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Thu, 18 Sep 2025 13:43:22 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id 8n/tAHoMzGgMNQAAD6G6ig (envelope-from ); Thu, 18 Sep 2025 13:43:22 +0000 From: Fabiano Rosas To: Peter Xu Cc: qemu-devel@nongnu.org, Juraj Marcin , =?utf-8?Q?Da?= =?utf-8?Q?niel_P_=2E_Berrang=C3=A9?= Subject: Re: [PATCH 2/3] migration: Make migration_has_failed() work even for CANCELLING In-Reply-To: References: <20250910160144.1762894-1-peterx@redhat.com> <20250910160144.1762894-3-peterx@redhat.com> <87wm5wvm1l.fsf@suse.de> Date: Thu, 18 Sep 2025 10:43:19 -0300 Message-ID: <87ldmbvpu0.fsf@suse.de> MIME-Version: 1.0 Content-Type: text/plain X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; ARC_NA(0.00)[]; MISSING_XM_UA(0.00)[]; RCVD_TLS_ALL(0.00)[]; MIME_TRACE(0.00)[0:+]; RCVD_VIA_SMTP_AUTH(0.00)[]; TO_DN_SOME(0.00)[]; FUZZY_RATELIMITED(0.00)[rspamd.com]; MID_RHS_MATCH_FROM(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_THREE(0.00)[4]; FROM_EQ_ENVFROM(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:mid] Received-SPF: pass client-ip=2a07:de40:b251:101:10:150:64:1; envelope-from=farosas@suse.de; helo=smtp-out1.suse.de X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 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 Peter Xu writes: > On Wed, Sep 17, 2025 at 05:52:54PM -0300, Fabiano Rosas wrote: >> Peter Xu writes: >> >> > We set CANCELLED very late, it means migration_has_failed() may not work >> > correctly if it's invoked before updating CANCELLING to CANCELLED. >> > >> >> The prophecy is fulfilled. >> >> https://wiki.qemu.org/ToDo/LiveMigration#Migration_cancel_concurrency >> >> I'm not sure I'm convinced, for instance, CANCELLING is part of >> migration_is_running(), while FAILED is not. This doesn't seem >> right. Another point is that CANCELLING is not a final state, so we're >> prone to later need a migration_has_finished_failing_now() helper. =) > > Considering we only have two users so far, and the other user doesn't care > about CANCELLING (while the multifd shutdown cares?), then I assume it's ok > to treat CANCELLING to be "has failed"? :) I didn't try to interpret "has > failed" in English, but only for the sake of an universal helper that works > for both places. > > Or maybe it can be is_failing() too? I don't have a strong feeling. > I'm not nitipicking on language. I'm pointing out that CANCELLING is a transitory state, i.e. from migrate_cancel() until migrate_cleanup(), while FAILED is a terminal state, nothing happens after it. But fine, I guess it's really only *my* assumptions being broken and not the ones in the code. >> >> My mental model is that CANCELLING is a transitional, ongoing state >> where we shouldn't really be making assumptions. Once FAILED is reached, >> then we're sure in which general state everything is. >> >> How did you catch this? It was one of the cancel tests that failed? I >> just noticed that multifd_send_shutdown() is called from >> migration_cleanup() before it changes the state to CANCELLED. So current >> code also has whatever issue you detected here. > > No test failed, it was only by code observation, mentioned below [1], > exactly as you said. > > I just think when cancelling the tls sessions, we shouldn't dump the error > messages anymore even if the bye failed. Ok > Or maybe we simply do not need to > invoke migration_tls_channel_end() when CANCELLING / FAILED? That's > relevant to your ask on the cover letter, we can discuss there. > > This is very trivial. Nah, let me review the patch properly, please. > Let me know how you thinks. I can also drop this > patch when repost v3 but fix the postcopy warning first, which reliably > reproduce now with qtest. > >> >> > Allow that state will make migration_has_failed() working as expected even >> > if it's invoked slightly earlier. >> > >> > One current user is the multifd code for the TLS graceful termination, >> > where it's before updating to CANCELLED. > > [1] > >> > >> > Signed-off-by: Peter Xu >> > --- >> > migration/migration.c | 3 ++- >> > 1 file changed, 2 insertions(+), 1 deletion(-) >> > >> > diff --git a/migration/migration.c b/migration/migration.c >> > index 7015c2b5e0..397917b1b3 100644 >> > --- a/migration/migration.c >> > +++ b/migration/migration.c >> > @@ -1723,7 +1723,8 @@ int migration_call_notifiers(MigrationState *s, MigrationEventType type, >> > >> > bool migration_has_failed(MigrationState *s) >> > { >> > - return (s->state == MIGRATION_STATUS_CANCELLED || >> > + return (s->state == MIGRATION_STATUS_CANCELLING || >> > + s->state == MIGRATION_STATUS_CANCELLED || >> > s->state == MIGRATION_STATUS_FAILED); >> > } >>