[3/4] dma-buf: dma-buf: stop mapping sg_tables on attach

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 5baa83b85515..357b94a3dbaa 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -782,7 +782,7 @@  static void mangle_sg_table(struct sg_table *sg_table)
 
 	/* To catch abuse of the underlying struct page by importers mix
 	 * up the bits, but take care to preserve the low SG_ bits to
-	 * not corrupt the sgt. The mixing is undone in __unmap_dma_buf
+	 * not corrupt the sgt. The mixing is undone on unmap
 	 * before passing the sgt back to the exporter.
 	 */
 	for_each_sgtable_sg(sg_table, sg, i)
@@ -790,29 +790,20 @@  static void mangle_sg_table(struct sg_table *sg_table)
 #endif
 
 }
-static struct sg_table *__map_dma_buf(struct dma_buf_attachment *attach,
-				       enum dma_data_direction direction)
-{
-	struct sg_table *sg_table;
-	signed long ret;
-
-	sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
-	if (IS_ERR_OR_NULL(sg_table))
-		return sg_table;
-
-	if (!dma_buf_attachment_is_dynamic(attach)) {
-		ret = dma_resv_wait_timeout(attach->dmabuf->resv,
-					    DMA_RESV_USAGE_KERNEL, true,
-					    MAX_SCHEDULE_TIMEOUT);
-		if (ret < 0) {
-			attach->dmabuf->ops->unmap_dma_buf(attach, sg_table,
-							   direction);
-			return ERR_PTR(ret);
-		}
-	}
 
-	mangle_sg_table(sg_table);
-	return sg_table;
+/**
+ * dma_buf_pin_on_map - check if a DMA-buf should be pinned when mapped
+ * @attach: the DMA-buf attachment to check
+ *
+ * Returns: True if a DMA-buf export provided pin/unpin callbacks and we can't
+ * use the importers move notify for some reason.
+ */
+static bool
+dma_buf_pin_on_map(struct dma_buf_attachment *attach)
+{
+	return attach->dmabuf->ops->pin &&
+		(!IS_ENABLED(CONFIG_DMABUF_MOVE_NOTIFY) ||
+		 !attach->importer_ops);
 }
 
 /**
@@ -935,48 +926,11 @@  dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev,
 	list_add(&attach->node, &dmabuf->attachments);
 	dma_resv_unlock(dmabuf->resv);
 
-	/* When either the importer or the exporter can't handle dynamic
-	 * mappings we cache the mapping here to avoid issues with the
-	 * reservation object lock.
-	 */
-	if (dma_buf_attachment_is_dynamic(attach) !=
-	    dma_buf_is_dynamic(dmabuf)) {
-		struct sg_table *sgt;
-
-		dma_resv_lock(attach->dmabuf->resv, NULL);
-		if (dma_buf_is_dynamic(attach->dmabuf)) {
-			ret = dmabuf->ops->pin(attach);
-			if (ret)
-				goto err_unlock;
-		}
-
-		sgt = __map_dma_buf(attach, DMA_BIDIRECTIONAL);
-		if (!sgt)
-			sgt = ERR_PTR(-ENOMEM);
-		if (IS_ERR(sgt)) {
-			ret = PTR_ERR(sgt);
-			goto err_unpin;
-		}
-		dma_resv_unlock(attach->dmabuf->resv);
-		attach->sgt = sgt;
-		attach->dir = DMA_BIDIRECTIONAL;
-	}
-
 	return attach;
 
 err_attach:
 	kfree(attach);
 	return ERR_PTR(ret);
-
-err_unpin:
-	if (dma_buf_is_dynamic(attach->dmabuf))
-		dmabuf->ops->unpin(attach);
-
-err_unlock:
-	dma_resv_unlock(attach->dmabuf->resv);
-
-	dma_buf_detach(dmabuf, attach);
-	return ERR_PTR(ret);
 }
 EXPORT_SYMBOL_NS_GPL(dma_buf_dynamic_attach, "DMA_BUF");
 
@@ -995,16 +949,6 @@  struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
 }
 EXPORT_SYMBOL_NS_GPL(dma_buf_attach, "DMA_BUF");
 
-static void __unmap_dma_buf(struct dma_buf_attachment *attach,
-			    struct sg_table *sg_table,
-			    enum dma_data_direction direction)
-{
-	/* uses XOR, hence this unmangles */
-	mangle_sg_table(sg_table);
-
-	attach->dmabuf->ops->unmap_dma_buf(attach, sg_table, direction);
-}
-
 /**
  * dma_buf_detach - Remove the given attachment from dmabuf's attachments list
  * @dmabuf:	[in]	buffer to detach from.
@@ -1022,11 +966,12 @@  void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
 	dma_resv_lock(dmabuf->resv, NULL);
 
 	if (attach->sgt) {
+		mangle_sg_table(attach->sgt);
+		attach->dmabuf->ops->unmap_dma_buf(attach, attach->sgt,
+						   attach->dir);
 
-		__unmap_dma_buf(attach, attach->sgt, attach->dir);
-
-		if (dma_buf_is_dynamic(attach->dmabuf))
-			dmabuf->ops->unpin(attach);
+		if (dma_buf_pin_on_map(attach))
+			dma_buf_unpin(attach);
 	}
 	list_del(&attach->node);
 
@@ -1058,7 +1003,7 @@  int dma_buf_pin(struct dma_buf_attachment *attach)
 	struct dma_buf *dmabuf = attach->dmabuf;
 	int ret = 0;
 
-	WARN_ON(!dma_buf_attachment_is_dynamic(attach));
+	WARN_ON(!attach->importer_ops);
 
 	dma_resv_assert_held(dmabuf->resv);
 
@@ -1081,7 +1026,7 @@  void dma_buf_unpin(struct dma_buf_attachment *attach)
 {
 	struct dma_buf *dmabuf = attach->dmabuf;
 
-	WARN_ON(!dma_buf_attachment_is_dynamic(attach));
+	WARN_ON(!attach->importer_ops);
 
 	dma_resv_assert_held(dmabuf->resv);
 
@@ -1115,7 +1060,7 @@  struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
 					enum dma_data_direction direction)
 {
 	struct sg_table *sg_table;
-	int r;
+	signed long ret;
 
 	might_sleep();
 
@@ -1136,29 +1081,37 @@  struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
 		return attach->sgt;
 	}
 
-	if (dma_buf_is_dynamic(attach->dmabuf)) {
-		if (!IS_ENABLED(CONFIG_DMABUF_MOVE_NOTIFY)) {
-			r = attach->dmabuf->ops->pin(attach);
-			if (r)
-				return ERR_PTR(r);
-		}
+	if (dma_buf_pin_on_map(attach)) {
+		ret = attach->dmabuf->ops->pin(attach);
+		if (ret)
+			return ERR_PTR(ret);
 	}
 
-	sg_table = __map_dma_buf(attach, direction);
+	sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
 	if (!sg_table)
 		sg_table = ERR_PTR(-ENOMEM);
+	if (IS_ERR(sg_table))
+		goto error_unpin;
 
-	if (IS_ERR(sg_table) && dma_buf_is_dynamic(attach->dmabuf) &&
-	     !IS_ENABLED(CONFIG_DMABUF_MOVE_NOTIFY))
-		attach->dmabuf->ops->unpin(attach);
+	/*
+	 * When not providing ops the importer doesn't wait for fences either.
+	 */
+	if (!attach->importer_ops) {
+		ret = dma_resv_wait_timeout(attach->dmabuf->resv,
+					    DMA_RESV_USAGE_KERNEL, true,
+					    MAX_SCHEDULE_TIMEOUT);
+		if (ret < 0)
+			goto error_unmap;
+	}
+	mangle_sg_table(sg_table);
 
-	if (!IS_ERR(sg_table) && attach->dmabuf->ops->cache_sgt_mapping) {
+	if (attach->dmabuf->ops->cache_sgt_mapping) {
 		attach->sgt = sg_table;
 		attach->dir = direction;
 	}
 
 #ifdef CONFIG_DMA_API_DEBUG
-	if (!IS_ERR(sg_table)) {
+	{
 		struct scatterlist *sg;
 		u64 addr;
 		int len;
@@ -1175,6 +1128,16 @@  struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
 	}
 #endif /* CONFIG_DMA_API_DEBUG */
 	return sg_table;
+
+error_unmap:
+	attach->dmabuf->ops->unmap_dma_buf(attach, sg_table, direction);
+	sg_table = ERR_PTR(ret);
+
+error_unpin:
+	if (dma_buf_pin_on_map(attach))
+		attach->dmabuf->ops->unpin(attach);
+
+	return sg_table;
 }
 EXPORT_SYMBOL_NS_GPL(dma_buf_map_attachment, "DMA_BUF");
 
@@ -1230,11 +1193,11 @@  void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
 	if (attach->sgt == sg_table)
 		return;
 
-	__unmap_dma_buf(attach, sg_table, direction);
+	mangle_sg_table(sg_table);
+	attach->dmabuf->ops->unmap_dma_buf(attach, sg_table, direction);
 
-	if (dma_buf_is_dynamic(attach->dmabuf) &&
-	    !IS_ENABLED(CONFIG_DMABUF_MOVE_NOTIFY))
-		dma_buf_unpin(attach);
+	if (dma_buf_pin_on_map(attach))
+		attach->dmabuf->ops->unpin(attach);
 }
 EXPORT_SYMBOL_NS_GPL(dma_buf_unmap_attachment, "DMA_BUF");
 
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index 36216d28d8bd..c54ff2dda8cb 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -583,20 +583,6 @@  static inline bool dma_buf_is_dynamic(struct dma_buf *dmabuf)
 	return !!dmabuf->ops->pin;
 }
 
-/**
- * dma_buf_attachment_is_dynamic - check if a DMA-buf attachment uses dynamic
- * mappings
- * @attach: the DMA-buf attachment to check
- *
- * Returns true if a DMA-buf importer wants to call the map/unmap functions with
- * the dma_resv lock held.
- */
-static inline bool
-dma_buf_attachment_is_dynamic(struct dma_buf_attachment *attach)
-{
-	return !!attach->importer_ops;
-}
-
 struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
 					  struct device *dev);
 struct dma_buf_attachment *