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 97046C433EF for ; Wed, 15 Jun 2022 11:59:07 +0000 (UTC) Received: from localhost ([::1]:59590 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1o1Rfu-0008VH-A9 for qemu-devel@archiver.kernel.org; Wed, 15 Jun 2022 07:59:06 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:45868) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1o1Rdb-0006KJ-Kq for qemu-devel@nongnu.org; Wed, 15 Jun 2022 07:56:43 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:26807) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1o1RdY-0008HF-Ow for qemu-devel@nongnu.org; Wed, 15 Jun 2022 07:56:42 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1655294199; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Cevr6JF9r/CfQw0fSstk79f0mOEbJkFoPNoRRG7APM8=; b=KsbmHeaTpTNE8mslCNeTZxqoZYJXC/4YJRQnheOj58NhHi2khI4Tb92NImVHkEMAvXotv1 MSaI+ckNjn/tYHpQRuZ4i6FyOgL/OBHXLvBB07El+5qw4UpdBZvIOQW4IxhKUH3kwlcvDm tHTvkjcDErzKKgd/CCige3vEE3glzd0= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-457-RM6NEkqhMZOBpCmXdLLDaw-1; Wed, 15 Jun 2022 07:56:38 -0400 X-MC-Unique: RM6NEkqhMZOBpCmXdLLDaw-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 3536880159B for ; Wed, 15 Jun 2022 11:56:38 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.39.195.112]) by smtp.corp.redhat.com (Postfix) with ESMTPS id EA3CC2026D64; Wed, 15 Jun 2022 11:56:37 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 9064B21E59D1; Wed, 15 Jun 2022 13:56:36 +0200 (CEST) From: Markus Armbruster To: Laurent Vivier Cc: qemu-devel@nongnu.org, Jason Wang , Thomas Huth Subject: Re: [RFC PATCH v2 2/8] qapi: net: introduce a way to bypass qemu_opts_parse_noisily() References: <20220512080932.735962-1-lvivier@redhat.com> <20220512080932.735962-3-lvivier@redhat.com> <87v8u91xwd.fsf@pond.sub.org> <81563e7d-7743-beab-6eaa-3bb20be1b0df@redhat.com> Date: Wed, 15 Jun 2022 13:56:36 +0200 In-Reply-To: <81563e7d-7743-beab-6eaa-3bb20be1b0df@redhat.com> (Laurent Vivier's message of "Thu, 9 Jun 2022 22:52:37 +0200") Message-ID: <87a6aegmx7.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 Received-SPF: pass client-ip=170.10.129.124; envelope-from=armbru@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=-0.082, 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" Laurent Vivier writes: > On 13/05/2022 13:21, Markus Armbruster wrote: >> Laurent Vivier writes: >> >>> As qemu_opts_parse_noisily() flattens the QAPI structures ("type" field >>> of Netdev structure can collides with "type" field of SocketAddress), >> >> To remember how this works, I have to write a more verbose version of >> the above. Why not post it then, so here goes. >> >> qemu_init() passes the argument of -netdev, -nic, and -net to >> net_client_parse(). >> >> net_client_parse() parses with qemu_opts_parse_noisily(), passing >> QemuOptsList qemu_netdev_opts for -netdev, qemu_nic_opts for -nic, and >> qemu_net_opts for -net. Their desc[] are all empty, which means any >> keys are accepted. The result of the parse (a QemuOpts) is stored in >> the QemuOptsList. >> >> Note that QemuOpts is flat by design. In some places, we layer non-flat >> on top using dotted keys convention, but not here. >> >> net_init_clients() iterates over the stored QemuOpts, and passes them to >> net_init_netdev(), net_param_nic(), or net_init_client(), respectively. >> >> These functions pass the QemuOpts to net_client_init(). They also do >> other things with the QemuOpts, which we can ignore here. >> >> net_client_init() uses the opts visitor to convert the (flat) QemOpts to >> a (non-flat) QAPI object Netdev. Netdev is also the argument of QMP >> command netdev_add. >> >> The opts visitor was an early attempt to support QAPI in >> (QemuOpts-based) CLI. It restricts QAPI types to a certain shape; see >> commit eb7ee2cbeb "qapi: introduce OptsVisitor". >> >> A more modern way to support QAPI is qobject_input_visitor_new_str(). >> It uses keyval_parse() instead of QemuOpts for KEY=VALUE,... syntax, and >> it also supports JSON syntax. The former isn't quite as expressive as >> JSON, but it's a lot closer than QemuOpts + opts visitor. >> >>> we introduce a way to bypass qemu_opts_parse_noisily() and use directly >>> visit_type_Netdev() to parse the backend parameters. >> >> This commit paves the way to use of the modern way instead. > > I'm going to copy your analysis to the commit message of the patch. Go right ahead :) >>> Signed-off-by: Laurent Vivier >>> --- >>> net/net.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ >>> 1 file changed, 54 insertions(+) >>> >>> diff --git a/net/net.c b/net/net.c >>> index 58c05c200622..2aab7167316c 100644 >>> --- a/net/net.c >>> +++ b/net/net.c >>> @@ -54,6 +54,7 @@ >>> #include "net/colo-compare.h" >>> #include "net/filter.h" >>> #include "qapi/string-output-visitor.h" >>> +#include "qapi/qobject-input-visitor.h" >>> >>> /* Net bridge is currently not supported for W32. */ >>> #if !defined(_WIN32) >>> @@ -63,6 +64,17 @@ >>> static VMChangeStateEntry *net_change_state_entry; >>> static QTAILQ_HEAD(, NetClientState) net_clients; >>> >>> +typedef struct NetdevQueueEntry { >>> + bool is_netdev; >>> + Netdev *nd; >>> + Location loc; >>> + QSIMPLEQ_ENTRY(NetdevQueueEntry) entry; >>> +} NetdevQueueEntry; >>> + >>> +typedef QSIMPLEQ_HEAD(, NetdevQueueEntry) NetdevQueue; >>> + >>> +static NetdevQueue nd_queue = QSIMPLEQ_HEAD_INITIALIZER(nd_queue); >>> + >>> /***********************************************************/ >>> /* network device redirectors */ >>> >>> @@ -1559,6 +1571,19 @@ int net_init_clients(Error **errp) >>> >>> QTAILQ_INIT(&net_clients); >>> >>> + while (!QSIMPLEQ_EMPTY(&nd_queue)) { >>> + NetdevQueueEntry *nd = QSIMPLEQ_FIRST(&nd_queue); >>> + >>> + QSIMPLEQ_REMOVE_HEAD(&nd_queue, entry); >>> + loc_push_restore(&nd->loc); >>> + if (net_client_init1(nd->nd, nd->is_netdev, errp) < 0) { >> >> I think you need to loc_pop() here. >> >>> + return -1; >>> + } >> >> Since the only caller passes &error_fatal, I'd be tempted to ditch the >> @errp argument, and simply do >> >> net_client_init1(nd->nd, nd->is_netdev, &error_fatal); >> >> It's what we do for -blockdev, -device, and -object. > > I've added a patch to remove the @errp from the net_init_clients() arguments. > >> >>> + loc_pop(&nd->loc); >>> + qapi_free_Netdev(nd->nd); >>> + g_free(nd); >>> + } >>> + >>> if (qemu_opts_foreach(qemu_find_opts("netdev"), >>> net_init_netdev, NULL, errp)) { >>> return -1; >>> @@ -1575,8 +1600,37 @@ int net_init_clients(Error **errp) >>> return 0; >>> } >>> >>> +/* >>> + * netdev_is_modern() returns true when the backend needs to bypass >>> + * qemu_opts_parse_noisily() >>> + */ >>> +static bool netdev_is_modern(const char *optarg) >>> +{ >>> + return false; >>> +} >>> + >>> int net_client_parse(QemuOptsList *opts_list, const char *optarg) >>> { >>> + if (netdev_is_modern(optarg)) { >>> + /* >>> + * We need to bypass qemu_opts_parse_noisily() to accept >>> + * new style object like addr.type=inet in SocketAddress >>> + */ >> >> I'm not sure this will makes sense to future readers. >> >> What about "Use modern, more expressive syntax"? > > Done. > >> >>> + Visitor *v; >>> + NetdevQueueEntry *nd; >>> + >>> + v = qobject_input_visitor_new_str(optarg, "type", >>> + &error_fatal); >>> + nd = g_new(NetdevQueueEntry, 1); >>> + visit_type_Netdev(v, NULL, &nd->nd, &error_fatal); >>> + visit_free(v); >>> + loc_save(&nd->loc); >>> + nd->is_netdev = strcmp(opts_list->name, "netdev") == 0; >>> + >>> + QSIMPLEQ_INSERT_TAIL(&nd_queue, nd, entry); >>> + return 0; >>> + } >> >> Matches what we do for -blockdev, except we additionally have >> nd->is_netdev. We need it for calling net_client_init1(). >> >> If netdev_is_modern(optarg), then the only use of parameter @opts_list >> is opts_list->name in the initialization of nd->is_netdev. >> >> There's a bit of code smell, I'm afraid. > > I don't see what is the problem. The function's signature int net_client_parse(QemuOptsList *opts_list, const char *optarg) suggests we're parsing @optarg into @opts_list. We do only if !netdev_is_modern(optarg). In other words, the function's actual behavior doesn't match reasonable expectations based on signature. A function comment would mitigate. If nd->is_netdev wasn't needed, we could code all this just like -blockdev. I think that would be simpler. >> I believe @is_netdev needs to be true for -netdev, -nic, and netdev_add; >> false for -net. >> >> Will we ever use the modern syntax with -net? > > Yes, I think we should support the same syntax with -netdev and -net. > > My first iteration was to pass is_netdev=true to net_client_init1() and Stefano reported a > problem with "-net" with things like that: > > -net dgram,id=socket0,local.type=inet,local.host=localhost,local.port=1234,\ > remote.type=inet,remote.host=localhost,remote.port=1235 > -net nic,model=virtio,macaddr=9a:2b:2c:2d:2e:2f > >> >> Any chance we can deprecate -net? > > Who can decide of that? Thomas, I think you've done some work to replace use cases of -net. Do you know what's left? >>> + >>> if (!qemu_opts_parse_noisily(opts_list, optarg, true)) { >>> return -1; >>> } >> > > Thanks, > Laurent