7 files changed, 174 insertions, 81 deletions

diff --git a/drivers/char/drm/drmP.h b/drivers/char/drm/drmP.h
index 09705da8cdd7..80041d5b792d 100644
--- a/drivers/char/drm/drmP.h
+++ b/drivers/char/drm/drmP.h
@@ -414,6 +414,10 @@ typedef struct drm_lock_data {
         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 @@ struct drm_driver {
         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 @@ extern int drm_lock(struct inode *inode, struct file *filp,
                     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 314abd9d6510..3b159cab3bc8 100644
--- a/drivers/char/drm/drm_fops.c
+++ b/drivers/char/drm/drm_fops.c
@@ -356,58 +356,56 @@ int drm_release(struct inode *inode, struct file *filp)
                   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) {
-                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)
+        if (dev->driver->reclaim_buffers_locked && dev->lock.hw_lock) {
+                if (drm_i_have_hw_lock(filp)) {
                         dev->driver->reclaim_buffers_locked(dev, filp);
-
-                drm_lock_free(dev, &dev->lock.hw_lock->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;
+                } 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");
                         }
-                        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);
+                        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));
+
+                drm_lock_free(&dev->lock,
+                              _DRM_LOCKING_CONTEXT(dev->lock.hw_lock->lock));
+        }
+
+
         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 9d00c51fe2c4..2e75331fd83e 100644
--- a/drivers/char/drm/drm_irq.c
+++ b/drivers/char/drm/drm_irq.c
@@ -424,7 +424,7 @@ static void drm_locked_tasklet_func(unsigned long data)
         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 @@ static void drm_locked_tasklet_func(unsigned long data)
 
         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 e9993ba461a2..befd1af19dfe 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 @@ int drm_lock(struct inode *inode, struct file *filp,
                         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 @@ int drm_lock(struct inode *inode, struct file *filp,
                         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 @@ int drm_lock(struct inode *inode, struct file *filp,
                         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 @@ int drm_lock(struct inode *inode, struct file *filp,
                 }
         }
 
-        /* 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 @@ int drm_unlock(struct inode *inode, struct file *filp,
         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 @@ int drm_unlock(struct inode *inode, struct file *filp,
  *
  * 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 @@ int drm_lock_take(__volatile__ unsigned int *lock, unsigned int context)
                         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 @@ int drm_lock_take(__volatile__ unsigned int *lock, unsigned int context)
  * 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 @@ static int drm_lock_transfer(drm_device_t * dev,
  * 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;
+
+        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);
 
-        dev->lock.filp = NULL;
         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 @@ static int drm_notifier(void *priv)
         } 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 120d10256feb..19408adcc775 100644
--- a/drivers/char/drm/drm_stub.c
+++ b/drivers/char/drm/drm_stub.c
@@ -62,6 +62,7 @@ static int drm_fill_in_dev(drm_device_t * dev, struct pci_dev *pdev,
         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 3d5b3218b6ff..690e0af8e7c2 100644
--- a/drivers/char/drm/sis_drv.c
+++ b/drivers/char/drm/sis_drv.c
@@ -71,7 +71,7 @@ static struct drm_driver driver = {
         .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 bb9dde8b1911..2d4957ab256a 100644
--- a/drivers/char/drm/via_drv.c
+++ b/drivers/char/drm/via_drv.c
@@ -52,7 +52,8 @@ static struct drm_driver driver = {
         .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,