[Intel-gfx] [PATCH 173/190] drm/i915: Wait upon userptr get-user-pages within execbuffer

[Chris Wilson]

This simply hides the EAGAIN caused by userptr when userspace causes
resource contention.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_dma.c            |  1 +
 drivers/gpu/drm/i915/i915_drv.h            |  8 ++++++++
 drivers/gpu/drm/i915/i915_gem_execbuffer.c |  3 +++
 drivers/gpu/drm/i915/i915_gem_userptr.c    | 16 +++++++++++++---
 4 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 7d85c3bea02a..c1afbd873197 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -1192,6 +1192,7 @@ int i915_driver_unload(struct drm_device *dev)
 	mutex_unlock(&dev->struct_mutex);
 	intel_fbc_cleanup_cfb(dev_priv);
 	i915_gem_cleanup_stolen(dev);
+	i915_gem_cleanup_userptr(dev);
 
 	intel_csr_ucode_fini(dev_priv);
 
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 601ef7412cf9..a4311e2d2140 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1295,6 +1295,13 @@ struct i915_gem_mm {
 	struct delayed_work idle_work;
 
 	/**
+	 * Workqueue to fault in userptr pages, flushed by the execbuf
+	 * when required but otherwise left to userspace to try again
+	 * on EAGAIN.
+	 */
+	struct workqueue_struct *userptr_wq;
+
+	/**
 	 * Are we in a non-interruptible section of code like
 	 * modesetting?
 	 */
@@ -2724,6 +2731,7 @@ int i915_gem_set_tiling(struct drm_device *dev, void *data,
 int i915_gem_get_tiling(struct drm_device *dev, void *data,
 			struct drm_file *file_priv);
 int i915_gem_init_userptr(struct drm_device *dev);
+void i915_gem_cleanup_userptr(struct drm_device *dev);
 int i915_gem_userptr_ioctl(struct drm_device *dev, void *data,
 			   struct drm_file *file);
 int i915_gem_get_aperture_ioctl(struct drm_device *dev, void *data,
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index f40d3254249a..733250afa139 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -1133,6 +1133,9 @@ repeat:
 		}
 	}
 
+	/* A frequent cause for EAGAIN are currently unavailable client pages */
+	flush_workqueue(eb->i915->mm.userptr_wq);
+
 	ret = i915_mutex_lock_interruptible(dev);
 	if (ret) {
 		mutex_lock(&dev->struct_mutex);
diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c
index 232ce85b39db..54385f6c7e14 100644
--- a/drivers/gpu/drm/i915/i915_gem_userptr.c
+++ b/drivers/gpu/drm/i915/i915_gem_userptr.c
@@ -102,7 +102,8 @@ static unsigned long cancel_userptr(struct i915_mmu_object *mo)
 	 * is freed and then double free it.
 	 */
 	if (mo->active && kref_get_unless_zero(&mo->obj->base.refcount)) {
-		schedule_work(&mo->work);
+		queue_work(to_i915(mo->obj->base.dev)->mm.userptr_wq,
+			   &mo->work);
 		/* only schedule one work packet to avoid the refleak */
 		mo->active = false;
 	}
@@ -450,7 +451,7 @@ __i915_mm_struct_free(struct kref *kref)
 	mutex_unlock(&to_i915(mm->dev)->mm_lock);
 
 	INIT_WORK(&mm->work, __i915_mm_struct_free__worker);
-	schedule_work(&mm->work);
+	queue_work(to_i915(mm->dev)->mm.userptr_wq, &mm->work);
 }
 
 static void
@@ -664,7 +665,7 @@ __i915_gem_userptr_get_pages_schedule(struct drm_i915_gem_object *obj,
 	get_task_struct(work->task);
 
 	INIT_WORK(&work->work, __i915_gem_userptr_get_pages_worker);
-	schedule_work(&work->work);
+	queue_work(to_i915(obj->base.dev)->mm.userptr_wq, &work->work);
 
 	*active = true;
 	return -EAGAIN;
@@ -886,5 +887,14 @@ i915_gem_init_userptr(struct drm_device *dev)
 	struct drm_i915_private *dev_priv = to_i915(dev);
 	mutex_init(&dev_priv->mm_lock);
 	hash_init(dev_priv->mm_structs);
+	dev_priv->mm.userptr_wq =
+		alloc_workqueue("i915-userptr", WQ_HIGHPRI, 0);
 	return 0;
 }
+
+void
+i915_gem_cleanup_userptr(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = to_i915(dev);
+	destroy_workqueue(dev_priv->mm.userptr_wq);
+}
-- 
2.7.0.rc3