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 1F77BC27C5E for ; Wed, 5 Jun 2024 10:24:48 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sEnoJ-00084M-0e; Wed, 05 Jun 2024 06:24:03 -0400 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 1sEnoD-00082y-LG for qemu-devel@nongnu.org; Wed, 05 Jun 2024 06:24:00 -0400 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 1sEnoB-0001eH-2r for qemu-devel@nongnu.org; Wed, 05 Jun 2024 06:23:57 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1717583033; 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:in-reply-to:in-reply-to: references:references; bh=BKfA898JMMFsYzp/fngAksxsx5GUZp6ZyO/aC0pAqp8=; b=Fhoqzptl43xbD/Ig9OGzljqOzZEQOFVGiza63XCI+NE+PyorB1kETVv6p2akXwQNuWifdm dTqGBFoXM+iu+XpZxEPL0l7wENylSi+0gdAHPMmbkADWtQah09z00u6X9zIXNCfqv9/aR7 mtJYqb5t4RIHUX0PYZeLvT9ZgBRq7aY= Received: from mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-325-tZQjdSBhMWm2JgGrVIabFQ-1; Wed, 05 Jun 2024 06:23:50 -0400 X-MC-Unique: tZQjdSBhMWm2JgGrVIabFQ-1 Received: from mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.15]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 61D6D1944DC6; Wed, 5 Jun 2024 10:23:49 +0000 (UTC) Received: from redhat.com (unknown [10.39.193.183]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 3D71C1956086; Wed, 5 Jun 2024 10:23:46 +0000 (UTC) Date: Wed, 5 Jun 2024 11:23:43 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Jason Wang Cc: peter.maydell@linaro.org, qemu-devel@nongnu.org, Akihiko Odaki Subject: Re: [PULL 07/20] virtio-net: Do not propagate ebpf-rss-fds errors Message-ID: References: <20240604073755.1859-1-jasowang@redhat.com> <20240604073755.1859-8-jasowang@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20240604073755.1859-8-jasowang@redhat.com> User-Agent: Mutt/2.2.12 (2023-09-09) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 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: 12 X-Spam_score: 1.2 X-Spam_bar: + X-Spam_report: (1.2 / 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_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_SBL_CSS=3.335, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-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: , 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 Tue, Jun 04, 2024 at 03:37:42PM +0800, Jason Wang wrote: > From: Akihiko Odaki > > Propagating ebpf-rss-fds errors has several problems. > > First, it makes device realization fail and disables the fallback to the > conventional eBPF loading. AFAICT, this is not a bug - this is desired behaviour. If the user/mgmt app has told QEMU to use FDs it has passed in, then any failure to do this *MUST* be treated as a fatal error. Falling back to other codepaths is ignoring a direct user request. > Second, it leaks memory by making device realization fail without > freeing memory already allocated. > > Third, the convention is to set an error when a function returns false, > but virtio_net_load_ebpf_fds() and virtio_net_load_ebpf() returns false > without setting an error, which is confusing. > > Remove the propagation to fix these problems. It doesn't fix the problems. It ignores the 2nd and 3rd problems by removing the error reporting and ignoring the users' requested config. > > Fixes: 0524ea0510a3 ("ebpf: Added eBPF initialization by fds.") > Signed-off-by: Akihiko Odaki > Signed-off-by: Jason Wang > --- > hw/net/virtio-net.c | 23 ++++++++++------------- > 1 file changed, 10 insertions(+), 13 deletions(-) > > diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c > index ff600b3002..3cee2ef3ac 100644 > --- a/hw/net/virtio-net.c > +++ b/hw/net/virtio-net.c > @@ -1329,24 +1329,22 @@ static void virtio_net_detach_epbf_rss(VirtIONet *n) > virtio_net_attach_ebpf_to_backend(n->nic, -1); > } > > -static bool virtio_net_load_ebpf_fds(VirtIONet *n, Error **errp) > +static bool virtio_net_load_ebpf_fds(VirtIONet *n) > { > int fds[EBPF_RSS_MAX_FDS] = { [0 ... EBPF_RSS_MAX_FDS - 1] = -1}; > int ret = true; > int i = 0; > > - ERRP_GUARD(); > - > if (n->nr_ebpf_rss_fds != EBPF_RSS_MAX_FDS) { > - error_setg(errp, > - "Expected %d file descriptors but got %d", > - EBPF_RSS_MAX_FDS, n->nr_ebpf_rss_fds); > + warn_report("Expected %d file descriptors but got %d", > + EBPF_RSS_MAX_FDS, n->nr_ebpf_rss_fds); > return false; > } > > for (i = 0; i < n->nr_ebpf_rss_fds; i++) { > - fds[i] = monitor_fd_param(monitor_cur(), n->ebpf_rss_fds[i], errp); > - if (*errp) { > + fds[i] = monitor_fd_param(monitor_cur(), n->ebpf_rss_fds[i], > + &error_warn); > + if (fds[i] < 0) { > ret = false; > goto exit; > } > @@ -1355,7 +1353,7 @@ static bool virtio_net_load_ebpf_fds(VirtIONet *n, Error **errp) > ret = ebpf_rss_load_fds(&n->ebpf_rss, fds[0], fds[1], fds[2], fds[3]); > > exit: > - if (!ret || *errp) { > + if (!ret) { > for (i = 0; i < n->nr_ebpf_rss_fds && fds[i] != -1; i++) { > close(fds[i]); > } > @@ -1364,13 +1362,12 @@ exit: > return ret; > } > > -static bool virtio_net_load_ebpf(VirtIONet *n, Error **errp) > +static bool virtio_net_load_ebpf(VirtIONet *n) > { > bool ret = false; > > if (virtio_net_attach_ebpf_to_backend(n->nic, -1)) { > - if (!(n->ebpf_rss_fds > - && virtio_net_load_ebpf_fds(n, errp))) { > + if (!(n->ebpf_rss_fds && virtio_net_load_ebpf_fds(n))) { > ret = ebpf_rss_load(&n->ebpf_rss); > } > } > @@ -3809,7 +3806,7 @@ static void virtio_net_device_realize(DeviceState *dev, Error **errp) > net_rx_pkt_init(&n->rx_pkt); > > if (virtio_has_feature(n->host_features, VIRTIO_NET_F_RSS)) { > - virtio_net_load_ebpf(n, errp); > + virtio_net_load_ebpf(n); > } > } > > -- > 2.42.0 > > 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 :|