[RFC PATCH 046/162] drm/i915: Add ww locking to dma-buf ops.

[Matthew Auld <matthew.auld@intel.com>]

From: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

vmap is using pin_pages, but needs to use ww locking,
add pin_pages_unlocked to correctly lock the mapping.

Also add ww locking to begin/end cpu access.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 60 ++++++++++++----------
 1 file changed, 33 insertions(+), 27 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
index 36e3c2765f4c..c4b01e819786 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
@@ -82,7 +82,7 @@ static int i915_gem_dmabuf_vmap(struct dma_buf *dma_buf, struct dma_buf_map *map
 	struct drm_i915_gem_object *obj = dma_buf_to_obj(dma_buf);
 	void *vaddr;
 
-	vaddr = i915_gem_object_pin_map(obj, I915_MAP_WB);
+	vaddr = i915_gem_object_pin_map_unlocked(obj, I915_MAP_WB);
 	if (IS_ERR(vaddr))
 		return PTR_ERR(vaddr);
 
@@ -123,42 +123,48 @@ static int i915_gem_begin_cpu_access(struct dma_buf *dma_buf, enum dma_data_dire
 {
 	struct drm_i915_gem_object *obj = dma_buf_to_obj(dma_buf);
 	bool write = (direction == DMA_BIDIRECTIONAL || direction == DMA_TO_DEVICE);
+	struct i915_gem_ww_ctx ww;
 	int err;
 
-	err = i915_gem_object_pin_pages(obj);
-	if (err)
-		return err;
-
-	err = i915_gem_object_lock_interruptible(obj, NULL);
-	if (err)
-		goto out;
-
-	err = i915_gem_object_set_to_cpu_domain(obj, write);
-	i915_gem_object_unlock(obj);
-
-out:
-	i915_gem_object_unpin_pages(obj);
+	i915_gem_ww_ctx_init(&ww, true);
+retry:
+	err = i915_gem_object_lock(obj, &ww);
+	if (!err)
+		err = i915_gem_object_pin_pages(obj);
+	if (!err) {
+		err = i915_gem_object_set_to_cpu_domain(obj, write);
+		i915_gem_object_unpin_pages(obj);
+	}
+	if (err == -EDEADLK) {
+		err = i915_gem_ww_ctx_backoff(&ww);
+		if (!err)
+			goto retry;
+	}
+	i915_gem_ww_ctx_fini(&ww);
 	return err;
 }
 
 static int i915_gem_end_cpu_access(struct dma_buf *dma_buf, enum dma_data_direction direction)
 {
 	struct drm_i915_gem_object *obj = dma_buf_to_obj(dma_buf);
+	struct i915_gem_ww_ctx ww;
 	int err;
 
-	err = i915_gem_object_pin_pages(obj);
-	if (err)
-		return err;
-
-	err = i915_gem_object_lock_interruptible(obj, NULL);
-	if (err)
-		goto out;
-
-	err = i915_gem_object_set_to_gtt_domain(obj, false);
-	i915_gem_object_unlock(obj);
-
-out:
-	i915_gem_object_unpin_pages(obj);
+	i915_gem_ww_ctx_init(&ww, true);
+retry:
+	err = i915_gem_object_lock(obj, &ww);
+	if (!err)
+		err = i915_gem_object_pin_pages(obj);
+	if (!err) {
+		err = i915_gem_object_set_to_gtt_domain(obj, false);
+		i915_gem_object_unpin_pages(obj);
+	}
+	if (err == -EDEADLK) {
+		err = i915_gem_ww_ctx_backoff(&ww);
+		if (!err)
+			goto retry;
+	}
+	i915_gem_ww_ctx_fini(&ww);
 	return err;
 }
 
-- 
2.26.2

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