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=-14.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,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 8C60AC5519F for ; Fri, 20 Nov 2020 08:15:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2DA01223BE for ; Fri, 20 Nov 2020 08:15:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725789AbgKTIPZ (ORCPT ); Fri, 20 Nov 2020 03:15:25 -0500 Received: from mail-lj1-f194.google.com ([209.85.208.194]:38666 "EHLO mail-lj1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725766AbgKTIPZ (ORCPT ); Fri, 20 Nov 2020 03:15:25 -0500 Received: by mail-lj1-f194.google.com with SMTP id r17so9144570ljg.5; Fri, 20 Nov 2020 00:15:23 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=WDs6obGTLR1+wdJ6BVB6dndSCVFd0as/yCTkI8gYmPU=; b=Y/xPta9rvf7YKf4ZukcFJI5daQExV4qAMp40tpHdLOeUXuDb6YQ0Nxn36UQg1WFNWs fkReHJeQ3naoM3VQIjwZ4XVldStY0TJ4BX2LJ8ljlAp9zjrmI/dctR7Sy3LjiuAR0RZf n5u3UgKtTb7Wpcows8hreTNurE4CBobwpn9BgT9wsI6TYy+BvPbn5da0v2yMBt/pbPfs YxdbVnX9O4VvnKXJ5819YZ+C2ZRHA/VH0B0yhsnXZ7dbMBaozuXOx1HM61V3+wbNAlkL +tndx23C+gMd01/d6rBC9swXLkwR/9RZbQ6KsluVbq7OdjbdHmelrz22gCHGCiAZ36dF otIg== X-Gm-Message-State: AOAM533G7gzApWGtyW1HkeXxnghiEHXppCuKQLaVJyKO9P7gEUnk4AIa iUwdqeKeA4LttgM9uv9u0d8= X-Google-Smtp-Source: ABdhPJxmm2fXT+CqTHKLbKnoL9h2nvyj3DpRahFss6PyhtuoOWUmAs/POQ+0B/EFEX06/htv9hKBVw== X-Received: by 2002:a2e:9005:: with SMTP id h5mr6752085ljg.59.1605860122921; Fri, 20 Nov 2020 00:15:22 -0800 (PST) Received: from xi.terra (c-beaee455.07-184-6d6c6d4.bbcust.telenor.se. [85.228.174.190]) by smtp.gmail.com with ESMTPSA id p25sm261261lfc.125.2020.11.20.00.15.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 20 Nov 2020 00:15:21 -0800 (PST) Received: from johan by xi.terra with local (Exim 4.93.0.4) (envelope-from ) id 1kg1Zl-0006KK-9f; Fri, 20 Nov 2020 09:15:26 +0100 Date: Fri, 20 Nov 2020 09:15:25 +0100 From: Johan Hovold To: Tian Tao Cc: gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-arm-kernel@lists.infradead.org, linux-unisoc@lists.infradead.org, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] tty: serial: rad-uart: replace spin_lock_irqsave by spin_lock in hard IRQ Message-ID: References: <1605835613-28359-1-git-send-email-tiantao6@hisilicon.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1605835613-28359-1-git-send-email-tiantao6@hisilicon.com> Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org On Fri, Nov 20, 2020 at 09:26:53AM +0800, Tian Tao wrote: > The code has been in a irq-disabled context since it is hard IRQ. There > is no necessity to do it again. > > Signed-off-by: Tian Tao > --- > drivers/tty/serial/rda-uart.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/drivers/tty/serial/rda-uart.c b/drivers/tty/serial/rda-uart.c > index 85366e0..d6705a0 100644 > --- a/drivers/tty/serial/rda-uart.c > +++ b/drivers/tty/serial/rda-uart.c > @@ -406,10 +406,9 @@ static void rda_uart_receive_chars(struct uart_port *port) > static irqreturn_t rda_interrupt(int irq, void *dev_id) > { > struct uart_port *port = dev_id; > - unsigned long flags; > u32 val, irq_mask; > > - spin_lock_irqsave(&port->lock, flags); > + spin_lock(&port->lock); This will break with forced irq threading (i.e. "threadirqs") since the console code can still end up being called from interrupt context (which can result in a deadlock). > > /* Clear IRQ cause */ > val = rda_uart_read(port, RDA_UART_IRQ_CAUSE); > @@ -426,7 +425,7 @@ static irqreturn_t rda_interrupt(int irq, void *dev_id) > rda_uart_send_chars(port); > } > > - spin_unlock_irqrestore(&port->lock, flags); > + spin_unlock(&port->lock); > > return IRQ_HANDLED; > } Johan