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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 9DEFDC433B4 for ; Mon, 12 Apr 2021 04:34:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 64D03611C9 for ; Mon, 12 Apr 2021 04:34:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229642AbhDLEeq (ORCPT ); Mon, 12 Apr 2021 00:34:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36968 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229448AbhDLEep (ORCPT ); Mon, 12 Apr 2021 00:34:45 -0400 Received: from mail-pg1-x52a.google.com (mail-pg1-x52a.google.com [IPv6:2607:f8b0:4864:20::52a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C8127C061574; Sun, 11 Apr 2021 21:34:27 -0700 (PDT) Received: by mail-pg1-x52a.google.com with SMTP id k8so8412825pgf.4; Sun, 11 Apr 2021 21:34:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=K4FzIBSzTsQ26tiQe4PAL44Y27//vbAmCEDS6LTwbEM=; b=DgBvVHftT42xTT0vc6hT9qUxbNBbvXuy/qYZYanVEzW5vP2DYbBKl5L2SB/sWFGveQ KdGhyuY+fVTMgL/mi6ZA1z6XEFH5rpiOSPJCwmCPJvCCaazANz7hfPN9j4jjYTLtStMP lK37lB6hjgeIyFvcS8vuqDpj0gCMks6fdZcS/E6kGqxdUOsrkRIcVxIJj+UzJVyQwr34 dHGI9bohVJwepdoQIKA7m3vLiCuzSqtihSDBau9BueMbZC/p+U8yUUI/wWVh2NrJx1Mv 1t8eYmIcpt1ZgJRa/ncPIqNPBWqYrwvrzZVpO5HwZT4hyOueX3EYiaajuVdyYSkb5sIj ZMdw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=K4FzIBSzTsQ26tiQe4PAL44Y27//vbAmCEDS6LTwbEM=; b=EOE+8By/AdTlqb1b7k/7LelSIFEEih2KNunS34YUB343ITvAFyoWuGAyHQgbtxsP6h NO066qppqqJ3K1xDGRr+2It+P9UlA2z0jQSIcWO6woKhwxjwY9MFo3jvAk5iiswqfeme IPLifehIhxtius1IKr5v57LIVPr3CIJ8IKLFz0nJEuWkT+gWWeRDxGfUy1KgEZEQ+XfA JW5T0U4t0gTRbLGudLfbKpJmSTk854FceZMtTYg6Oi/KxTjPtHJJNZllXiIJTQNUUsXn NJ3wXI3gxXvog4F0gY/Z9J0bBTHfbT77dQUxPJZ9GyBPftI4SngkgenHiwuE/6jdx5NZ MsMA== X-Gm-Message-State: AOAM530BQq8VCOESFPJx1kCwNti+tcvo9TKhgUAwcvSE2aDvIwF99Tbp A1z9mjDEGVQ9gUUgo0er0kqBx0y2Rvs6BqFm X-Google-Smtp-Source: ABdhPJyC9TZOi5ElW12Bo8Vkj6uRwcHCKeSZXzF3Rubx1D6zPTP1D29tM+y7o5O0TK3VlvylLTYESQ== X-Received: by 2002:a63:dd14:: with SMTP id t20mr24986189pgg.258.1618202067450; Sun, 11 Apr 2021 21:34:27 -0700 (PDT) Received: from fmin-OptiPlex-7060.nreal.work ([137.59.103.165]) by smtp.gmail.com with ESMTPSA id o13sm9777411pgv.40.2021.04.11.21.34.24 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Sun, 11 Apr 2021 21:34:26 -0700 (PDT) From: dillon.minfei@gmail.com To: gregkh@linuxfoundation.org, jirislaby@kernel.org, mcoquelin.stm32@gmail.com, alexandre.torgue@foss.st.com Cc: linux-serial@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, dillon min Subject: [PATCH] serial: stm32: optimize spin lock usage Date: Mon, 12 Apr 2021 12:34:21 +0800 Message-Id: <1618202061-8243-1-git-send-email-dillon.minfei@gmail.com> X-Mailer: git-send-email 2.7.4 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: dillon min To avoid potential deadlock in spin_lock usage, change to use spin_lock_irqsave(), spin_unlock_irqrestore() in process(thread_fn) context. spin_lock(), spin_unlock() under handler context. remove unused local_irq_save/restore call. Signed-off-by: dillon min --- Was verified on stm32f469-disco board. need more test on stm32mp platform. drivers/tty/serial/stm32-usart.c | 27 +++++++++++++++++---------- 1 file changed, 17 insertions(+), 10 deletions(-) diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index b3675cf25a69..c4c859b34367 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -214,7 +214,7 @@ static void stm32_usart_receive_chars(struct uart_port *port, bool threaded) struct tty_port *tport = &port->state->port; struct stm32_port *stm32_port = to_stm32_port(port); const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs; - unsigned long c; + unsigned long c, flags; u32 sr; char flag; @@ -276,9 +276,17 @@ static void stm32_usart_receive_chars(struct uart_port *port, bool threaded) uart_insert_char(port, sr, USART_SR_ORE, c, flag); } - spin_unlock(&port->lock); + if (threaded) + spin_unlock_irqrestore(&port->lock, flags); + else + spin_unlock(&port->lock); + tty_flip_buffer_push(tport); - spin_lock(&port->lock); + + if (threaded) + spin_lock_irqsave(&port->lock, flags); + else + spin_lock(&port->lock); } static void stm32_usart_tx_dma_complete(void *arg) @@ -489,13 +497,14 @@ static irqreturn_t stm32_usart_threaded_interrupt(int irq, void *ptr) { struct uart_port *port = ptr; struct stm32_port *stm32_port = to_stm32_port(port); + unsigned long flags; - spin_lock(&port->lock); + spin_lock_irqsave(&port->lock, flags); if (stm32_port->rx_ch) stm32_usart_receive_chars(port, true); - spin_unlock(&port->lock); + spin_unlock_irqrestore(&port->lock, flags); return IRQ_HANDLED; } @@ -1354,13 +1363,12 @@ static void stm32_usart_console_write(struct console *co, const char *s, u32 old_cr1, new_cr1; int locked = 1; - local_irq_save(flags); if (port->sysrq) locked = 0; else if (oops_in_progress) - locked = spin_trylock(&port->lock); + locked = spin_trylock_irqsave(&port->lock, flags); else - spin_lock(&port->lock); + spin_lock_irqsave(&port->lock, flags); /* Save and disable interrupts, enable the transmitter */ old_cr1 = readl_relaxed(port->membase + ofs->cr1); @@ -1374,8 +1382,7 @@ static void stm32_usart_console_write(struct console *co, const char *s, writel_relaxed(old_cr1, port->membase + ofs->cr1); if (locked) - spin_unlock(&port->lock); - local_irq_restore(flags); + spin_unlock_irqrestore(&port->lock, flags); } static int stm32_usart_console_setup(struct console *co, char *options) -- 2.7.4