diff --git a/drivers/char/drm/drmP.h b/drivers/char/drm/drmP.h
index 09705da..80041d5 100644
--- a/drivers/char/drm/drmP.h
+++ b/drivers/char/drm/drmP.h
@@ -414,6 +414,10 @@
 	struct file *filp;		/**< File descr of lock holder (0=kernel) */
 	wait_queue_head_t lock_queue;	/**< Queue of blocked processes */
 	unsigned long lock_time;	/**< Time of last lock in jiffies */
+	spinlock_t spinlock;
+	uint32_t kernel_waiters;
+	uint32_t user_waiters;
+	int idle_has_lock;
 } drm_lock_data_t;
 
 /**
@@ -590,6 +594,8 @@
 	void (*reclaim_buffers) (struct drm_device * dev, struct file * filp);
 	void (*reclaim_buffers_locked) (struct drm_device *dev,
 					struct file *filp);
+	void (*reclaim_buffers_idlelocked) (struct drm_device *dev,
+					struct file * filp);
 	unsigned long (*get_map_ofs) (drm_map_t * map);
 	unsigned long (*get_reg_ofs) (struct drm_device * dev);
 	void (*set_version) (struct drm_device * dev, drm_set_version_t * sv);
@@ -915,9 +921,18 @@
 		    unsigned int cmd, unsigned long arg);
 extern int drm_unlock(struct inode *inode, struct file *filp,
 		      unsigned int cmd, unsigned long arg);
-extern int drm_lock_take(__volatile__ unsigned int *lock, unsigned int context);
-extern int drm_lock_free(drm_device_t * dev,
-			 __volatile__ unsigned int *lock, unsigned int context);
+extern int drm_lock_take(drm_lock_data_t *lock_data, unsigned int context);
+extern int drm_lock_free(drm_lock_data_t *lock_data, unsigned int context);
+extern void drm_idlelock_take(drm_lock_data_t *lock_data);
+extern void drm_idlelock_release(drm_lock_data_t *lock_data);
+
+/*
+ * These are exported to drivers so that they can implement fencing using
+ * DMA quiscent + idle. DMA quiescent usually requires the hardware lock.
+ */
+
+extern int drm_i_have_hw_lock(struct file *filp);
+extern int drm_kernel_take_hw_lock(struct file *filp);
 
 				/* Buffer management support (drm_bufs.h) */
 extern int drm_addbufs_agp(drm_device_t * dev, drm_buf_desc_t * request);
diff --git a/drivers/char/drm/drm_fops.c b/drivers/char/drm/drm_fops.c
index 314abd9..3b159ca 100644
--- a/drivers/char/drm/drm_fops.c
+++ b/drivers/char/drm/drm_fops.c
@@ -356,58 +356,56 @@
 		  current->pid, (long)old_encode_dev(priv->head->device),
 		  dev->open_count);
 
-	if (priv->lock_count && dev->lock.hw_lock &&
-	    _DRM_LOCK_IS_HELD(dev->lock.hw_lock->lock) &&
-	    dev->lock.filp == filp) {
+	if (dev->driver->reclaim_buffers_locked && dev->lock.hw_lock) {
+		if (drm_i_have_hw_lock(filp)) {
+			dev->driver->reclaim_buffers_locked(dev, filp);
+		} else {
+			unsigned long _end=jiffies + 3*DRM_HZ;
+			int locked = 0;
+
+			drm_idlelock_take(&dev->lock);
+
+			/*
+			 * Wait for a while.
+			 */
+
+			do{
+				spin_lock(&dev->lock.spinlock);
+				locked = dev->lock.idle_has_lock;
+				spin_unlock(&dev->lock.spinlock);
+				if (locked)
+					break;
+				schedule();
+			} while (!time_after_eq(jiffies, _end));
+
+			if (!locked) {
+				DRM_ERROR("reclaim_buffers_locked() deadlock. Please rework this\n"
+					  "\tdriver to use reclaim_buffers_idlelocked() instead.\n"
+					  "\tI will go on reclaiming the buffers anyway.\n");
+			}
+
+			dev->driver->reclaim_buffers_locked(dev, filp);
+			drm_idlelock_release(&dev->lock);
+		}
+	}
+
+	if (dev->driver->reclaim_buffers_idlelocked && dev->lock.hw_lock) {
+
+		drm_idlelock_take(&dev->lock);
+		dev->driver->reclaim_buffers_idlelocked(dev, filp);
+		drm_idlelock_release(&dev->lock);
+
+	}
+
+	if (drm_i_have_hw_lock(filp)) {
 		DRM_DEBUG("File %p released, freeing lock for context %d\n",
 			  filp, _DRM_LOCKING_CONTEXT(dev->lock.hw_lock->lock));
 
-		if (dev->driver->reclaim_buffers_locked)
-			dev->driver->reclaim_buffers_locked(dev, filp);
-
-		drm_lock_free(dev, &dev->lock.hw_lock->lock,
+		drm_lock_free(&dev->lock,
 			      _DRM_LOCKING_CONTEXT(dev->lock.hw_lock->lock));
-
-		/* FIXME: may require heavy-handed reset of
-		   hardware at this point, possibly
-		   processed via a callback to the X
-		   server. */
-	} else if (dev->driver->reclaim_buffers_locked && priv->lock_count
-		   && dev->lock.hw_lock) {
-		/* The lock is required to reclaim buffers */
-		DECLARE_WAITQUEUE(entry, current);
-
-		add_wait_queue(&dev->lock.lock_queue, &entry);
-		for (;;) {
-			__set_current_state(TASK_INTERRUPTIBLE);
-			if (!dev->lock.hw_lock) {
-				/* Device has been unregistered */
-				retcode = -EINTR;
-				break;
-			}
-			if (drm_lock_take(&dev->lock.hw_lock->lock,
-					  DRM_KERNEL_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)) {
-				retcode = -ERESTARTSYS;
-				break;
-			}
-		}
-		__set_current_state(TASK_RUNNING);
-		remove_wait_queue(&dev->lock.lock_queue, &entry);
-		if (!retcode) {
-			dev->driver->reclaim_buffers_locked(dev, filp);
-			drm_lock_free(dev, &dev->lock.hw_lock->lock,
-				      DRM_KERNEL_CONTEXT);
-		}
 	}
 
+
 	if (drm_core_check_feature(dev, DRIVER_HAVE_DMA) &&
 	    !dev->driver->reclaim_buffers_locked) {
 		dev->driver->reclaim_buffers(dev, filp);
diff --git a/drivers/char/drm/drm_irq.c b/drivers/char/drm/drm_irq.c
index 9d00c51..2e75331 100644
--- a/drivers/char/drm/drm_irq.c
+++ b/drivers/char/drm/drm_irq.c
@@ -424,7 +424,7 @@
 	spin_lock_irqsave(&dev->tasklet_lock, irqflags);
 
 	if (!dev->locked_tasklet_func ||
-	    !drm_lock_take(&dev->lock.hw_lock->lock,
+	    !drm_lock_take(&dev->lock,
 			   DRM_KERNEL_CONTEXT)) {
 		spin_unlock_irqrestore(&dev->tasklet_lock, irqflags);
 		return;
@@ -435,7 +435,7 @@
 
 	dev->locked_tasklet_func(dev);
 
-	drm_lock_free(dev, &dev->lock.hw_lock->lock,
+	drm_lock_free(&dev->lock,
 		      DRM_KERNEL_CONTEXT);
 
 	dev->locked_tasklet_func = NULL;
diff --git a/drivers/char/drm/drm_lock.c b/drivers/char/drm/drm_lock.c
index e9993ba..befd1af 100644
--- a/drivers/char/drm/drm_lock.c
+++ b/drivers/char/drm/drm_lock.c
@@ -35,9 +35,6 @@
 
 #include "drmP.h"
 
-static int drm_lock_transfer(drm_device_t * dev,
-			     __volatile__ unsigned int *lock,
-			     unsigned int context);
 static int drm_notifier(void *priv);
 
 /**
@@ -80,6 +77,9 @@
 			return -EINVAL;
 
 	add_wait_queue(&dev->lock.lock_queue, &entry);
+	spin_lock(&dev->lock.spinlock);
+	dev->lock.user_waiters++;
+	spin_unlock(&dev->lock.spinlock);
 	for (;;) {
 		__set_current_state(TASK_INTERRUPTIBLE);
 		if (!dev->lock.hw_lock) {
@@ -87,7 +87,7 @@
 			ret = -EINTR;
 			break;
 		}
-		if (drm_lock_take(&dev->lock.hw_lock->lock, lock.context)) {
+		if (drm_lock_take(&dev->lock, lock.context)) {
 			dev->lock.filp = filp;
 			dev->lock.lock_time = jiffies;
 			atomic_inc(&dev->counts[_DRM_STAT_LOCKS]);
@@ -101,12 +101,14 @@
 			break;
 		}
 	}
+	spin_lock(&dev->lock.spinlock);
+	dev->lock.user_waiters--;
+	spin_unlock(&dev->lock.spinlock);
 	__set_current_state(TASK_RUNNING);
 	remove_wait_queue(&dev->lock.lock_queue, &entry);
 
-	DRM_DEBUG("%d %s\n", lock.context, ret ? "interrupted" : "has lock");
-	if (ret)
-		return ret;
+	DRM_DEBUG( "%d %s\n", lock.context, ret ? "interrupted" : "has lock" );
+	if (ret) return ret;
 
 	sigemptyset(&dev->sigmask);
 	sigaddset(&dev->sigmask, SIGSTOP);
@@ -127,14 +129,12 @@
 		}
 	}
 
-	/* 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);
 	}
+
 	return 0;
 }
 
@@ -184,12 +184,8 @@
 	if (dev->driver->kernel_context_switch_unlock)
 		dev->driver->kernel_context_switch_unlock(dev);
 	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");
+		if (drm_lock_free(&dev->lock,lock.context)) {
+			/* FIXME: Should really bail out here. */
 		}
 	}
 
@@ -206,18 +202,26 @@
  *
  * 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)
+int drm_lock_take(drm_lock_data_t *lock_data,
+		  unsigned int context)
 {
 	unsigned int old, new, prev;
+	volatile unsigned int *lock = &lock_data->hw_lock->lock;
 
+	spin_lock(&lock_data->spinlock);
 	do {
 		old = *lock;
 		if (old & _DRM_LOCK_HELD)
 			new = old | _DRM_LOCK_CONT;
-		else
-			new = context | _DRM_LOCK_HELD;
+		else {
+			new = context | _DRM_LOCK_HELD |
+				((lock_data->user_waiters + lock_data->kernel_waiters > 1) ?
+				 _DRM_LOCK_CONT : 0);
+		}
 		prev = cmpxchg(lock, old, new);
 	} while (prev != old);
+	spin_unlock(&lock_data->spinlock);
+
 	if (_DRM_LOCKING_CONTEXT(old) == context) {
 		if (old & _DRM_LOCK_HELD) {
 			if (context != DRM_KERNEL_CONTEXT) {
@@ -227,7 +231,8 @@
 			return 0;
 		}
 	}
-	if (new == (context | _DRM_LOCK_HELD)) {
+
+	if ((_DRM_LOCKING_CONTEXT(new)) == context && (new & _DRM_LOCK_HELD)) {
 		/* Have lock */
 		return 1;
 	}
@@ -246,13 +251,13 @@
  * Resets the lock file pointer.
  * Marks the lock as held by the given context, via the \p cmpxchg instruction.
  */
-static int drm_lock_transfer(drm_device_t * dev,
-			     __volatile__ unsigned int *lock,
+static int drm_lock_transfer(drm_lock_data_t *lock_data,
 			     unsigned int context)
 {
 	unsigned int old, new, prev;
+	volatile unsigned int *lock = &lock_data->hw_lock->lock;
 
-	dev->lock.filp = NULL;
+	lock_data->filp = NULL;
 	do {
 		old = *lock;
 		new = context | _DRM_LOCK_HELD;
@@ -272,23 +277,32 @@
  * 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)
+int drm_lock_free(drm_lock_data_t *lock_data, unsigned int context)
 {
 	unsigned int old, new, prev;
+	volatile unsigned int *lock = &lock_data->hw_lock->lock;
 
-	dev->lock.filp = NULL;
+	spin_lock(&lock_data->spinlock);
+	if (lock_data->kernel_waiters != 0) {
+		drm_lock_transfer(lock_data, 0);
+		lock_data->idle_has_lock = 1;
+		spin_unlock(&lock_data->spinlock);
+		return 1;
+	}
+	spin_unlock(&lock_data->spinlock);
+
 	do {
 		old = *lock;
-		new = 0;
+		new = _DRM_LOCKING_CONTEXT(old);
 		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);
+	wake_up_interruptible(&lock_data->lock_queue);
 	return 0;
 }
 
@@ -322,3 +336,67 @@
 	} while (prev != old);
 	return 0;
 }
+
+/**
+ * This function returns immediately and takes the hw lock
+ * with the kernel context if it is free, otherwise it gets the highest priority when and if
+ * it is eventually released.
+ *
+ * This guarantees that the kernel will _eventually_ have the lock _unless_ it is held
+ * by a blocked process. (In the latter case an explicit wait for the hardware lock would cause
+ * a deadlock, which is why the "idlelock" was invented).
+ *
+ * This should be sufficient to wait for GPU idle without
+ * having to worry about starvation.
+ */
+
+void drm_idlelock_take(drm_lock_data_t *lock_data)
+{
+	int ret = 0;
+
+	spin_lock(&lock_data->spinlock);
+	lock_data->kernel_waiters++;
+	if (!lock_data->idle_has_lock) {
+
+		spin_unlock(&lock_data->spinlock);
+		ret = drm_lock_take(lock_data, DRM_KERNEL_CONTEXT);
+		spin_lock(&lock_data->spinlock);
+
+		if (ret == 1)
+			lock_data->idle_has_lock = 1;
+	}
+	spin_unlock(&lock_data->spinlock);
+}
+EXPORT_SYMBOL(drm_idlelock_take);
+
+void drm_idlelock_release(drm_lock_data_t *lock_data)
+{
+	unsigned int old, prev;
+	volatile unsigned int *lock = &lock_data->hw_lock->lock;
+
+	spin_lock(&lock_data->spinlock);
+	if (--lock_data->kernel_waiters == 0) {
+		if (lock_data->idle_has_lock) {
+			do {
+				old = *lock;
+				prev = cmpxchg(lock, old, DRM_KERNEL_CONTEXT);
+			} while (prev != old);
+			wake_up_interruptible(&lock_data->lock_queue);
+			lock_data->idle_has_lock = 0;
+		}
+	}
+	spin_unlock(&lock_data->spinlock);
+}
+EXPORT_SYMBOL(drm_idlelock_release);
+
+
+int drm_i_have_hw_lock(struct file *filp)
+{
+	DRM_DEVICE;
+
+	return (priv->lock_count && dev->lock.hw_lock &&
+		_DRM_LOCK_IS_HELD(dev->lock.hw_lock->lock) &&
+		dev->lock.filp == filp);
+}
+
+EXPORT_SYMBOL(drm_i_have_hw_lock);
diff --git a/drivers/char/drm/drm_stub.c b/drivers/char/drm/drm_stub.c
index 120d102..19408ad 100644
--- a/drivers/char/drm/drm_stub.c
+++ b/drivers/char/drm/drm_stub.c
@@ -62,6 +62,7 @@
 	spin_lock_init(&dev->count_lock);
 	spin_lock_init(&dev->drw_lock);
 	spin_lock_init(&dev->tasklet_lock);
+	spin_lock_init(&dev->lock.spinlock);
 	init_timer(&dev->timer);
 	mutex_init(&dev->struct_mutex);
 	mutex_init(&dev->ctxlist_mutex);
diff --git a/drivers/char/drm/sis_drv.c b/drivers/char/drm/sis_drv.c
index 3d5b321..690e0af 100644
--- a/drivers/char/drm/sis_drv.c
+++ b/drivers/char/drm/sis_drv.c
@@ -71,7 +71,7 @@
 	.context_dtor = NULL,
 	.dma_quiescent = sis_idle,
 	.reclaim_buffers = NULL,
-	.reclaim_buffers_locked = sis_reclaim_buffers_locked,
+	.reclaim_buffers_idlelocked = sis_reclaim_buffers_locked,
 	.lastclose = sis_lastclose,
 	.get_map_ofs = drm_core_get_map_ofs,
 	.get_reg_ofs = drm_core_get_reg_ofs,
diff --git a/drivers/char/drm/via_drv.c b/drivers/char/drm/via_drv.c
index bb9dde8..2d4957a 100644
--- a/drivers/char/drm/via_drv.c
+++ b/drivers/char/drm/via_drv.c
@@ -52,7 +52,8 @@
 	.dma_quiescent = via_driver_dma_quiescent,
 	.dri_library_name = dri_library_name,
 	.reclaim_buffers = drm_core_reclaim_buffers,
-	.reclaim_buffers_locked = via_reclaim_buffers_locked,
+	.reclaim_buffers_locked = NULL,
+	.reclaim_buffers_idlelocked = via_reclaim_buffers_locked,
 	.lastclose = via_lastclose,
 	.get_map_ofs = drm_core_get_map_ofs,
 	.get_reg_ofs = drm_core_get_reg_ofs,