Expose the method docstring in the header, and mention
returned value must be free'd by caller.

Reported-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 include/sysemu/block-backend-io.h |  7 +++++++
 block/block-backend.c             | 12 ++++++++----
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/include/sysemu/block-backend-io.h b/include/sysemu/block-backend-io.h
index d174275a5c..ba8dfcc7d0 100644
--- a/include/sysemu/block-backend-io.h
+++ b/include/sysemu/block-backend-io.h
@@ -32,6 +32,13 @@ void blk_set_allow_aio_context_change(BlockBackend *blk, bool allow);
 void blk_set_disable_request_queuing(BlockBackend *blk, bool disable);
 bool blk_iostatus_is_enabled(const BlockBackend *blk);
 
+/*
+ * Return the qdev ID, or if no ID is assigned the QOM path,
+ * of the block device attached to the BlockBackend.
+ *
+ * The caller is responsible for releasing the value returned
+ * with g_free() after use.
+ */
 char *blk_get_attached_dev_id(BlockBackend *blk);
 
 BlockAIOCB *blk_aio_pwrite_zeroes(BlockBackend *blk, int64_t offset,
diff --git a/block/block-backend.c b/block/block-backend.c
index 85bcdedcef..7b329ff194 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -1019,6 +1019,10 @@ DeviceState *blk_get_attached_dev(BlockBackend *blk)
     return blk->dev;
 }
 
+/*
+ * The caller is responsible for releasing the value returned
+ * with g_free() after use.
+ */
 static char *blk_get_attached_dev_id_or_path(BlockBackend *blk, bool want_id)
 {
     DeviceState *dev = blk->dev;
@@ -1033,15 +1037,15 @@ static char *blk_get_attached_dev_id_or_path(BlockBackend *blk, bool want_id)
     return object_get_canonical_path(OBJECT(dev)) ?: g_strdup("");
 }
 
-/*
- * Return the qdev ID, or if no ID is assigned the QOM path, of the block
- * device attached to the BlockBackend.
- */
 char *blk_get_attached_dev_id(BlockBackend *blk)
 {
     return blk_get_attached_dev_id_or_path(blk, true);
 }
 
+/*
+ * The caller is responsible for releasing the value returned
+ * with g_free() after use.
+ */
 static char *blk_get_attached_dev_path(BlockBackend *blk)
 {
     return blk_get_attached_dev_id_or_path(blk, false);
-- 
2.45.2