drm/i915: Pass around sg_table to get_pages/put_pages backend

The plan is to move obj->pages out from under the struct_mutex into its
own per-object lock. We need to prune any assumption of the struct_mutex
from the get_pages/put_pages backends, and to make it easier we pass
around the sg_table to operate on rather than indirectly via the obj.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161028125858.23563-13-chris@chris-wilson.co.uk

1 files changed, 45 insertions, 43 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c
index 0cbc8f70317e..a421447f1d84 100644
--- a/drivers/gpu/drm/i915/i915_gem_userptr.c
+++ b/drivers/gpu/drm/i915/i915_gem_userptr.c
@@ -73,11 +73,14 @@ static void cancel_userptr(struct work_struct *work)
 	/* Cancel any active worker and force us to re-evaluate gup */
 	obj->userptr.work = NULL;
 
-	if (obj->mm.pages) {
-		/* We are inside a kthread context and can't be interrupted */
-		WARN_ON(i915_gem_object_unbind(obj));
-		WARN_ON(__i915_gem_object_put_pages(obj));
-	}
+	/* We are inside a kthread context and can't be interrupted */
+	if (i915_gem_object_unbind(obj) == 0)
+		__i915_gem_object_put_pages(obj);
+	WARN_ONCE(obj->mm.pages,
+		  "Failed to release pages: bind_count=%d, pages_pin_count=%d, pin_display=%d\n",
+		  obj->bind_count,
+		  obj->mm.pages_pin_count,
+		  obj->pin_display);
 
 	i915_gem_object_put(obj);
 	mutex_unlock(&dev->struct_mutex);
@@ -426,24 +429,25 @@ err:
 	return ret;
 }
 
-static int
+static struct sg_table *
 __i915_gem_userptr_set_pages(struct drm_i915_gem_object *obj,
 			     struct page **pvec, int num_pages)
 {
+	struct sg_table *pages;
 	int ret;
 
-	ret = st_set_pages(&obj->mm.pages, pvec, num_pages);
+	ret = st_set_pages(&pages, pvec, num_pages);
 	if (ret)
-		return ret;
+		return ERR_PTR(ret);
 
-	ret = i915_gem_gtt_prepare_object(obj);
+	ret = i915_gem_gtt_prepare_pages(obj, pages);
 	if (ret) {
-		sg_free_table(obj->mm.pages);
-		kfree(obj->mm.pages);
-		obj->mm.pages = NULL;
+		sg_free_table(pages);
+		kfree(pages);
+		return ERR_PTR(ret);
 	}
 
-	return ret;
+	return pages;
 }
 
 static int
@@ -525,20 +529,20 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work)
 
 	mutex_lock(&dev->struct_mutex);
 	if (obj->userptr.work == &work->work) {
+		struct sg_table *pages = ERR_PTR(ret);
+
 		if (pinned == npages) {
-			ret = __i915_gem_userptr_set_pages(obj, pvec, npages);
-			if (ret == 0) {
-				list_add_tail(&obj->global_list,
-					      &to_i915(dev)->mm.unbound_list);
-				obj->mm.get_page.sg_pos = obj->mm.pages->sgl;
-				obj->mm.get_page.sg_idx = 0;
+			pages = __i915_gem_userptr_set_pages(obj, pvec, npages);
+			if (!IS_ERR(pages)) {
+				__i915_gem_object_set_pages(obj, pages);
 				pinned = 0;
+				pages = NULL;
 			}
 		}
-		obj->userptr.work = ERR_PTR(ret);
+
+		obj->userptr.work = ERR_CAST(pages);
 	}
 
-	obj->userptr.workers--;
 	i915_gem_object_put(obj);
 	mutex_unlock(&dev->struct_mutex);
 
@@ -549,7 +553,7 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work)
 	kfree(work);
 }
 
-static int
+static struct sg_table *
 __i915_gem_userptr_get_pages_schedule(struct drm_i915_gem_object *obj,
 				      bool *active)
 {
@@ -574,15 +578,11 @@ __i915_gem_userptr_get_pages_schedule(struct drm_i915_gem_object *obj,
 	 * that error back to this function through
 	 * obj->userptr.work = ERR_PTR.
 	 */
-	if (obj->userptr.workers >= I915_GEM_USERPTR_MAX_WORKERS)
-		return -EAGAIN;
-
 	work = kmalloc(sizeof(*work), GFP_KERNEL);
 	if (work == NULL)
-		return -ENOMEM;
+		return ERR_PTR(-ENOMEM);
 
 	obj->userptr.work = &work->work;
-	obj->userptr.workers++;
 
 	work->obj = i915_gem_object_get(obj);
 
@@ -593,14 +593,15 @@ __i915_gem_userptr_get_pages_schedule(struct drm_i915_gem_object *obj,
 	schedule_work(&work->work);
 
 	*active = true;
-	return -EAGAIN;
+	return ERR_PTR(-EAGAIN);
 }
 
-static int
+static struct sg_table *
 i915_gem_userptr_get_pages(struct drm_i915_gem_object *obj)
 {
 	const int num_pages = obj->base.size >> PAGE_SHIFT;
 	struct page **pvec;
+	struct sg_table *pages;
 	int pinned, ret;
 	bool active;
 
@@ -624,15 +625,15 @@ i915_gem_userptr_get_pages(struct drm_i915_gem_object *obj)
 	if (obj->userptr.work) {
 		/* active flag should still be held for the pending work */
 		if (IS_ERR(obj->userptr.work))
-			return PTR_ERR(obj->userptr.work);
+			return ERR_CAST(obj->userptr.work);
 		else
-			return -EAGAIN;
+			return ERR_PTR(-EAGAIN);
 	}
 
 	/* Let the mmu-notifier know that we have begun and need cancellation */
 	ret = __i915_gem_userptr_set_active(obj, true);
 	if (ret)
-		return ret;
+		return ERR_PTR(ret);
 
 	pvec = NULL;
 	pinned = 0;
@@ -641,7 +642,7 @@ i915_gem_userptr_get_pages(struct drm_i915_gem_object *obj)
 				      GFP_TEMPORARY);
 		if (pvec == NULL) {
 			__i915_gem_userptr_set_active(obj, false);
-			return -ENOMEM;
+			return ERR_PTR(-ENOMEM);
 		}
 
 		pinned = __get_user_pages_fast(obj->userptr.ptr, num_pages,
@@ -650,21 +651,22 @@ i915_gem_userptr_get_pages(struct drm_i915_gem_object *obj)
 
 	active = false;
 	if (pinned < 0)
-		ret = pinned, pinned = 0;
+		pages = ERR_PTR(pinned), pinned = 0;
 	else if (pinned < num_pages)
-		ret = __i915_gem_userptr_get_pages_schedule(obj, &active);
+		pages = __i915_gem_userptr_get_pages_schedule(obj, &active);
 	else
-		ret = __i915_gem_userptr_set_pages(obj, pvec, num_pages);
-	if (ret) {
+		pages = __i915_gem_userptr_set_pages(obj, pvec, num_pages);
+	if (IS_ERR(pages)) {
 		__i915_gem_userptr_set_active(obj, active);
 		release_pages(pvec, pinned, 0);
 	}
 	drm_free_large(pvec);
-	return ret;
+	return pages;
 }
 
 static void
-i915_gem_userptr_put_pages(struct drm_i915_gem_object *obj)
+i915_gem_userptr_put_pages(struct drm_i915_gem_object *obj,
+			   struct sg_table *pages)
 {
 	struct sgt_iter sgt_iter;
 	struct page *page;
@@ -675,9 +677,9 @@ i915_gem_userptr_put_pages(struct drm_i915_gem_object *obj)
 	if (obj->mm.madv != I915_MADV_WILLNEED)
 		obj->mm.dirty = false;
 
-	i915_gem_gtt_finish_object(obj);
+	i915_gem_gtt_finish_pages(obj, pages);
 
-	for_each_sgt_page(page, sgt_iter, obj->mm.pages) {
+	for_each_sgt_page(page, sgt_iter, pages) {
 		if (obj->mm.dirty)
 			set_page_dirty(page);
 
@@ -686,8 +688,8 @@ i915_gem_userptr_put_pages(struct drm_i915_gem_object *obj)
 	}
 	obj->mm.dirty = false;
 
-	sg_free_table(obj->mm.pages);
-	kfree(obj->mm.pages);
+	sg_free_table(pages);
+	kfree(pages);
 }
 
 static void