On Sat, Nov 15, 2025 at 06:33:53PM -0500, Pasha Tatashin wrote:

Introducing the userspace interface and internal logic required to
manage the lifecycle of file descriptors within a session. Previously, a
session was merely a container; this change makes it a functional
management unit.

The following capabilities are added:

A new set of ioctl commands are added, which operate on the file
descriptor returned by CREATE_SESSION. This allows userspace to:
- LIVEUPDATE_SESSION_PRESERVE_FD: Add a file descriptor to a session
  to be preserved across the live update.
- LIVEUPDATE_SESSION_RETRIEVE_FD: Retrieve a preserved file in the
  new kernel using its unique token.
- LIVEUPDATE_SESSION_FINISH: finish session

The session's .release handler is enhanced to be state-aware. When a
session's file descriptor is closed, it correctly unpreserves
the session based on its current state before freeing all
associated file resources.

Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
---
 include/uapi/linux/liveupdate.h | 103 ++++++++++++++++++
 kernel/liveupdate/luo_session.c | 187 +++++++++++++++++++++++++++++++-
 2 files changed, 286 insertions(+), 4 deletions(-)

...

 static int luo_session_release(struct inode *inodep, struct file *filep)
 {
 	struct luo_session *session = filep->private_data;
 	struct luo_session_header *sh;
+	int err = 0;
 
 	/* If retrieved is set, it means this session is from incoming list */
-	if (session->retrieved)
+	if (session->retrieved) {
 		sh = &luo_session_global.incoming;
-	else
+
+		err = luo_session_finish_one(session);
+		if (err) {
+			pr_warn("Unable to finish session [%s] on release\n",
+				session->name);

			return err;

and then else can go away here and luo_session_remove() and
luo_session_free() can be moved outside if (session->retrieved).

+		} else {
+			luo_session_remove(sh, session);
+			luo_session_free(session);
+		}
+
+	} else {
 		sh = &luo_session_global.outgoing;
 
-	luo_session_remove(sh, session);
-	luo_session_free(session);
+		scoped_guard(mutex, &session->mutex)
+			luo_file_unpreserve_files(session);
+		luo_session_remove(sh, session);
+		luo_session_free(session);
+	}
+
+	return err;
+}

-- 
Sincerely yours,
Mike.