
+ * \return zero on success or negative number on failure.
+ *
+ * Add the current task to the lock wait queue, and attempt to take to lock.
+ */
+int drm_lock( struct inode *inode, struct file *filp,
+               unsigned int cmd, unsigned long arg )
+{
+        drm_file_t *priv = filp->private_data;
+        drm_device_t *dev = priv->head->dev;
+        DECLARE_WAITQUEUE( entry, current );
+        drm_lock_t lock;
+        int ret = 0;
+
+        ++priv->lock_count;
+
+        if ( copy_from_user( &lock, (drm_lock_t __user *)arg, sizeof(lock) ) )
+                return -EFAULT;
+
+        if ( lock.context == DRM_KERNEL_CONTEXT ) {
+                DRM_ERROR( "Process %d using kernel context %d\n",
+                           current->pid, lock.context );
+                return -EINVAL;
+        }
+
+        DRM_DEBUG( "%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n",
+                   lock.context, current->pid,
+                   dev->lock.hw_lock->lock, lock.flags );
+
+        if (drm_core_check_feature(dev, DRIVER_DMA_QUEUE))
+                if ( lock.context < 0 )
+                        return -EINVAL;
+
+        add_wait_queue( &dev->lock.lock_queue, &entry );
+        for (;;) {
+                __set_current_state(TASK_INTERRUPTIBLE);
+                if ( !dev->lock.hw_lock ) {
+                        /* Device has been unregistered */
+                        ret = -EINTR;
+                        break;
+                }
+                if ( drm_lock_take( &dev->lock.hw_lock->lock,
+                                     lock.context ) ) {
+                        dev->lock.filp      = filp;
+                        dev->lock.lock_time = jiffies;
+                        atomic_inc( &dev->counts[_DRM_STAT_LOCKS] );
+                        break;  /* Got lock */
+                }
+                
+                /* Contention */
+                schedule();
+                if ( signal_pending( current ) ) {
+                        ret = -ERESTARTSYS;
+                        break;
+                }
+        }
+        __set_current_state(TASK_RUNNING);
+        remove_wait_queue( &dev->lock.lock_queue, &entry );
+
+        sigemptyset( &dev->sigmask );
+        sigaddset( &dev->sigmask, SIGSTOP );
+        sigaddset( &dev->sigmask, SIGTSTP );
+        sigaddset( &dev->sigmask, SIGTTIN );
+        sigaddset( &dev->sigmask, SIGTTOU );
+        dev->sigdata.context = lock.context;
+        dev->sigdata.lock    = dev->lock.hw_lock;
+        block_all_signals( drm_notifier,
+                           &dev->sigdata, &dev->sigmask );
+        
+        if (dev->driver->dma_ready && (lock.flags & _DRM_LOCK_READY))
+                dev->driver->dma_ready(dev);
+        
+        if ( dev->driver->dma_quiescent && (lock.flags & _DRM_LOCK_QUIESCENT ))
+                return dev->driver->dma_quiescent(dev);
+        
+        /* dev->driver->kernel_context_switch isn't used by any of the x86 
+         *  drivers but is used by the Sparc driver.
+         */
+        
+        if (dev->driver->kernel_context_switch && 
+            dev->last_context != lock.context) {
+          dev->driver->kernel_context_switch(dev, dev->last_context, 
+                                            lock.context);
+        }
+        DRM_DEBUG( "%d %s\n", lock.context, ret ? "interrupted" : "has lock" );
+
+        return ret;
+}
+
+/** 
+ * Unlock ioctl.
+ *
+ * \param inode device inode.
+ * \param filp file pointer.
+ * \param cmd command.
+ * \param arg user argument, pointing to a drm_lock structure.
+ * \return zero on success or negative number on failure.
+ *
+ * Transfer and free the lock.
+ */
+int drm_unlock( struct inode *inode, struct file *filp,
+                 unsigned int cmd, unsigned long arg )
+{
+        drm_file_t *priv = filp->private_data;
+        drm_device_t *dev = priv->head->dev;
+        drm_lock_t lock;
+
+        if ( copy_from_user( &lock, (drm_lock_t __user *)arg, sizeof(lock) ) )
+                return -EFAULT;
+
+        if ( lock.context == DRM_KERNEL_CONTEXT ) {
+                DRM_ERROR( "Process %d using kernel context %d\n",
+                           current->pid, lock.context );
+                return -EINVAL;
+        }
+
+        atomic_inc( &dev->counts[_DRM_STAT_UNLOCKS] );
+
+        /* kernel_context_switch isn't used by any of the x86 drm
+         * modules but is required by the Sparc driver.
+         */
+        if (dev->driver->kernel_context_switch_unlock)
+                dev->driver->kernel_context_switch_unlock(dev, &lock);
+        else {
+                drm_lock_transfer( dev, &dev->lock.hw_lock->lock, 
+                                    DRM_KERNEL_CONTEXT );
+                
+                if ( drm_lock_free( dev, &dev->lock.hw_lock->lock,
+                                     DRM_KERNEL_CONTEXT ) ) {
+                        DRM_ERROR( "\n" );
+                }
+        }
+
+        unblock_all_signals();
+        return 0;
+}
+
+/**
+ * Take the heavyweight lock.
+ *
+ * \param lock lock pointer.
+ * \param context locking context.
+ * \return one if the lock is held, or zero otherwise.
+ *
+ * Attempt to mark the lock as held by the given context, via the \p cmpxchg instruction.
+ */
+int drm_lock_take(__volatile__ unsigned int *lock, unsigned int context)
+{
+        unsigned int old, new, prev;
+
+        do {
+                old = *lock;
+                if (old & _DRM_LOCK_HELD) new = old | _DRM_LOCK_CONT;
+                else                      new = context | _DRM_LOCK_HELD;
+                prev = cmpxchg(lock, old, new);
+        } while (prev != old);
+        if (_DRM_LOCKING_CONTEXT(old) == context) {
+                if (old & _DRM_LOCK_HELD) {
+                        if (context != DRM_KERNEL_CONTEXT) {
+                                DRM_ERROR("%d holds heavyweight lock\n",
+                                          context);
+                        }
+                        return 0;
+                }
+        }
+        if (new == (context | _DRM_LOCK_HELD)) {
+                                /* Have lock */
+                return 1;
+        }
+        return 0;
+}
+
+/**
+ * This takes a lock forcibly and hands it to context.  Should ONLY be used
+ * inside *_unlock to give lock to kernel before calling *_dma_schedule. 
+ * 
+ * \param dev DRM device.
+ * \param lock lock pointer.
+ * \param context locking context.
+ * \return always one.
+ *
+ * Resets the lock file pointer.
+ * Marks the lock as held by the given context, via the \p cmpxchg instruction.
+ */
+int drm_lock_transfer(drm_device_t *dev,
+                       __volatile__ unsigned int *lock, unsigned int context)
+{
+        unsigned int old, new, prev;
+
+        dev->lock.filp = NULL;
+        do {
+                old  = *lock;
+                new  = context | _DRM_LOCK_HELD;
+                prev = cmpxchg(lock, old, new);
+        } while (prev != old);
+        return 1;
+}
+
+/**
+ * Free lock.
+ * 
+ * \param dev DRM device.
+ * \param lock lock.
+ * \param context context.
+ * 
+ * Resets the lock file pointer.
+ * Marks the lock as not held, via the \p cmpxchg instruction. Wakes any task
+ * waiting on the lock queue.
+ */
+int drm_lock_free(drm_device_t *dev,
+                   __volatile__ unsigned int *lock, unsigned int context)
+{
+        unsigned int old, new, prev;
+
+        dev->lock.filp = NULL;
+        do {
+                old  = *lock;
+                new  = 0;
+                prev = cmpxchg(lock, old, new);
+        } while (prev != old);
+        if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) {
+                DRM_ERROR("%d freed heavyweight lock held by %d\n",
+                          context,
+                          _DRM_LOCKING_CONTEXT(old));
+                return 1;
+        }
+        wake_up_interruptible(&dev->lock.lock_queue);
+        return 0;
+}
+
+/**
+ * If we get here, it means that the process has called DRM_IOCTL_LOCK
+ * without calling DRM_IOCTL_UNLOCK.
+ *
+ * If the lock is not held, then let the signal proceed as usual.  If the lock
+ * is held, then set the contended flag and keep the signal blocked.
+ *
+ * \param priv pointer to a drm_sigdata structure.
+ * \return one if the signal should be delivered normally, or zero if the
+ * signal should be blocked.
+ */
+int drm_notifier(void *priv)
+{
+        drm_sigdata_t *s = (drm_sigdata_t *)priv;
+        unsigned int  old, new, prev;
+
+
+                                /* Allow signal delivery if lock isn't held */
+        if (!s->lock || !_DRM_LOCK_IS_HELD(s->lock->lock)
+            || _DRM_LOCKING_CONTEXT(s->lock->lock) != s->context) return 1;
+
+                                /* Otherwise, set flag to force call to
+                                   drmUnlock */
+        do {
+                old  = s->lock->lock;
+                new  = old | _DRM_LOCK_CONT;
+                prev = cmpxchg(&s->lock->lock, old, new);
+        } while (prev != old);
+        return 0;
+}