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([2a01:e0a:280:24f0:9db0:474c:ff43:9f5c]) by smtp.gmail.com with ESMTPSA id m15-20020a05600c3b0f00b00413218ca719sm11712441wms.4.2024.03.12.06.34.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 12 Mar 2024 06:34:23 -0700 (PDT) Message-ID: <8ba5dba7-1849-46ff-b708-a9caac66be27@redhat.com> Date: Tue, 12 Mar 2024 14:34:21 +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 From: =?UTF-8?Q?C=C3=A9dric_Le_Goater?= 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> <1566715b-a9a5-4df6-8e64-f4f912e2ea2f@redhat.com> <87le6omw0d.fsf@suse.de> <9071affc-ffb5-435a-99d1-ca829703e31b@redhat.com> In-Reply-To: <9071affc-ffb5-435a-99d1-ca829703e31b@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.129.124; envelope-from=clg@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.687, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, 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 3/12/24 13:32, Cédric Le Goater wrote: > On 3/11/24 20:03, Fabiano Rosas wrote: >> Cédric Le Goater writes: >> >>> 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); >>> + >> >> Why move it all the way up here? Has moving the wait_unplug before the >> 'if (ret)' block not worked for you? > > We could be sleeping while holding the BQL. It looked wrong. Sorry wrong answer. Yes I can try moving it before the 'if (ret)' block. I can reproduce easily with an x86 guest running on PPC64. Thanks, C.