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Tsirkin" , Thomas Huth , Jason Wang , Alex Williamson , Peter Xu Subject: [PULL 06/25] migration/multifd: Cleanup TLS iochannel referencing Date: Wed, 28 Feb 2024 13:12:56 +0800 Message-ID: <20240228051315.400759-7-peterx@redhat.com> In-Reply-To: <20240228051315.400759-1-peterx@redhat.com> References: <20240228051315.400759-1-peterx@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.7 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.129.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.088, 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_H2=-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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1709097465810100012 Content-Type: text/plain; charset="utf-8" From: Peter Xu Commit a1af605bd5 ("migration/multifd: fix hangup with TLS-Multifd due to blocking handshake") introduced a thread for TLS channels, which will resolve the issue on blocking the main thread. However in the same commit p->c is slightly abused just to be able to pass over the pointer "p" into the thread. That's the major reason we'll need to conditionally free the io channel in the fault paths. To clean it up, using a separate structure to pass over both "p" and "tioc" in the tls handshake thread. Then we can make it a rule that p->c will never be set until the channel is completely setup. With that, we can drop the tricky conditional unref of the io channel in the error path. Reviewed-by: Fabiano Rosas Link: https://lore.kernel.org/r/20240222095301.171137-2-peterx@redhat.com Signed-off-by: Peter Xu --- migration/multifd.c | 37 +++++++++++++++++++++++-------------- 1 file changed, 23 insertions(+), 14 deletions(-) diff --git a/migration/multifd.c b/migration/multifd.c index 43f0820996..84a6b9e58f 100644 --- a/migration/multifd.c +++ b/migration/multifd.c @@ -891,16 +891,22 @@ out: =20 static void multifd_new_send_channel_async(QIOTask *task, gpointer opaque); =20 +typedef struct { + MultiFDSendParams *p; + QIOChannelTLS *tioc; +} MultiFDTLSThreadArgs; + static void *multifd_tls_handshake_thread(void *opaque) { - MultiFDSendParams *p =3D opaque; - QIOChannelTLS *tioc =3D QIO_CHANNEL_TLS(p->c); + MultiFDTLSThreadArgs *args =3D opaque; =20 - qio_channel_tls_handshake(tioc, + qio_channel_tls_handshake(args->tioc, multifd_new_send_channel_async, - p, + args->p, NULL, NULL); + g_free(args); + return NULL; } =20 @@ -910,6 +916,7 @@ static bool multifd_tls_channel_connect(MultiFDSendPara= ms *p, { MigrationState *s =3D migrate_get_current(); const char *hostname =3D s->hostname; + MultiFDTLSThreadArgs *args; QIOChannelTLS *tioc; =20 tioc =3D migration_tls_client_create(ioc, hostname, errp); @@ -924,11 +931,14 @@ static bool multifd_tls_channel_connect(MultiFDSendPa= rams *p, object_unref(OBJECT(ioc)); trace_multifd_tls_outgoing_handshake_start(ioc, tioc, hostname); qio_channel_set_name(QIO_CHANNEL(tioc), "multifd-tls-outgoing"); - p->c =3D QIO_CHANNEL(tioc); + + args =3D g_new0(MultiFDTLSThreadArgs, 1); + args->tioc =3D tioc; + args->p =3D p; =20 p->tls_thread_created =3D true; qemu_thread_create(&p->tls_thread, "multifd-tls-handshake-worker", - multifd_tls_handshake_thread, p, + multifd_tls_handshake_thread, args, QEMU_THREAD_JOINABLE); return true; } @@ -941,6 +951,7 @@ static bool multifd_channel_connect(MultiFDSendParams *= p, =20 migration_ioc_register_yank(ioc); p->registered_yank =3D true; + /* Setup p->c only if the channel is completely setup */ p->c =3D ioc; =20 p->thread_created =3D true; @@ -994,14 +1005,12 @@ out: =20 trace_multifd_new_send_channel_async_error(p->id, local_err); multifd_send_set_error(local_err); - if (!p->c) { - /* - * If no channel has been created, drop the initial - * reference. Otherwise cleanup happens at - * multifd_send_channel_destroy() - */ - object_unref(OBJECT(ioc)); - } + /* + * For error cases (TLS or non-TLS), IO channel is always freed here + * rather than when cleanup multifd: since p->c is not set, multifd + * cleanup code doesn't even know its existence. + */ + object_unref(OBJECT(ioc)); error_free(local_err); } =20 --=20 2.43.0