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([2a01:e0a:280:24f0:9db0:474c:ff43:9f5c]) by smtp.gmail.com with ESMTPSA id kc2-20020a05622a44c200b0042ed9576bcesm2926273qtb.11.2024.03.11.11.15.40 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 11 Mar 2024 11:15:41 -0700 (PDT) Message-ID: <1566715b-a9a5-4df6-8e64-f4f912e2ea2f@redhat.com> Date: Mon, 11 Mar 2024 19:15:39 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 10/25] migration: Add Error** argument to qemu_savevm_state_setup() Content-Language: en-US, fr To: Fabiano Rosas , qemu-devel@nongnu.org Cc: Peter Xu , Alex Williamson , Avihai Horon , =?UTF-8?Q?Philippe_Mathieu-Daud=C3=A9?= , Markus Armbruster , Prasad Pandit References: <20240306133441.2351700-1-clg@redhat.com> <20240306133441.2351700-11-clg@redhat.com> <87plw44wps.fsf@suse.de> From: =?UTF-8?Q?C=C3=A9dric_Le_Goater?= In-Reply-To: <87plw44wps.fsf@suse.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=clg@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.029, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 3/8/24 15:36, Fabiano Rosas wrote: > Cédric Le Goater 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 >> --- >> >> 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; >