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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 30A7FC169C4 for ; Thu, 31 Jan 2019 05:59:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0B69420881 for ; Thu, 31 Jan 2019 05:59:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726013AbfAaF7w (ORCPT ); Thu, 31 Jan 2019 00:59:52 -0500 Received: from shards.monkeyblade.net ([23.128.96.9]:55250 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725875AbfAaF7v (ORCPT ); Thu, 31 Jan 2019 00:59:51 -0500 Received: from localhost (unknown [IPv6:2601:601:9f80:35cd::bf5]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id 0E39C14F48D7F; Wed, 30 Jan 2019 21:59:51 -0800 (PST) Date: Wed, 30 Jan 2019 21:59:50 -0800 (PST) Message-Id: <20190130.215950.1443919738399463157.davem@davemloft.net> To: vakul.garg@nxp.com Cc: netdev@vger.kernel.org, borisp@mellanox.com, aviadye@mellanox.com, davejwatson@fb.com, doronrk@fb.com Subject: Re: [PATCH net-next] strparser: Return if socket does not have required number of bytes From: David Miller In-Reply-To: <20190130072933.23281-1-vakul.garg@nxp.com> References: <20190130072933.23281-1-vakul.garg@nxp.com> X-Mailer: Mew version 6.8 on Emacs 26.1 Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Wed, 30 Jan 2019 21:59:51 -0800 (PST) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Vakul Garg Date: Wed, 30 Jan 2019 07:31:44 +0000 > Function strp_data_ready() should peek the associated socket to check > whether it has the required number of bytes available before queueing > work or initiating socket read via strp_read_sock(). This saves cpu > cycles because strp_read_sock() is called only when required amount of > data is available. > > Signed-off-by: Vakul Garg You can't do this, I think. It's racy and the user socket owned check is absolutely necessary before you do the need bytes check.