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=-5.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 AC37EC433B4 for ; Thu, 22 Apr 2021 10:09:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7AB2F61417 for ; Thu, 22 Apr 2021 10:09:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235769AbhDVKKZ (ORCPT ); Thu, 22 Apr 2021 06:10:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:40426 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230285AbhDVKKY (ORCPT ); Thu, 22 Apr 2021 06:10:24 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 03DA961360; Thu, 22 Apr 2021 10:09:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1619086189; bh=awCVv/+J9oV/6dLNqikCNFKD0Fj3UTsswF2nac3PjCk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=QKoHtwKxXISmjsMNeYfv1GPhCNUAorA5WtPNyLfzvN+lsIcctMyk5llR1QtJs8AfK Dwd0Spbn5aUfeIV69rgHf+Jv4F121GLV/0MCnix6/BRfnoN/FZ+KGOwAZwANmXxI/C SI+HskUsAI384wFeCV2j/MClGodsh/pxF6qtEs54= Date: Thu, 22 Apr 2021 12:09:47 +0200 From: Greg Kroah-Hartman To: Johan Hovold Cc: Jiri Slaby , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 00/26] tty: drop low-latency workarounds Message-ID: References: <20210421095509.3024-1-johan@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210421095509.3024-1-johan@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 21, 2021 at 11:54:43AM +0200, Johan Hovold wrote: > The infamous low_latency behaviour of tty_flip_buffer_push(), which > meant that data could be pushed to the line discipline immediately > instead of being deferred to a work queue, was finally removed in 2014. > > Since then there's no need for drivers to keep hacks to temporarily drop > the port lock during receive processing but this pattern has been > reproduced in later added drivers nonetheless. > > Note that several of these workarounds were added by a series posted in > 2013, which ended up being merged despite having completely nonsensical > commit messages. As it turned out, it was just the RT patch set which > effectively enabled the low_latency flag for serial drivers that did not > handle it. > > There's of course nothing wrong releasing the port lock before calling > tty_flip_buffer_push(), and some drivers still do after this series, but > let's get rid of the completely unnecessary unlock-and-reacquire > pattern. Many thanks for cleaning up this old crud, all now applied. greg k-h