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 <dillon.minfei@gmail.com> Subject: [PATCH] serial: stm32: optimize spin lock usage Date: Mon, 12 Apr 2021 12:34:21 +0800 [thread overview] Message-ID: <1618202061-8243-1-git-send-email-dillon.minfei@gmail.com> (raw) From: dillon min <dillon.minfei@gmail.com> 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 <dillon.minfei@gmail.com> --- 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
WARNING: multiple messages have this Message-ID (diff)
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 <dillon.minfei@gmail.com> Subject: [PATCH] serial: stm32: optimize spin lock usage Date: Mon, 12 Apr 2021 12:34:21 +0800 [thread overview] Message-ID: <1618202061-8243-1-git-send-email-dillon.minfei@gmail.com> (raw) From: dillon min <dillon.minfei@gmail.com> 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 <dillon.minfei@gmail.com> --- 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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next reply other threads:[~2021-04-12 4:34 UTC|newest] Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-04-12 4:34 dillon.minfei [this message] 2021-04-12 4:34 ` [PATCH] serial: stm32: optimize spin lock usage dillon.minfei 2021-04-12 5:52 ` Greg KH 2021-04-12 5:52 ` Greg KH 2021-04-12 6:50 ` dillon min 2021-04-12 6:50 ` dillon min 2021-04-12 8:25 ` Greg KH 2021-04-12 8:25 ` Greg KH 2021-04-12 8:54 ` dillon min 2021-04-12 8:54 ` dillon min 2021-04-12 13:19 ` [Linux-stm32] " Erwan LE RAY 2021-04-12 13:19 ` Erwan LE RAY 2021-04-12 13:41 ` dillon min 2021-04-12 13:41 ` dillon min 2021-04-12 7:23 ` kernel test robot 2021-04-12 7:23 ` kernel test robot 2021-04-12 7:23 ` kernel test robot 2021-04-12 7:29 ` dillon min 2021-04-12 7:29 ` dillon min 2021-04-12 7:29 ` dillon min 2021-04-12 10:50 kernel test robot
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