From patchwork Sun Jun 5 07:42:45 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michael Tokarev X-Patchwork-Id: 9155129 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id BDAC860221 for ; Sun, 5 Jun 2016 07:50:10 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A364227C8F for ; Sun, 5 Jun 2016 07:50:10 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 8454328210; Sun, 5 Jun 2016 07:50:10 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id E9CDB27C8F for ; Sun, 5 Jun 2016 07:50:09 +0000 (UTC) Received: from localhost ([::1]:35798 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b9Soy-000897-J1 for patchwork-qemu-devel@patchwork.kernel.org; Sun, 05 Jun 2016 03:50:08 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58932) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b9Sim-0002yH-5n for qemu-devel@nongnu.org; Sun, 05 Jun 2016 03:43:45 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1b9Sig-0004Oy-Ev for qemu-devel@nongnu.org; Sun, 05 Jun 2016 03:43:44 -0400 Received: from isrv.corpit.ru ([86.62.121.231]:56642) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b9Sig-0004OU-7g; Sun, 05 Jun 2016 03:43:38 -0400 Received: from tsrv.tls.msk.ru (tsrv.tls.msk.ru [192.168.177.2]) by isrv.corpit.ru (Postfix) with ESMTP id 49BE240912; Sun, 5 Jun 2016 10:43:33 +0300 (MSK) Received: from tls.msk.ru (mjt.vpn.tls.msk.ru [192.168.177.99]) by tsrv.tls.msk.ru (Postfix) with SMTP id BAAE1928; Sun, 5 Jun 2016 10:43:32 +0300 (MSK) Received: (nullmailer pid 1105 invoked by uid 1000); Sun, 05 Jun 2016 07:43:32 -0000 From: Michael Tokarev To: qemu-devel@nongnu.org Date: Sun, 5 Jun 2016 10:42:45 +0300 Message-Id: <0b49921d791e56830e9f93bea4de20208244fff2.1465112552.git.mjt@msgid.tls.msk.ru> X-Mailer: git-send-email 2.1.4 In-Reply-To: References: X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 86.62.121.231 Subject: [Qemu-devel] [PULL 08/52] gdbstub: set listen backlog to 1 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-trivial@nongnu.org, Michael Tokarev , Peter Wu Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP From: Peter Wu Avoid possible connection drops on Linux (when tcp_syncookies is disabled) or fallbacks to SYN cookies with the following kernel warning: TCP: request_sock_TCP: Possible SYN flooding on port 1234. Sending cookies. Check SNMP counters. Since Linux 4.4 (ef547f2ac16b "tcp: remove max_qlen_log"), a backlog of zero is really treated as the "queue length for completely established sockets waiting to be accepted" (listen(2)). This is apparently a valid interpretation of an "implementation-defined minimum value" for a backlog value of 0 (listen(3p)). Previous kernels would use 8 as minimum value, but that is no longer the case. Signed-off-by: Peter Wu Signed-off-by: Michael Tokarev --- gdbstub.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/gdbstub.c b/gdbstub.c index b9e3710..ffcad0e 100644 --- a/gdbstub.c +++ b/gdbstub.c @@ -1629,7 +1629,7 @@ static int gdbserver_open(int port) close(fd); return -1; } - ret = listen(fd, 0); + ret = listen(fd, 1); if (ret < 0) { perror("listen"); close(fd);