From fa3673e497a1119fbf2c1f948da71907a84385d9 Mon Sep 17 00:00:00 2001 From: Steve Sistare Date: Wed, 25 Oct 2023 12:44:25 -0700 Subject: [PATCH] migration: per-mode blockers Extend the blocker interface so that a blocker can be registered for one or more migration modes. The existing interfaces register a blocker for all modes, and the new interfaces take a varargs list of modes. Internally, maintain a separate blocker list per mode. The same Error object may be added to multiple lists. When a block is deleted, it is removed from every list, and the Error is freed. No functional change until a new mode is added. Signed-off-by: Steve Sistare Reviewed-by: Juan Quintela Signed-off-by: Juan Quintela Message-ID: <1698263069-406971-3-git-send-email-steven.sistare@oracle.com> --- include/migration/blocker.h | 44 +++++++++++++++++++-- migration/migration.c | 95 ++++++++++++++++++++++++++++++++++++++------- stubs/migr-blocker.c | 10 +++++ 3 files changed, 132 insertions(+), 17 deletions(-) diff --git a/include/migration/blocker.h b/include/migration/blocker.h index b048f301b4..a687ac0efe 100644 --- a/include/migration/blocker.h +++ b/include/migration/blocker.h @@ -14,8 +14,12 @@ #ifndef MIGRATION_BLOCKER_H #define MIGRATION_BLOCKER_H +#include "qapi/qapi-types-migration.h" + +#define MIG_MODE_ALL MIG_MODE__MAX + /** - * @migrate_add_blocker - prevent migration from proceeding + * @migrate_add_blocker - prevent all modes of migration from proceeding * * @reasonp - address of an error to be returned whenever migration is attempted * @@ -30,8 +34,8 @@ int migrate_add_blocker(Error **reasonp, Error **errp); /** - * @migrate_add_blocker_internal - prevent migration from proceeding without - * only-migrate implications + * @migrate_add_blocker_internal - prevent all modes of migration from + * proceeding, but ignore -only-migratable * * @reasonp - address of an error to be returned whenever migration is attempted * @@ -50,7 +54,7 @@ int migrate_add_blocker(Error **reasonp, Error **errp); int migrate_add_blocker_internal(Error **reasonp, Error **errp); /** - * @migrate_del_blocker - remove a blocking error from migration and free it. + * @migrate_del_blocker - remove a migration blocker from all modes and free it. * * @reasonp - address of the error blocking migration * @@ -58,4 +62,36 @@ int migrate_add_blocker_internal(Error **reasonp, Error **errp); */ void migrate_del_blocker(Error **reasonp); +/** + * @migrate_add_blocker_normal - prevent normal migration mode from proceeding + * + * @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_normal(Error **reasonp, Error **errp); + +/** + * @migrate_add_blocker_modes - prevent some modes of migration from proceeding + * + * @reasonp - address of an error to be returned whenever migration is attempted + * + * @errp - [out] The reason (if any) we cannot block migration right now. + * + * @mode - one or more migration modes to be blocked. The list is terminated + * by -1 or MIG_MODE_ALL. For the latter, all modes are blocked. + * + * @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 before the blocker is removed. + */ +int migrate_add_blocker_modes(Error **reasonp, Error **errp, MigMode mode, ...); + #endif diff --git a/migration/migration.c b/migration/migration.c index c334b9effd..11c1490090 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -92,7 +92,7 @@ enum mig_rp_message_type { static MigrationState *current_migration; static MigrationIncomingState *current_incoming; -static GSList *migration_blockers; +static GSList *migration_blockers[MIG_MODE__MAX]; static bool migration_object_check(MigrationState *ms, Error **errp); static int migration_maybe_pause(MigrationState *s, @@ -1043,7 +1043,7 @@ static void fill_source_migration_info(MigrationInfo *info) { MigrationState *s = migrate_get_current(); int state = qatomic_read(&s->state); - GSList *cur_blocker = migration_blockers; + GSList *cur_blocker = migration_blockers[migrate_mode()]; info->blocked_reasons = NULL; @@ -1507,38 +1507,105 @@ int migrate_init(MigrationState *s, Error **errp) return 0; } -int migrate_add_blocker_internal(Error **reasonp, Error **errp) +static bool is_busy(Error **reasonp, Error **errp) { + ERRP_GUARD(); + /* Snapshots are similar to migrations, so check RUN_STATE_SAVE_VM too. */ if (runstate_check(RUN_STATE_SAVE_VM) || !migration_is_idle()) { error_propagate_prepend(errp, *reasonp, "disallowing migration blocker " "(migration/snapshot in progress) for: "); *reasonp = NULL; - return -EBUSY; + return true; } - - migration_blockers = g_slist_prepend(migration_blockers, *reasonp); - return 0; + return false; } -int migrate_add_blocker(Error **reasonp, Error **errp) +static bool is_only_migratable(Error **reasonp, Error **errp, int modes) { - if (only_migratable) { + ERRP_GUARD(); + + if (only_migratable && (modes & BIT(MIG_MODE_NORMAL))) { error_propagate_prepend(errp, *reasonp, "disallowing migration blocker " "(--only-migratable) for: "); *reasonp = NULL; + return true; + } + return false; +} + +static int get_modes(MigMode mode, va_list ap) +{ + int modes = 0; + + while (mode != -1 && mode != MIG_MODE_ALL) { + assert(mode >= MIG_MODE_NORMAL && mode < MIG_MODE__MAX); + modes |= BIT(mode); + mode = va_arg(ap, MigMode); + } + if (mode == MIG_MODE_ALL) { + modes = BIT(MIG_MODE__MAX) - 1; + } + return modes; +} + +static int add_blockers(Error **reasonp, Error **errp, int modes) +{ + for (MigMode mode = 0; mode < MIG_MODE__MAX; mode++) { + if (modes & BIT(mode)) { + migration_blockers[mode] = g_slist_prepend(migration_blockers[mode], + *reasonp); + } + } + return 0; +} + +int migrate_add_blocker(Error **reasonp, Error **errp) +{ + return migrate_add_blocker_modes(reasonp, errp, MIG_MODE_ALL); +} + +int migrate_add_blocker_normal(Error **reasonp, Error **errp) +{ + return migrate_add_blocker_modes(reasonp, errp, MIG_MODE_NORMAL, -1); +} + +int migrate_add_blocker_modes(Error **reasonp, Error **errp, MigMode mode, ...) +{ + int modes; + va_list ap; + + va_start(ap, mode); + modes = get_modes(mode, ap); + va_end(ap); + + if (is_only_migratable(reasonp, errp, modes)) { return -EACCES; + } else if (is_busy(reasonp, errp)) { + return -EBUSY; } + return add_blockers(reasonp, errp, modes); +} - return migrate_add_blocker_internal(reasonp, errp); +int migrate_add_blocker_internal(Error **reasonp, Error **errp) +{ + int modes = BIT(MIG_MODE__MAX) - 1; + + if (is_busy(reasonp, errp)) { + return -EBUSY; + } + return add_blockers(reasonp, errp, modes); } void migrate_del_blocker(Error **reasonp) { if (*reasonp) { - migration_blockers = g_slist_remove(migration_blockers, *reasonp); + for (MigMode mode = 0; mode < MIG_MODE__MAX; mode++) { + migration_blockers[mode] = g_slist_remove(migration_blockers[mode], + *reasonp); + } error_free(*reasonp); *reasonp = NULL; } @@ -1634,12 +1701,14 @@ void qmp_migrate_pause(Error **errp) bool migration_is_blocked(Error **errp) { + GSList *blockers = migration_blockers[migrate_mode()]; + if (qemu_savevm_state_blocked(errp)) { return true; } - if (migration_blockers) { - error_propagate(errp, error_copy(migration_blockers->data)); + if (blockers) { + error_propagate(errp, error_copy(blockers->data)); return true; } diff --git a/stubs/migr-blocker.c b/stubs/migr-blocker.c index 17a5dbf87b..11cbff268f 100644 --- a/stubs/migr-blocker.c +++ b/stubs/migr-blocker.c @@ -6,6 +6,16 @@ int migrate_add_blocker(Error **reasonp, Error **errp) return 0; } +int migrate_add_blocker_normal(Error **reasonp, Error **errp) +{ + return 0; +} + +int migrate_add_blocker_modes(Error **reasonp, Error **errp, MigMode mode, ...) +{ + return 0; +} + void migrate_del_blocker(Error **reasonp) { } -- 2.11.0