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bh=K4FzIBSzTsQ26tiQe4PAL44Y27//vbAmCEDS6LTwbEM=; b=hyAjf5Gu/W+FkPbKvHGuqau3X7nWT0NG8kHWMT43b5t5iwU+cVaZmPly7jzndpvwWk rfiL6rKzSnF1EXoTN4E/3datV1lhqm9ZH5ZlaWyF0Vte0RUkp2xNO761a9jxfZ4Vmtpq TQBXAj5nioE2bjZDHLsJAS35/5HcxYMohwN3+mhHdiKkq1jLTvaAsbu+pTqcgRrtnmhL egRTaxHjTkwpRS63Zq3cuYhOcKeBfW/SY0CBpV9QUu3ZP9/V0EJQW4k8G239f812nZ7c HxRIkjLIxMGgQjcj+V+qAgNDE5GstHUVU+skzGNajcwxZHu2I8yS8/S6AfZtZcTcDalR cztw== X-Gm-Message-State: AOAM531nW03erHHUxEDeB3RakJUNHpPnz/L2PqIGks2X+LFvHKexsXuw CSZZZwPwGG9CUXXg0OwVfZY= 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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210411_213431_404905_3F0727A7 X-CRM114-Status: GOOD ( 13.41 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.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 Reported-by: kernel test robot --- 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)