1 files changed, 62 insertions, 3 deletions

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 3612ccededd6..ab96410d1dcd 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -48,8 +48,24 @@ struct dma_buf_list {
 
 static struct dma_buf_list db_list;
 
+static char *dmabuffs_dname(struct dentry *dentry, char *buffer, int buflen)
+{
+	struct dma_buf *dmabuf;
+	char name[DMA_BUF_NAME_LEN];
+	size_t ret = 0;
+
+	dmabuf = dentry->d_fsdata;
+	mutex_lock(&dmabuf->lock);
+	if (dmabuf->name)
+		ret = strlcpy(name, dmabuf->name, DMA_BUF_NAME_LEN);
+	mutex_unlock(&dmabuf->lock);
+
+	return dynamic_dname(dentry, buffer, buflen, "/%s:%s",
+			     dentry->d_name.name, ret > 0 ? name : "");
+}
+
 static const struct dentry_operations dma_buf_dentry_ops = {
-	.d_dname = simple_dname,
+	.d_dname = dmabuffs_dname,
 };
 
 static struct vfsmount *dma_buf_mnt;
@@ -301,6 +317,43 @@ out:
 	return events;
 }
 
+/**
+ * dma_buf_set_name - Set a name to a specific dma_buf to track the usage.
+ * The name of the dma-buf buffer can only be set when the dma-buf is not
+ * attached to any devices. It could theoritically support changing the
+ * name of the dma-buf if the same piece of memory is used for multiple
+ * purpose between different devices.
+ *
+ * @dmabuf [in]     dmabuf buffer that will be renamed.
+ * @buf:   [in]     A piece of userspace memory that contains the name of
+ *                  the dma-buf.
+ *
+ * Returns 0 on success. If the dma-buf buffer is already attached to
+ * devices, return -EBUSY.
+ *
+ */
+static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf)
+{
+	char *name = strndup_user(buf, DMA_BUF_NAME_LEN);
+	long ret = 0;
+
+	if (IS_ERR(name))
+		return PTR_ERR(name);
+
+	mutex_lock(&dmabuf->lock);
+	if (!list_empty(&dmabuf->attachments)) {
+		ret = -EBUSY;
+		kfree(name);
+		goto out_unlock;
+	}
+	kfree(dmabuf->name);
+	dmabuf->name = name;
+
+out_unlock:
+	mutex_unlock(&dmabuf->lock);
+	return ret;
+}
+
 static long dma_buf_ioctl(struct file *file,
 			  unsigned int cmd, unsigned long arg)
 {
@@ -339,6 +392,10 @@ static long dma_buf_ioctl(struct file *file,
 			ret = dma_buf_begin_cpu_access(dmabuf, direction);
 
 		return ret;
+
+	case DMA_BUF_SET_NAME:
+		return dma_buf_set_name(dmabuf, (const char __user *)arg);
+
 	default:
 		return -ENOTTY;
 	}
@@ -380,6 +437,7 @@ static struct file *dma_buf_getfile(struct dma_buf *dmabuf, int flags)
 		goto err_alloc_file;
 	file->f_flags = flags & (O_ACCMODE | O_NONBLOCK);
 	file->private_data = dmabuf;
+	file->f_path.dentry->d_fsdata = dmabuf;
 
 	return file;
 
@@ -1112,12 +1170,13 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
 			continue;
 		}
 
-		seq_printf(s, "%08zu\t%08x\t%08x\t%08ld\t%s\t%08lu\n",
+		seq_printf(s, "%08zu\t%08x\t%08x\t%08ld\t%s\t%08lu\t%s\n",
 				buf_obj->size,
 				buf_obj->file->f_flags, buf_obj->file->f_mode,
 				file_count(buf_obj->file),
 				buf_obj->exp_name,
-				file_inode(buf_obj->file)->i_ino);
+				file_inode(buf_obj->file)->i_ino,
+				buf_obj->name ?: "");
 
 		robj = buf_obj->resv;
 		while (true) {