[PATCH V15 13/14] iothread: make legacy AioContext getter explicitly unsafe

[Zhang Chen <zhangckid@gmail.com>]

Now that holder-aware callers have been converted, rename
iothread_get_aio_context() to iothread_unsafe_get_aio_context() and
update qmp_x_blockdev_set_iothread(). This avoids adding a duplicate
accessor only to remove the old one later.

The block graph retains only the AioContext, while detachment happens
outside qmp_x_blockdev_set_iothread(), so this call site cannot provide
a matching holder lifecycle. The new name makes its existing lifetime
assumption explicit.

New code should use iothread_ref_and_get_aio_context().

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Zhang Chen <zhangckid@gmail.com>
---
 blockdev.c                |  7 ++++++-
 include/system/iothread.h | 11 ++++++++++-
 iothread.c                |  2 +-
 3 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/blockdev.c b/blockdev.c
index 6e86c6262f..97d161079a 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3683,7 +3683,12 @@ void qmp_x_blockdev_set_iothread(const char *node_name, StrOrNull *iothread,
             goto out;
         }
 
-        new_context = iothread_get_aio_context(obj);
+        /*
+         * The block graph retains only the AioContext, not the IOThread.
+         * Context detachment happens outside this command, so there is no
+         * point here where a matching IOThread holder can be released.
+         */
+        new_context = iothread_unsafe_get_aio_context(obj);
     } else {
         new_context = qemu_get_aio_context();
     }
diff --git a/include/system/iothread.h b/include/system/iothread.h
index f6c5f95dd9..9850cdb3dc 100644
--- a/include/system/iothread.h
+++ b/include/system/iothread.h
@@ -66,7 +66,16 @@ DECLARE_INSTANCE_CHECKER(IOThread, IOTHREAD,
 
 char *iothread_get_id(IOThread *iothread);
 IOThread *iothread_by_id(const char *id);
-AioContext *iothread_get_aio_context(IOThread *iothread);
+
+/*
+ * Return @iothread's AioContext without registering a holder or taking a
+ * reference on @iothread.  The caller must ensure that the IOThread remains
+ * alive for as long as the returned AioContext is used.
+ *
+ * This API exists for legacy callers without a clear ref/unref lifecycle.  Do
+ * not use it in new code; use iothread_ref_and_get_aio_context() instead.
+ */
+AioContext *iothread_unsafe_get_aio_context(IOThread *iothread);
 
 /*
  * Register @holder and return @iothread's AioContext.  The holder is copied,
diff --git a/iothread.c b/iothread.c
index 58dace351c..ae9290c733 100644
--- a/iothread.c
+++ b/iothread.c
@@ -422,7 +422,7 @@ char *iothread_get_id(IOThread *iothread)
     return g_strdup(object_get_canonical_path_component(OBJECT(iothread)));
 }
 
-AioContext *iothread_get_aio_context(IOThread *iothread)
+AioContext *iothread_unsafe_get_aio_context(IOThread *iothread)
 {
     return iothread->ctx;
 }
-- 
2.43.0