From 74cf1f91be7f4139601624af0343e3d411190dec Mon Sep 17 00:00:00 2001
From: Owain Gordon Ainsworth <oga@openbsd.org>
Date: Mon, 7 Jul 2008 17:23:48 +0100
Subject: BSD: change drm_locked_task*() to use the same scheme as linux.

The current code can sleep in an interrupt handler, that is bad. So
instead if we can't grab the lock, flag it and run the tasklet on
unlock.

Signed-off-by: Robert Noland <rnoland@2hip.net>
---
 bsd-core/drmP.h     |  1 +
 bsd-core/drm_drv.c  |  1 +
 bsd-core/drm_irq.c  | 45 +++++++++++++++++++++++----------------------
 bsd-core/drm_lock.c |  7 +++++++
 4 files changed, 32 insertions(+), 22 deletions(-)

(limited to 'bsd-core')

diff --git a/bsd-core/drmP.h b/bsd-core/drmP.h
index 88ea4e69..65d7fae4 100644
--- a/bsd-core/drmP.h
+++ b/bsd-core/drmP.h
@@ -739,6 +739,7 @@ struct drm_device {
 	struct mtx	  dev_lock;	/* protects everything else */
 #endif
 	DRM_SPINTYPE	  drw_lock;
+	DRM_SPINTYPE	  tsk_lock;
 
 				/* Usage Counters */
 	int		  open_count;	/* Outstanding files open	   */
diff --git a/bsd-core/drm_drv.c b/bsd-core/drm_drv.c
index 740a8b57..9bd6079f 100644
--- a/bsd-core/drm_drv.c
+++ b/bsd-core/drm_drv.c
@@ -206,6 +206,7 @@ int drm_attach(device_t nbdev, drm_pci_id_list_t *idlist)
 	mtx_init(&dev->irq_lock, "drmirq", NULL, MTX_DEF);
 	mtx_init(&dev->vbl_lock, "drmvbl", NULL, MTX_DEF);
 	mtx_init(&dev->drw_lock, "drmdrw", NULL, MTX_DEF);
+	mtx_init(&dev->tsk_lock, "drmtsk", NULL, MTX_DEF);
 #endif
 
 	id_entry = drm_find_description(pci_get_vendor(dev->device),
diff --git a/bsd-core/drm_irq.c b/bsd-core/drm_irq.c
index c3ecd28b..a066cfc9 100644
--- a/bsd-core/drm_irq.c
+++ b/bsd-core/drm_irq.c
@@ -578,41 +578,42 @@ static void drm_locked_task(void *context, int pending __unused)
 {
 	struct drm_device *dev = context;
 
-	DRM_LOCK();
-	for (;;) {
-		int ret;
-
-		if (drm_lock_take(&dev->lock.hw_lock->lock,
-		    DRM_KERNEL_CONTEXT))
-		{
-			dev->lock.file_priv = NULL; /* kernel owned */
-			dev->lock.lock_time = jiffies;
-			atomic_inc(&dev->counts[_DRM_STAT_LOCKS]);
-			break;  /* Got lock */
-		}
+	DRM_SPINLOCK(&dev->tsk_lock);
 
-		/* Contention */
-#if defined(__FreeBSD__) && __FreeBSD_version > 500000
-		ret = mtx_sleep((void *)&dev->lock.lock_queue, &dev->dev_lock,
-		    PZERO | PCATCH, "drmlk2", 0);
-#else
-		ret = tsleep((void *)&dev->lock.lock_queue, PZERO | PCATCH,
-		    "drmlk2", 0);
-#endif
-		if (ret != 0)
-			return;
+	DRM_LOCK(); /* XXX drm_lock_take() should do it's own locking */
+	if (dev->locked_task_call == NULL ||
+	    drm_lock_take(&dev->lock.hw_lock->lock, DRM_KERNEL_CONTEXT) == 0) {
+		DRM_UNLOCK();
+		DRM_SPINUNLOCK(&dev->tsk_lock);
+		return;
 	}
+
+	dev->lock.file_priv = NULL; /* kernel owned */
+	dev->lock.lock_time = jiffies;
+	atomic_inc(&dev->counts[_DRM_STAT_LOCKS]);
+
 	DRM_UNLOCK();
 
 	dev->locked_task_call(dev);
 
 	drm_lock_free(dev, &dev->lock.hw_lock->lock, DRM_KERNEL_CONTEXT);
+
+	dev->locked_task_call = NULL;
+
+	DRM_SPINUNLOCK(&dev->tsk_lock);
 }
 
 void
 drm_locked_tasklet(struct drm_device *dev,
 		   void (*tasklet)(struct drm_device *dev))
 {
+	DRM_SPINLOCK(&dev->tsk_lock);
+	if (dev->locked_task_call != NULL) {
+		DRM_SPINUNLOCK(&dev->tsk_lock);
+		return;
+	}
+
 	dev->locked_task_call = tasklet;
+	DRM_SPINUNLOCK(&dev->tsk_lock);
 	taskqueue_enqueue(taskqueue_swi, &dev->locked_task);
 }
diff --git a/bsd-core/drm_lock.c b/bsd-core/drm_lock.c
index 9101dec8..80ebb71d 100644
--- a/bsd-core/drm_lock.c
+++ b/bsd-core/drm_lock.c
@@ -180,6 +180,13 @@ int drm_unlock(struct drm_device *dev, void *data, struct drm_file *file_priv)
 	    _DRM_LOCKING_CONTEXT(dev->lock.hw_lock->lock) != lock->context)
 		return EINVAL;
 
+	DRM_SPINLOCK(&dev->tsk_lock);
+	if (dev->locked_task_call != NULL) {
+		dev->locked_task_call(dev);
+		dev->locked_task_call = NULL;
+	}
+	DRM_SPINUNLOCK(&dev->tsk_lock);
+
 	atomic_inc(&dev->counts[_DRM_STAT_UNLOCKS]);
 
 	DRM_LOCK();
-- 
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