[PATCH v5 1/6] liveupdate: Move file_set_ser handling to luo_session_serialize()

[Pasha Tatashin]

In preparation for allowing userspace to freeze a session explicitly
before kexec reboot, luo_file_freeze() and luo_file_unfreeze() need to
be called on session->file_set before any struct luo_session_ser entry
is reserved in luo_session_serialize().

Currently, struct luo_session_ser is populated and cleared across two
layers: luo_session_serialize() writes and clears ser->name, while
luo_file_freeze() and luo_file_unfreeze() write and clear
ser->file_set_ser.

Drop the struct luo_file_set_ser pointer parameter from
luo_file_freeze() and luo_file_unfreeze() (and struct luo_session_ser
from luo_session_freeze_one() and luo_session_unfreeze_one()), and
populate and clear all fields of struct luo_session_ser in
luo_session_serialize().

Signed-off-by: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
---
 kernel/liveupdate/luo_file.c     | 24 ++++++++----------------
 kernel/liveupdate/luo_internal.h |  6 ++----
 kernel/liveupdate/luo_session.c  | 19 ++++++++++---------
 3 files changed, 20 insertions(+), 29 deletions(-)

diff --git a/kernel/liveupdate/luo_file.c b/kernel/liveupdate/luo_file.c
index a39992da504f..988eb313a135 100644
--- a/kernel/liveupdate/luo_file.c
+++ b/kernel/liveupdate/luo_file.c
@@ -440,8 +440,7 @@ static void __luo_file_unfreeze(struct luo_file_set *file_set,
 
 /**
  * luo_file_freeze - Freezes all preserved files and serializes their metadata.
- * @file_set:     The file_set whose files are to be frozen.
- * @file_set_ser: Where to put the serialized file_set.
+ * @file_set: The file_set whose files are to be frozen.
  *
  * This function is called from the reboot() syscall path, just before the
  * kernel transitions to the new image via kexec. Its purpose is to perform the
@@ -457,8 +456,8 @@ static void __luo_file_unfreeze(struct luo_file_set *file_set,
  *
  * 2. Serializes Metadata: After a successful freeze, it copies the final file
  *    metadata—the handler's compatible string, the user token, and the final
- *    private data handle—into the pre-allocated contiguous memory buffer
- *    (file_set->files) that will be handed over to the next kernel via KHO.
+ *    private data handle—into the pre-allocated serialization blocks
+ *    (file_set->block_set) that will be handed over to the next kernel via KHO.
  *
  * Error Handling (Rollback):
  * This function is atomic. If any handler's .freeze() operation fails, the
@@ -471,8 +470,7 @@ static void __luo_file_unfreeze(struct luo_file_set *file_set,
  * Context: Called only from the liveupdate_reboot() path.
  * Return: 0 on success, or a negative errno on failure.
  */
-int luo_file_freeze(struct luo_file_set *file_set,
-		    struct luo_file_set_ser *file_set_ser)
+int luo_file_freeze(struct luo_file_set *file_set)
 {
 	struct luo_file *luo_file;
 	struct kho_block_set_it it;
@@ -506,9 +504,6 @@ int luo_file_freeze(struct luo_file_set *file_set,
 		file_ser->token = luo_file->token;
 	}
 
-	file_set_ser->count = file_set->count;
-	file_set_ser->files = kho_block_set_head_pa(&file_set->block_set);
-
 	return 0;
 
 err_unfreeze:
@@ -519,28 +514,25 @@ int luo_file_freeze(struct luo_file_set *file_set,
 
 /**
  * luo_file_unfreeze - Unfreezes all files in a file_set and clear serialization
- * @file_set:     The file_set whose files are to be unfrozen.
- * @file_set_ser: Serialized file_set.
+ * @file_set: The file_set whose files are to be unfrozen.
  *
  * This function rolls back the state of all files in a file_set after the
  * freeze phase has begun but must be aborted. It is the counterpart to
  * luo_file_freeze().
  *
  * It invokes the __luo_file_unfreeze() helper with a NULL argument, which
- * signals the helper to iterate through all files in the file_set and call
- * their respective .unfreeze() handler callbacks.
+ * signals the helper to iterate through all files in the file_set, call their
+ * respective .unfreeze() handler callbacks, and clear the serialized blocks.
  *
  * Context: This is called when the live update is aborted during
  *          the reboot() syscall, after luo_file_freeze() has been called.
  */
-void luo_file_unfreeze(struct luo_file_set *file_set,
-		       struct luo_file_set_ser *file_set_ser)
+void luo_file_unfreeze(struct luo_file_set *file_set)
 {
 	if (!file_set->count)
 		return;
 
 	__luo_file_unfreeze(file_set, NULL);
-	memset(file_set_ser, 0, sizeof(*file_set_ser));
 }
 
 /**
diff --git a/kernel/liveupdate/luo_internal.h b/kernel/liveupdate/luo_internal.h
index dac6644bfb18..01a172cd9d7a 100644
--- a/kernel/liveupdate/luo_internal.h
+++ b/kernel/liveupdate/luo_internal.h
@@ -103,10 +103,8 @@ int luo_session_deserialize(void);
 
 int luo_preserve_file(struct luo_file_set *file_set, u64 token, int fd);
 void luo_file_unpreserve_files(struct luo_file_set *file_set);
-int luo_file_freeze(struct luo_file_set *file_set,
-		    struct luo_file_set_ser *file_set_ser);
-void luo_file_unfreeze(struct luo_file_set *file_set,
-		       struct luo_file_set_ser *file_set_ser);
+int luo_file_freeze(struct luo_file_set *file_set);
+void luo_file_unfreeze(struct luo_file_set *file_set);
 int luo_retrieve_file(struct luo_file_set *file_set, u64 token,
 		      struct file **filep);
 int luo_file_finish(struct luo_file_set *file_set);
diff --git a/kernel/liveupdate/luo_session.c b/kernel/liveupdate/luo_session.c
index 74bc66929f4b..6dea35911181 100644
--- a/kernel/liveupdate/luo_session.c
+++ b/kernel/liveupdate/luo_session.c
@@ -219,18 +219,16 @@ static int luo_session_finish_one(struct luo_session *session)
 	return luo_file_finish(&session->file_set);
 }
 
-static void luo_session_unfreeze_one(struct luo_session *session,
-				     struct luo_session_ser *ser)
+static void luo_session_unfreeze_one(struct luo_session *session)
 {
 	guard(mutex)(&session->mutex);
-	luo_file_unfreeze(&session->file_set, &ser->file_set_ser);
+	luo_file_unfreeze(&session->file_set);
 }
 
-static int luo_session_freeze_one(struct luo_session *session,
-				  struct luo_session_ser *ser)
+static int luo_session_freeze_one(struct luo_session *session)
 {
 	guard(mutex)(&session->mutex);
-	return luo_file_freeze(&session->file_set, &ser->file_set_ser);
+	return luo_file_freeze(&session->file_set);
 }
 
 static int luo_session_release(struct inode *inodep, struct file *filep)
@@ -657,13 +655,16 @@ int luo_session_serialize(void)
 			goto err_undo;
 		}
 
-		err = luo_session_freeze_one(session, ser);
+		err = luo_session_freeze_one(session);
 		if (err) {
 			kho_block_set_it_prev(&it);
 			goto err_undo;
 		}
 
 		strscpy(ser->name, session->name, sizeof(ser->name));
+		ser->file_set_ser.count = session->file_set.count;
+		ser->file_set_ser.files =
+			kho_block_set_head_pa(&session->file_set.block_set);
 	}
 
 	if (sh->count > 0)
@@ -676,8 +677,8 @@ int luo_session_serialize(void)
 	list_for_each_entry_continue_reverse(session, &sh->list, list) {
 		struct luo_session_ser *ser = kho_block_set_it_prev(&it);
 
-		luo_session_unfreeze_one(session, ser);
-		memset(ser->name, 0, sizeof(ser->name));
+		luo_session_unfreeze_one(session);
+		memset(ser, 0, sizeof(*ser));
 	}
 	up_write(&sh->rwsem);
 	up_write(&luo_session_serialize_rwsem);
-- 
2.56.0.398.g882cbad275-goog