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([2a01:e0a:280:24f0:9db0:474c:ff43:9f5c]) by smtp.gmail.com with ESMTPSA id vv20-20020a05620a563400b0078908fe1764sm409125qkn.61.2024.03.12.07.01.11 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 12 Mar 2024 07:01:12 -0700 (PDT) Message-ID: Date: Tue, 12 Mar 2024 15:01:09 +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> <8ba5dba7-1849-46ff-b708-a9caac66be27@redhat.com> In-Reply-To: <8ba5dba7-1849-46ff-b708-a9caac66be27@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: -12 X-Spam_score: -1.3 X-Spam_bar: - X-Spam_report: (-1.3 / 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, RCVD_IN_SORBS_WEB=1.5, SPF_HELO_NONE=0.001, T_SCC_BODY_TEXT_LINE=-0.01, T_SPF_TEMPERROR=0.01 autolearn=no 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 14:34, Cédric Le Goater wrote: > 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. That works just the same. Peter, Fabiano, What would you prefer ? 1. move qemu_savevm_wait_unplug() before qemu_savevm_state_setup(), means one new patch. 2. leave qemu_savevm_wait_unplug() after qemu_savevm_state_setup() and handle state_setup() errors after waiting. means an update of this patch. Thanks, C.