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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9E7C7ECAAD2 for ; Fri, 2 Sep 2022 01:00:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234653AbiIBBAZ (ORCPT ); Thu, 1 Sep 2022 21:00:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55386 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231752AbiIBBAV (ORCPT ); Thu, 1 Sep 2022 21:00:21 -0400 Received: from gnuweeb.org (gnuweeb.org [51.81.211.47]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 00D4527CE8 for ; Thu, 1 Sep 2022 18:00:17 -0700 (PDT) Received: from localhost.localdomain (unknown [182.2.38.99]) by gnuweeb.org (Postfix) with ESMTPSA id 5BCF78060F; Fri, 2 Sep 2022 01:00:13 +0000 (UTC) X-GW-Data: lPqxHiMPbJw1wb7CM9QUryAGzr0yq5atzVDdxTR0iA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gnuweeb.org; s=default; t=1662080417; bh=VO/rnidcgujqXxV0CuQhSoMG8kd2wmNu8KfPPyEJ1sI=; h=From:To:Cc:Subject:Date:From; b=TYb+MtmCBzmGA63u+TygMGSyZoh8osMcQtX3hD4YhyZzZGSS2svO5TqNrz0BkBPTX R4Qx6k0O2JXuOB8jBGjfTrVGgoVRiDEX3ZUKZMkXNzNvPTktuxDcbhj4V0nJIBoGWp ADkY+kIN6VstQRtb17dY1XeMeJAg802GIXEB0wdQGsT22/mF2XYCQ6MFihB+CVsycp pGLkbM94NgkgpOe3x7zUl+8tenmY6N4tFvpYLR4c+olmPRCmLWobSn/OIA42/Q6I43 atAepwx6taS3/mI+Iv2TFPOFGzZoTSC78/1zZBZNDl1ldwN+2poSeW2O2hzeNAv8c5 hxplegWhsjzmw== From: Ammar Faizi To: Jens Axboe Cc: Ammar Faizi , Dylan Yudaken , Facebook Kernel Team , Pavel Begunkov , Kanna Scarlet , Muhammad Rizki , GNU/Weeb Mailing List , io-uring Mailing List , Linux Kernel Mailing List Subject: [PATCH liburing v1 00/12] Introducing t_bind_ephemeral_port() function Date: Fri, 2 Sep 2022 07:59:34 +0700 Message-Id: <20220902005825.2484023-1-ammar.faizi@intel.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ammar Faizi Hi, After discussing an intermittent bind() issue with Dylan, I decided to introduce a new helper function, t_bind_ephemeral_port(). ## Problem: We have many places where we need to bind() a socket to any unused port number. To achieve that, the current approach does one of the following mechanisms: 1) Randomly brute force the port number until the bind() syscall succeeds. 2) Use a static port at compile time (randomly chosen too). This is not reliable and it results in an intermittent issue (test fails when the selected port is in use). ## Solution: Setting @addr->sin_port to zero on a bind() syscall lets the kernel choose a port number that is not in use. The caller then can know the port number to be bound by invoking a getsockname() syscall after bind() succeeds. Wrap this procedure in a new function called t_bind_ephemeral_port(). The selected port will be returned into @addr->sin_port, the caller can use it later to connect() or whatever they need. ## Patchset summary: There are 12 patches in this series, summary: 1) Patch #1 introduces a new helper function t_bind_ephemeral_port(). 2) Patch #2 to #6 get rid of the port number brute force mechanism. 3) Patch #7 to #12 stop using a static port number. Link: https://lore.kernel.org/r/918facd1-78ba-2de7-693a-5f8c65ea2fcd@gnuweeb.org Cc: Dylan Yudaken Cc: Facebook Kernel Team Cc: Pavel Begunkov Signed-off-by: Ammar Faizi --- Ammar Faizi (12): test/helpers: Add `t_bind_ephemeral_port()` function t/poll-link: Don't brute force the port number t/socket-rw: Don't brute force the port number t/socket-rw-eagain: Don't brute force the port number t/socket-rw-offset: Don't brute force the port number t/files-exit-hang-poll: Don't brute force the port number t/socket: Don't use a static port number t/connect: Don't use a static port number t/shutdown: Don't use a static port number t/recv-msgall: Don't use a static port number t/232c93d07b74: Don't use a static port number t/recv-msgall-stream: Don't use a static port number test/232c93d07b74.c | 10 ++++------ test/accept.c | 5 +---- test/files-exit-hang-poll.c | 23 +++-------------------- test/helpers.c | 18 ++++++++++++++++++ test/helpers.h | 7 +++++++ test/poll-link.c | 20 ++++++-------------- test/recv-msgall-stream.c | 22 ++++++++++------------ test/recv-msgall.c | 10 ++++------ test/shutdown.c | 7 +++---- test/socket-rw-eagain.c | 14 ++------------ test/socket-rw-offset.c | 13 ++----------- test/socket-rw.c | 13 ++----------- test/socket.c | 11 ++++++----- 13 files changed, 68 insertions(+), 105 deletions(-) base-commit: b8c37f02662faa4f2b61840b123201ccc5678fb1 -- Ammar Faizi