From c8a7fc5179c649eed1d4286776a23e8a1a183cdc Mon Sep 17 00:00:00 2001 From: Steve Sistare Date: Wed, 18 Oct 2023 06:03:36 -0700 Subject: migration: simplify blockers Modify migrate_add_blocker and migrate_del_blocker to take an Error ** reason. This allows migration to own the Error object, so that if an error occurs in migrate_add_blocker, migration code can free the Error and clear the client handle, simplifying client code. It also simplifies the migrate_del_blocker call site. In addition, this is a pre-requisite for a proposed future patch that would add a mode argument to migration requests to support live update, and maintain a list of blockers for each mode. A blocker may apply to a single mode or to multiple modes, and passing Error** will allow one Error object to be registered for multiple modes. No functional change. Signed-off-by: Steve Sistare Tested-by: Michael Galaxy Reviewed-by: Michael Galaxy Reviewed-by: Peter Xu Reviewed-by: Juan Quintela Signed-off-by: Juan Quintela Message-ID: <1697634216-84215-1-git-send-email-steven.sistare@oracle.com> --- include/migration/blocker.h | 24 +++++++++++++++++------- 1 file changed, 17 insertions(+), 7 deletions(-) (limited to 'include') diff --git a/include/migration/blocker.h b/include/migration/blocker.h index 9cebe2b..b048f30 100644 --- a/include/migration/blocker.h +++ b/include/migration/blocker.h @@ -17,19 +17,23 @@ /** * @migrate_add_blocker - prevent migration from proceeding * - * @reason - an error to be returned whenever migration is attempted + * @reasonp - address of an error to be returned whenever migration is attempted * * @errp - [out] The reason (if any) we cannot block migration right now. * * @returns - 0 on success, -EBUSY/-EACCES on failure, with errp set. + * + * *@reasonp is freed and set to NULL if failure is returned. + * On success, the caller must not free @reasonp, except by + * calling migrate_del_blocker. */ -int migrate_add_blocker(Error *reason, Error **errp); +int migrate_add_blocker(Error **reasonp, Error **errp); /** * @migrate_add_blocker_internal - prevent migration from proceeding without * only-migrate implications * - * @reason - an error to be returned whenever migration is attempted + * @reasonp - address of an error to be returned whenever migration is attempted * * @errp - [out] The reason (if any) we cannot block migration right now. * @@ -38,14 +42,20 @@ int migrate_add_blocker(Error *reason, Error **errp); * Some of the migration blockers can be temporary (e.g., for a few seconds), * so it shouldn't need to conflict with "-only-migratable". For those cases, * we can call this function rather than @migrate_add_blocker(). + * + * *@reasonp is freed and set to NULL if failure is returned. + * On success, the caller must not free @reasonp, except by + * calling migrate_del_blocker. */ -int migrate_add_blocker_internal(Error *reason, Error **errp); +int migrate_add_blocker_internal(Error **reasonp, Error **errp); /** - * @migrate_del_blocker - remove a blocking error from migration + * @migrate_del_blocker - remove a blocking error from migration and free it. + * + * @reasonp - address of the error blocking migration * - * @reason - the error blocking migration + * This function frees *@reasonp and sets it to NULL. */ -void migrate_del_blocker(Error *reason); +void migrate_del_blocker(Error **reasonp); #endif -- cgit v1.1