From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754242AbcAVQS7 (ORCPT ); Fri, 22 Jan 2016 11:18:59 -0500 Received: from mail-pf0-f175.google.com ([209.85.192.175]:33556 "EHLO mail-pf0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753124AbcAVQS4 (ORCPT ); Fri, 22 Jan 2016 11:18:56 -0500 Subject: Re: [PATCH 2/4] tty: serial: 8250: add optional spinlock arg to serial8250_rx_chars To: John Ogness , gregkh@linuxfoundation.org References: <877fj1rjs0.fsf@linutronix.de> Cc: vinod.koul@intel.com, dan.j.williams@intel.com, bigeasy@linutronix.de, tony@atomide.com, nsekhar@ti.com, peter.ujfalusi@ti.com, dmaengine@vger.kernel.org, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org From: Peter Hurley Message-ID: <56A2566D.6010408@hurleysoftware.com> Date: Fri, 22 Jan 2016 08:18:53 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: <877fj1rjs0.fsf@linutronix.de> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi John, On 01/22/2016 02:27 AM, John Ogness wrote: > serial8250_rx_chars() must be called from interrupt context and with > the port lock held. The port lock is released temporarily within that > function to call tty_flip_buffer_push(). However, there may be other > drivers that need to synchronize the tty_flip_buffer_push() call within > serial8250_rx_chars() with other contexts. Since the port lock cannot > be used for this synchronization, an optional spinlock argument is added. > If non-NULL, this will be locked during the tty_flip_buffer_push() call. I removed the port lock drop-claim in serial8250_rx_chars in patch "serial: 8250: Remove low_latency workaround" (Greg has this patch in his inbox but not in next because of the merge window). IOW, you can drop this patch. Regards, Peter Hurley