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 X-Spam-Level: X-Spam-Status: No, score=-15.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CB215C433E0 for ; Wed, 10 Mar 2021 18:07:34 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 591BD64FB2 for ; Wed, 10 Mar 2021 18:07:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 591BD64FB2 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:53892 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lK3F7-0006PP-AJ for qemu-devel@archiver.kernel.org; Wed, 10 Mar 2021 13:07:33 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:48958) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lK34Z-0005dx-Uq for qemu-devel@nongnu.org; Wed, 10 Mar 2021 12:56:39 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:47195) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1lK34T-0002Yq-3O for qemu-devel@nongnu.org; Wed, 10 Mar 2021 12:56:39 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1615398990; 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=fNKGKfvfLirnhAjT3LHb9xz//kGe1I7fYty+ALoUSQA=; b=VdtwCxTJINax1B8PZmlU39xEb12fp7LQwGFKw01Od6rCh9QpXRHs3ttvnmFUrf+KfsldUF V9e4HuJ056J9PqYhHQrUr5HsP2f/VOSfdbuw61MFG1ln3t73QrCFbRzQjE2sAF1vPRPYuK 8GOFhHLqok5G4zKLwZvLgFXLgMAqjNo= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-576-SOeCMap4PMSSyoZapW1eLw-1; Wed, 10 Mar 2021 12:56:28 -0500 X-MC-Unique: SOeCMap4PMSSyoZapW1eLw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 426822F7A2 for ; Wed, 10 Mar 2021 17:56:27 +0000 (UTC) Received: from localhost (ovpn-114-91.ams2.redhat.com [10.36.114.91]) by smtp.corp.redhat.com (Postfix) with ESMTP id CA6FF59453; Wed, 10 Mar 2021 17:56:20 +0000 (UTC) Date: Wed, 10 Mar 2021 17:56:19 +0000 From: "Richard W.M. Jones" To: Stefan Hajnoczi Subject: Re: [PATCH] sockets: update SOCKET_ADDRESS_TYPE_FD listen(2) backlog Message-ID: <20210310175619.GS26415@redhat.com> References: <20210310173004.420190-1-stefanha@redhat.com> MIME-Version: 1.0 In-Reply-To: <20210310173004.420190-1-stefanha@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=rjones@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=63.128.21.124; envelope-from=rjones@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.243, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Juan Quintela , Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= , qemu-devel@nongnu.org, Gerd Hoffmann Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Mar 10, 2021 at 05:30:04PM +0000, Stefan Hajnoczi wrote: > socket_get_fd() fails with the error "socket_get_fd: too many > connections" if the given listen backlog value is not 1. > > Not all callers set the backlog to 1. For example, commit > 582d4210eb2f2ab5baac328fe4b479cd86da1647 ("qemu-nbd: Use SOMAXCONN for > socket listen() backlog") uses SOMAXCONN. This will always fail with in > socket_get_fd(). > > This patch calls listen(2) on the fd to update the backlog value. The > socket may already be in the listen state. I have tested that this works > on Linux 5.10 and macOS Catalina. > > As a bonus this allows us to detect when the fd cannot listen. Now we'll > be able to catch unbound or connected fds in socket_listen(). > > Drop the num argument from socket_get_fd() since this function is also > called by socket_connect() where a listen backlog value does not make > sense. > > Fixes: e5b6353cf25c99c3f08bf51e29933352f7140e8f ("socket: Add backlog parameter to socket_listen") > Reported-by: Richard W.M. Jones > Cc: Juan Quintela > Cc: Eric Blake > Signed-off-by: Stefan Hajnoczi I can confirm it fixes the problem found by the libnbd interop test, so: Tested-by: Richard W.M. Jones Rich. > --- > util/qemu-sockets.c | 29 ++++++++++++++++++++++------- > 1 file changed, 22 insertions(+), 7 deletions(-) > > diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c > index 8af0278f15..2463c49773 100644 > --- a/util/qemu-sockets.c > +++ b/util/qemu-sockets.c > @@ -1116,14 +1116,10 @@ fail: > return NULL; > } > > -static int socket_get_fd(const char *fdstr, int num, Error **errp) > +static int socket_get_fd(const char *fdstr, Error **errp) > { > Monitor *cur_mon = monitor_cur(); > int fd; > - if (num != 1) { > - error_setg_errno(errp, EINVAL, "socket_get_fd: too many connections"); > - return -1; > - } > if (cur_mon) { > fd = monitor_get_fd(cur_mon, fdstr, errp); > if (fd < 0) { > @@ -1159,7 +1155,7 @@ int socket_connect(SocketAddress *addr, Error **errp) > break; > > case SOCKET_ADDRESS_TYPE_FD: > - fd = socket_get_fd(addr->u.fd.str, 1, errp); > + fd = socket_get_fd(addr->u.fd.str, errp); > break; > > case SOCKET_ADDRESS_TYPE_VSOCK: > @@ -1187,7 +1183,26 @@ int socket_listen(SocketAddress *addr, int num, Error **errp) > break; > > case SOCKET_ADDRESS_TYPE_FD: > - fd = socket_get_fd(addr->u.fd.str, num, errp); > + fd = socket_get_fd(addr->u.fd.str, errp); > + if (fd < 0) { > + return -1; > + } > + > + /* > + * If the socket is not yet in the listen state, then transition it to > + * the listen state now. > + * > + * If it's already listening then this updates the backlog value as > + * requested. > + * > + * If this socket cannot listen because it's already in another state > + * (e.g. unbound or connected) then we'll catch the error here. > + */ > + if (listen(fd, num) != 0) { > + error_setg_errno(errp, errno, "Failed to listen on fd socket"); > + closesocket(fd); > + return -1; > + } > break; > > case SOCKET_ADDRESS_TYPE_VSOCK: > -- > 2.29.2 > -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-top is 'top' for virtual machines. Tiny program with many powerful monitoring features, net stats, disk stats, logging, etc. http://people.redhat.com/~rjones/virt-top