|
| From: | Cédric Le Goater |
| Subject: | Re: [PATCH v4 10/25] migration: Add Error** argument to qemu_savevm_state_setup() |
| Date: | Mon, 11 Mar 2024 19:15:39 +0100 |
| User-agent: | Mozilla Thunderbird |
On 3/8/24 15:36, Fabiano Rosas wrote:
Cédric Le Goater <clg@redhat.com> writes:This prepares ground for the changes coming next which add an Error** argument to the .save_setup() handler. Callers of qemu_savevm_state_setup() now handle the error and fail earlier setting the migration state from MIGRATION_STATUS_SETUP to MIGRATION_STATUS_FAILED. In qemu_savevm_state(), move the cleanup to preserve the error reported by .save_setup() handlers. Since the previous behavior was to ignore errors at this step of migration, this change should be examined closely to check that cleanups are still correctly done. Signed-off-by: Cédric Le Goater <clg@redhat.com> --- Changes in v4:- Merged cleanup change in qemu_savevm_state() Changes in v3: - Set migration state to MIGRATION_STATUS_FAILED- Fixed error handling to be done under lock in bg_migration_thread() - Made sure an error is always set in case of failure in qemu_savevm_state_setup()migration/savevm.h | 2 +-migration/migration.c | 27 ++++++++++++++++++++++++--- migration/savevm.c | 26 +++++++++++++++----------- 3 files changed, 40 insertions(+), 15 deletions(-) diff --git a/migration/savevm.h b/migration/savevm.h index 74669733dd63a080b765866c703234a5c4939223..9ec96a995c93a42aad621595f0ed58596c532328 100644 --- a/migration/savevm.h +++ b/migration/savevm.h @@ -32,7 +32,7 @@ bool qemu_savevm_state_blocked(Error **errp); void qemu_savevm_non_migratable_list(strList **reasons); int qemu_savevm_state_prepare(Error **errp); -void qemu_savevm_state_setup(QEMUFile *f); +int qemu_savevm_state_setup(QEMUFile *f, Error **errp); bool qemu_savevm_state_guest_unplug_pending(void); int qemu_savevm_state_resume_prepare(MigrationState *s); void qemu_savevm_state_header(QEMUFile *f); diff --git a/migration/migration.c b/migration/migration.c index a49fcd53ee19df1ce0182bc99d7e064968f0317b..6d1544224e96f5edfe56939a9c8395d88ef29581 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -3408,6 +3408,8 @@ static void *migration_thread(void *opaque) int64_t setup_start = qemu_clock_get_ms(QEMU_CLOCK_HOST); MigThrError thr_error; bool urgent = false; + Error *local_err = NULL; + int ret;thread = migration_threads_add("live_migration", qemu_get_thread_id()); @@ -3451,9 +3453,17 @@ static void *migration_thread(void *opaque)}bql_lock();- qemu_savevm_state_setup(s->to_dst_file); + ret = qemu_savevm_state_setup(s->to_dst_file, &local_err); bql_unlock();+ if (ret) {+ migrate_set_error(s, local_err); + error_free(local_err); + migrate_set_state(&s->state, MIGRATION_STATUS_SETUP, + MIGRATION_STATUS_FAILED); + goto out; + } + qemu_savevm_wait_unplug(s, MIGRATION_STATUS_SETUP, MIGRATION_STATUS_ACTIVE);This^ should be before the new block it seems: GOOD: migrate_set_state new state setup migrate_set_state new state wait-unplug migrate_fd_cancel migrate_set_state new state cancelling migrate_fd_cleanup migrate_set_state new state cancelled migrate_fd_cancel ok 1 /x86_64/failover-virtio-net/migrate/abort/wait-unplug BAD: migrate_set_state new state setup migrate_fd_cancel migrate_set_state new state cancelling migrate_fd_cleanup migrate_set_state new state cancelled qemu-system-x86_64: ram_save_setup failed: Input/output error ** ERROR:../tests/qtest/virtio-net-failover.c:1203:test_migrate_abort_wait_unplug: assertion failed (status == "cancelling"): ("cancelled" == "cancelling") Otherwise migration_iteration_finish() will schedule the cleanup BH and that will run concurrently with migrate_fd_cancel() issued by the test and bad things happens.
This hack makes things work :
@@ -3452,6 +3452,9 @@ static void *migration_thread(void *opaq
qemu_savevm_send_colo_enable(s->to_dst_file);
}
+ qemu_savevm_wait_unplug(s, MIGRATION_STATUS_SETUP,
+ MIGRATION_STATUS_SETUP);
+
bql_lock();
ret = qemu_savevm_state_setup(s->to_dst_file, &local_err);
bql_unlock();
We should fix the test instead :) Unless waiting for failover devices
to unplug before the save_setup handlers and not after is ok.
commit c7e0acd5a3f8 ("migration: add new migration state wait-unplug")
is not clear about the justification.:
This patch adds a new migration state called wait-unplug. It is entered
after the SETUP state if failover devices are present. It will transition
into ACTIVE once all devices were succesfully unplugged from the guest.
===== PS: I guess the next level in our Freestyle Concurrency video-game is to make migrate_fd_cancel() stop setting state and poking files and only set a flag that's tested in the other parts of the code.
Is that a new item on the TODO list? Thanks, C.
@@ -3530,6 +3540,9 @@ static void *bg_migration_thread(void *opaque)MigThrError thr_error; QEMUFile *fb; bool early_fail = true; + bool setup_fail = true; + Error *local_err = NULL; + int ret;rcu_register_thread();object_ref(OBJECT(s)); @@ -3563,9 +3576,16 @@ static void *bg_migration_thread(void *opaque)bql_lock();qemu_savevm_state_header(s->to_dst_file); - qemu_savevm_state_setup(s->to_dst_file); + ret = qemu_savevm_state_setup(s->to_dst_file, &local_err); + if (ret) { + migrate_set_error(s, local_err); + error_free(local_err); + goto fail; + } bql_unlock();+ setup_fail = false;+ qemu_savevm_wait_unplug(s, MIGRATION_STATUS_SETUP, MIGRATION_STATUS_ACTIVE);@@ -3632,7 +3652,8 @@ static void *bg_migration_thread(void *opaque) fail:if (early_fail) { - migrate_set_state(&s->state, MIGRATION_STATUS_ACTIVE, + migrate_set_state(&s->state, + setup_fail ? MIGRATION_STATUS_SETUP : MIGRATION_STATUS_ACTIVE, MIGRATION_STATUS_FAILED); bql_unlock(); } diff --git a/migration/savevm.c b/migration/savevm.c index ee31ffb5e88cea723039c754c30ce2c8a0ef35f3..63fdbb5ad7d4dbfaef1d2094350bf302cc677602 100644 --- a/migration/savevm.c +++ b/migration/savevm.c @@ -1310,11 +1310,11 @@ int qemu_savevm_state_prepare(Error **errp) return 0; }-void qemu_savevm_state_setup(QEMUFile *f)+int qemu_savevm_state_setup(QEMUFile *f, Error **errp) { + ERRP_GUARD(); MigrationState *ms = migrate_get_current(); SaveStateEntry *se; - Error *local_err = NULL; int ret = 0;json_writer_int64(ms->vmdesc, "page_size", qemu_target_page_size());@@ -1323,10 +1323,9 @@ void qemu_savevm_state_setup(QEMUFile *f) trace_savevm_state_setup(); QTAILQ_FOREACH(se, &savevm_state.handlers, entry) { if (se->vmsd && se->vmsd->early_setup) { - ret = vmstate_save(f, se, ms->vmdesc, &local_err); + ret = vmstate_save(f, se, ms->vmdesc, errp); if (ret) { - migrate_set_error(ms, local_err); - error_report_err(local_err); + migrate_set_error(ms, *errp); qemu_file_set_error(f, ret); break; } @@ -1346,18 +1345,19 @@ void qemu_savevm_state_setup(QEMUFile *f) ret = se->ops->save_setup(f, se->opaque); save_section_footer(f, se); if (ret < 0) { + error_setg(errp, "failed to setup SaveStateEntry with id(name): " + "%d(%s): %d", se->section_id, se->idstr, ret); qemu_file_set_error(f, ret); break; } }if (ret) {- return; + return ret; }- if (precopy_notify(PRECOPY_NOTIFY_SETUP, &local_err)) {- error_report_err(local_err); - } + /* TODO: Should we check that errp is set in case of failure ? */ + return precopy_notify(PRECOPY_NOTIFY_SETUP, errp); }int qemu_savevm_state_resume_prepare(MigrationState *s)@@ -1728,7 +1728,10 @@ static int qemu_savevm_state(QEMUFile *f, Error **errp) ms->to_dst_file = f;qemu_savevm_state_header(f);- qemu_savevm_state_setup(f); + ret = qemu_savevm_state_setup(f, errp); + if (ret) { + goto cleanup; + }while (qemu_file_get_error(f) == 0) {if (qemu_savevm_state_iterate(f, false) > 0) { @@ -1741,10 +1744,11 @@ static int qemu_savevm_state(QEMUFile *f, Error **errp) qemu_savevm_state_complete_precopy(f, false, false); ret = qemu_file_get_error(f); } - qemu_savevm_state_cleanup(); if (ret != 0) { error_setg_errno(errp, -ret, "Error while writing VM state"); } +cleanup: + qemu_savevm_state_cleanup();if (ret != 0) {status = MIGRATION_STATUS_FAILED;
| [Prev in Thread] | Current Thread | [Next in Thread] |