[PATCH] dma-buf: add meta data attachment - Linaro-mm-sig

21 Mar 2014

we found there'd be varied specific data connected to a dmabuf, like
the iommu mapping of buffer, the dma descriptors (that can be shared
between several components). Though these info might be able to be
generated every time before dma operations, for performance sake,
it's better to be kept before really invalid.
Change-Id: I89d43dc3fe1ee3da91c42074da5df71b968e6d3c
Signed-off-by: Bin Wang binw@marvell.com
---
 drivers/base/dma-buf.c  |  100 +++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/dma-buf.h |   22 ++++++++++
 2 files changed, 122 insertions(+), 0 deletions(-)

diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
index 08fe897..5c82e60 100644
--- a/drivers/base/dma-buf.c
+++ b/drivers/base/dma-buf.c
@@ -50,6 +50,7 @@ static int dma_buf_release(struct inode *inode, struct file *file)
BUG_ON(dmabuf->vmapping_counter);
+	dma_buf_meta_release(dmabuf);
    dmabuf->ops->release(dmabuf);
mutex_lock(&db_list.lock);
@@ -138,6 +139,7 @@ struct dma_buf *dma_buf_export_named(void *priv, const struct dma_buf_ops *ops,
mutex_init(&dmabuf->lock);
    INIT_LIST_HEAD(&dmabuf->attachments);
+	INIT_LIST_HEAD(&dmabuf->metas);
mutex_lock(&db_list.lock);
    list_add(&dmabuf->list_node, &db_list.head);
@@ -570,6 +572,104 @@ void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)
 }
 EXPORT_SYMBOL_GPL(dma_buf_vunmap);
+/**
+ * dma_buf_meta_attach - Attach additional meta data to the dmabuf
+ * @dmabuf:	[in]	the dmabuf to attach to
+ * @id:		[in]	the id of the meta data
+ * @pdata:	[in]	the raw data to be attached
+ * @release:	[in]	the callback to release the meta data
+ */
+int dma_buf_meta_attach(struct dma_buf *dmabuf, int id, void *pdata,
+	int (*release)(void *))
+{
+	struct dma_buf_meta *pmeta;
+
+	pmeta = kmalloc(sizeof(struct dma_buf_meta), GFP_KERNEL);
+	if (pmeta == NULL)
+		return -ENOMEM;
+
+	pmeta->id = id;
+	pmeta->pdata = pdata;
+	pmeta->release = release;
+
+	mutex_lock(&dmabuf->lock);
+	list_add(&pmeta->node, &dmabuf->metas);
+	mutex_unlock(&dmabuf->lock);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(dma_buf_meta_attach);
+
+/**
+ * dma_buf_meta_dettach - Dettach the meta data from dmabuf by id
+ * @dmabuf:	[in]	the dmabuf including the meta data
+ * @id:		[in]	the id of the meta data
+ */
+int dma_buf_meta_dettach(struct dma_buf *dmabuf, int id)
+{
+	struct dma_buf_meta *pmeta, *tmp;
+	int ret = -ENOENT;
+
+	mutex_lock(&dmabuf->lock);
+	list_for_each_entry_safe(pmeta, tmp, &dmabuf->metas, node) {
+		if (pmeta->id == id) {
+			if (pmeta->release)
+				pmeta->release(pmeta->pdata);
+			list_del(&pmeta->node);
+			kfree(pmeta);
+			ret = 0;
+			break;
+		}
+	}
+	mutex_unlock(&dmabuf->lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(dma_buf_meta_dettach);
+
+/**
+ * dma_buf_meta_fetch - Get the meta data from dmabuf by id
+ * @dmabuf:	[in]	the dmabuf including the meta data
+ * @id:		[in]	the id of the meta data
+ */
+void *dma_buf_meta_fetch(struct dma_buf *dmabuf, int id)
+{
+	struct dma_buf_meta *pmeta;
+	void *pdata = NULL;
+
+	mutex_lock(&dmabuf->lock);
+	list_for_each_entry(pmeta, &dmabuf->metas, node) {
+		if (pmeta->id == id) {
+			pdata = pmeta->pdata;
+			break;
+		}
+	}
+	mutex_unlock(&dmabuf->lock);
+
+	return pdata;
+}
+EXPORT_SYMBOL_GPL(dma_buf_meta_fetch);
+
+/**
+ * dma_buf_meta_release - Release all the meta data attached to the dmabuf
+ * @dmabuf:	[in]	the dmabuf including the meta data
+ */
+void dma_buf_meta_release(struct dma_buf *dmabuf)
+{
+	struct dma_buf_meta *pmeta, *tmp;
+
+	mutex_lock(&dmabuf->lock);
+	list_for_each_entry_safe(pmeta, tmp, &dmabuf->metas, node) {
+		if (pmeta->release)
+			pmeta->release(pmeta->pdata);
+		list_del(&pmeta->node);
+		kfree(pmeta);
+	}
+	mutex_unlock(&dmabuf->lock);
+
+	return;
+}
+
 #ifdef CONFIG_DEBUG_FS
 static int dma_buf_describe(struct seq_file *s)
 {
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index dfac5ed..369d032 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -120,6 +120,7 @@ struct dma_buf {
    size_t size;
    struct file *file;
    struct list_head attachments;
+	struct list_head metas;
    const struct dma_buf_ops *ops;
    /* mutex to serialize list manipulation, attach/detach and vmap/unmap */
    struct mutex lock;
@@ -149,6 +150,20 @@ struct dma_buf_attachment {
 };
/**
+ * struct dma_buf_meta - holds varied meta data attached to the buffer
+ * @id: the identification of the meta data
+ * @dmabuf: buffer for this attachment.
+ * @node: list of dma_buf_meta.
+ * @pdata: specific meta data.
+ */
+struct dma_buf_meta {
+	int id;
+	struct list_head node;
+	int (*release)(void *pdata);
+	void *pdata;
+};
+
+/**
  * get_dma_buf - convenience wrapper for get_file.
  * @dmabuf:	[in]	pointer to dma_buf
  *
@@ -194,6 +209,13 @@ int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *,
    	 unsigned long);
 void *dma_buf_vmap(struct dma_buf *);
 void dma_buf_vunmap(struct dma_buf *, void *vaddr);
+
+int dma_buf_meta_attach(struct dma_buf *dmabuf, int id, void *pdata,
+	int (*release)(void *));
+int dma_buf_meta_dettach(struct dma_buf *dmabuf, int id);
+void *dma_buf_meta_fetch(struct dma_buf *dmabuf, int id);
+void dma_buf_meta_release(struct dma_buf *dmabuf);
+
 int dma_buf_debugfs_create_file(const char *name,
    			int (*write)(struct seq_file *));
 #endif /* __DMA_BUF_H__ */
-- 
1.7.0.4

    