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=-3.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,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 E4638C433E0 for ; Thu, 2 Jul 2020 05:12:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B693E207CD for ; Thu, 2 Jul 2020 05:12:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="dDsTSnXP" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726122AbgGBFMT (ORCPT ); Thu, 2 Jul 2020 01:12:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45966 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725872AbgGBFMS (ORCPT ); Thu, 2 Jul 2020 01:12:18 -0400 Received: from mail-pf1-x441.google.com (mail-pf1-x441.google.com [IPv6:2607:f8b0:4864:20::441]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A93AEC08C5C1 for ; Wed, 1 Jul 2020 22:12:18 -0700 (PDT) Received: by mail-pf1-x441.google.com with SMTP id m9so1747834pfh.0 for ; Wed, 01 Jul 2020 22:12:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:date:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=LunmkpyZTHjgvSZKdw92/F6exJ7yKjpP4k5iFcGt28Q=; b=dDsTSnXPiEBlNGdlw746l9Jhs+Cj1VfEbbIqgnDKkr3kny+xfAsdKYTA4A+5kxbPTD p3ARECQsBHl/fijxFyKq03lfamgW7IUVTczcVRtH/OvH5xQA6etzZd1ty3SID0f9UldF PoxzH+ZPbtHNRbrY6mHEcd90FgcRX/4ZRyZVHuoO1rChK+ubmF+N+U+u5kIkwKKYzwFt cxHsi5K2DRhhylaE//qPr6gOOQPy1xQ1KLFJOlnZeClscdafeihrfIZAZaJBLlLS8tbA aAcaH08GXbcTXA6RXyDqYSTkbbkL0IBerQLFkKsHmnttoAc/SLHoUGYuFPXVywEvCJst 5y0w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:date:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=LunmkpyZTHjgvSZKdw92/F6exJ7yKjpP4k5iFcGt28Q=; b=mpW3iB25eaLjYtPj+KBHn3pvSN7YXmIkrr47ynjCgxHvta+NLTDt4FQveS7jg4IGv6 tMbzAQ4t733IXirp1XjLWvgEdGcayoUDl62/V2HMsKRnhWt/pnVpaYtroZjr0tP8+UMG PPuMEfW9NUxM5THfm2yVQgLpHc3pPjNJxch+zvrWbs+3MIdUDa+14VP60wWbAPNZlXxE az+eQgqeMf8YMj8R0BApxuuCkf+LtcZiMR5JeeP/D1yXJ1KUdab+Gz/AzBSwNpU0k3hs koaEpCzFF4sCXbQqE0y1EfCa2ORZwymyT6/1SVUTdEkIqpUWJfsNN++RHc6VHLWWgova 4daw== X-Gm-Message-State: AOAM5334/S9TzgFMMY+ICokVo+Sl2WAmtNpY3T8gbxO6KKbprduE9gwQ UT4nTN9xYbo1lHPK1q3USoo= X-Google-Smtp-Source: ABdhPJxMZdJq5xnjLSHUgz2b3jwE/YnUT1m7sRTojshV5EHUamLHjmCJU/utJPHm/i8ACTRpWrWYrw== X-Received: by 2002:a63:8ec7:: with SMTP id k190mr17165652pge.261.1593666737980; Wed, 01 Jul 2020 22:12:17 -0700 (PDT) Received: from localhost ([2409:10:2e40:5100:6e29:95ff:fe2d:8f34]) by smtp.gmail.com with ESMTPSA id z3sm7258006pfz.38.2020.07.01.22.12.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 01 Jul 2020 22:12:17 -0700 (PDT) From: Sergey Senozhatsky X-Google-Original-From: Sergey Senozhatsky Date: Thu, 2 Jul 2020 14:12:13 +0900 To: Tony Lindgren Cc: Sergey Senozhatsky , Petr Mladek , Andy Shevchenko , Raul Rangel , Sergey Senozhatsky , linux-kernel , Greg Kroah-Hartman , Andy Shevchenko , kurt@linutronix.de, "S, Shirish" , Peter Zijlstra , John Ogness , Steven Rostedt Subject: Re: UART/TTY console deadlock Message-ID: <20200702051213.GB3450@jagdpanzerIV.localdomain> References: <20200630035816.GA21591@jagdpanzerIV.localdomain> <20200630102141.GA11587@alley> <20200630105512.GA530@jagdpanzerIV.localdomain> <20200630122239.GD6173@alley> <20200630130534.GB145027@jagdpanzerIV.localdomain> <20200630180255.GD37466@atomide.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200630180255.GD37466@atomide.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (20/06/30 11:02), Tony Lindgren wrote: > This conditional disable for irq_shared does not look nice to me > from the other device point of view :) > > Would it be possible to just set up te dummy interrupt handler > for the startup, then change it back afterwards? See for example > omap8250_no_handle_irq(). I think we can do it. serial8250_do_startup() and irq handler take port->lock, so they should be synchronized. Something like this then? --- diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index f77bf820b7a3..61ad6f5f0f88 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -2140,6 +2140,11 @@ static void serial8250_put_poll_char(struct uart_port *port, #endif /* CONFIG_CONSOLE_POLL */ +static int serial8250_dummy_handle_irq(struct uart_port *port) +{ + return 0; +} + int serial8250_do_startup(struct uart_port *port) { struct uart_8250_port *up = up_to_u8250p(port); @@ -2271,6 +2276,9 @@ int serial8250_do_startup(struct uart_port *port) if (port->irq && !(up->port.flags & UPF_NO_THRE_TEST)) { unsigned char iir1; + int (*handler)(struct uart_port *); + + handler = port->handle_irq; /* * Test for UARTs that do not reassert THRE when the * transmitter is idle and the interrupt has already @@ -2280,8 +2288,7 @@ int serial8250_do_startup(struct uart_port *port) * allow register changes to become visible. */ spin_lock_irqsave(&port->lock, flags); - if (up->port.irqflags & IRQF_SHARED) - disable_irq_nosync(port->irq); + port->handle_irq = serial8250_dummy_handle_irq; wait_for_xmitr(up, UART_LSR_THRE); serial_port_out_sync(port, UART_IER, UART_IER_THRI); @@ -2293,8 +2300,7 @@ int serial8250_do_startup(struct uart_port *port) iir = serial_port_in(port, UART_IIR); serial_port_out(port, UART_IER, 0); - if (port->irqflags & IRQF_SHARED) - enable_irq(port->irq); + port->handle_irq = handler; spin_unlock_irqrestore(&port->lock, flags); /*