From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9ADDEC4332F for ; Wed, 23 Nov 2022 15:59:23 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oxs9T-0000pW-Ip; Wed, 23 Nov 2022 10:59:07 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oxs9P-0000mE-TH for qemu-devel@nongnu.org; Wed, 23 Nov 2022 10:59:03 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oxs9N-00089C-AV for qemu-devel@nongnu.org; Wed, 23 Nov 2022 10:59:03 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1669219140; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=yQXCgwUQ2ydLqdyzr7DpLLwk/ZoH+QHtysUU9GJpC+E=; b=J4z6rAeT1XcJ0o7NWRMxmcKeMhUWNfX8NPqcZgfRYBQR+aVcu43aUPCgAcDmJx9fX+Zyg+ wNmt3/OQm2u6ny0Qrrch7JETFNFo0JRRUflO3SRL1uY/6XmY11DL6Rg/n4s2yNU1Iu6Xly EagKcXDDVTkUQiuj8T2lBlZpD6RtZ6k= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-501-9Kf0zxegMa-t2bZRRFVY0Q-1; Wed, 23 Nov 2022 10:58:56 -0500 X-MC-Unique: 9Kf0zxegMa-t2bZRRFVY0Q-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 8ED531C07825; Wed, 23 Nov 2022 15:58:56 +0000 (UTC) Received: from redhat.com (unknown [10.33.36.56]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 32BEDC15BB1; Wed, 23 Nov 2022 15:58:55 +0000 (UTC) Date: Wed, 23 Nov 2022 15:58:50 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: "manish.mishra" Cc: qemu-devel@nongnu.org, peterx@redhat.com, prerna.saxena@nutanix.com, quintela@redhat.com, dgilbert@redhat.com, lsoaresp@redhat.com Subject: Re: [PATCH v4 2/2] migration: check magic value for deciding the mapping of channels Message-ID: References: <20221123150527.24608-1-manish.mishra@nutanix.com> <20221123150527.24608-3-manish.mishra@nutanix.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20221123150527.24608-3-manish.mishra@nutanix.com> User-Agent: Mutt/2.2.7 (2022-08-07) X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com 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, DKIMWL_WL_HIGH=-0.001, 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 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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Wed, Nov 23, 2022 at 03:05:27PM +0000, manish.mishra wrote: > Current logic assumes that channel connections on the destination side are > always established in the same order as the source and the first one will > always be the main channel followed by the multifid or post-copy > preemption channel. This may not be always true, as even if a channel has a > connection established on the source side it can be in the pending state on > the destination side and a newer connection can be established first. > Basically causing out of order mapping of channels on the destination side. > Currently, all channels except post-copy preempt send a magic number, this > patch uses that magic number to decide the type of channel. This logic is > applicable only for precopy(multifd) live migration, as mentioned, the > post-copy preempt channel does not send any magic number. Also, tls live > migrations already does tls handshake before creating other channels, so > this issue is not possible with tls, hence this logic is avoided for tls > live migrations. This patch uses read peek to check the magic number of > channels so that current data/control stream management remains > un-effected. > > Reviewed-by: Peter Xu > Reviewed-by: Daniel P. Berrangé Suggested-by: Daniel P. Berrangé Signed-off-by: manish.mishra > --- > migration/channel.c | 46 ++++++++++++++++++++++++++++++++++++++++ > migration/channel.h | 5 +++++ > migration/migration.c | 45 ++++++++++++++++++++++++++++----------- > migration/multifd.c | 12 ++++------- > migration/multifd.h | 2 +- > migration/postcopy-ram.c | 5 +---- > migration/postcopy-ram.h | 2 +- > 7 files changed, 91 insertions(+), 26 deletions(-) > > diff --git a/migration/channel.c b/migration/channel.c > index 1b0815039f..a4600f52c5 100644 > --- a/migration/channel.c > +++ b/migration/channel.c > @@ -92,3 +92,49 @@ void migration_channel_connect(MigrationState *s, > migrate_fd_connect(s, error); > error_free(error); > } > + > + > +/** > + * @migration_channel_read_peek - Read from the peek of migration channel, > + * without actually removing it from channel buffer. > + * > + * @ioc: the channel object > + * @buf: the memory region to read data into > + * @buflen: the number of bytes to read in @buf > + * @errp: pointer to a NULL-initialized error object > + * > + * Returns 0 if successful, returns -1 and sets @errp if fails. > + */ > +int migration_channel_read_peek(QIOChannel *ioc, > + const char *buf, > + const size_t buflen, > + Error **errp) > +{ > + ssize_t len = 0; > + struct iovec iov = { .iov_base = (char *)buf, .iov_len = buflen }; > + > + while (len < buflen) { > + len = qio_channel_readv_full(ioc, &iov, 1, NULL, > + NULL, QIO_CHANNEL_READ_FLAG_MSG_PEEK, errp); > + > + if (len == QIO_CHANNEL_ERR_BLOCK) { > + if (qemu_in_coroutine()) { > + /* 1ms sleep. */ > + qemu_co_sleep_ns(QEMU_CLOCK_REALTIME, 1000000); > + } else { > + qio_channel_wait(ioc, G_IO_IN); > + } > + continue; > + } > + if (len == 0) { > + error_setg(errp, > + "Unexpected end-of-file on channel"); > + return -1; > + } > + if (len < 0) { > + return -1; > + } > + } This busy waits when len > 0 and < buflen With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|