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serial: stm32: defer sysrq processing

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Use the uart_unlock_and_check_sysrq() helper to defer sysrq processing
until receive processing is done and the port lock has been released.

This allows cleaning up the console_write() implementation by not having
to work around the recursive sysrq case (by dropping locking completely)
and also makes the console code work with PREEMPT_RT by no longer
relying on local_irq_save().

Reviewed-by: Valentin Caron<valentin.caron@foss.st.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210416140557.25177-4-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Johan Hovold 2021-04-16 16:05:57 +02:00 committed by Greg Kroah-Hartman
parent e359b4411c
commit cea37afd28
1 changed files with 6 additions and 10 deletions
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16
drivers/tty/serial/stm32-usart.c
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@ -270,12 +270,12 @@ static void stm32_usart_receive_chars(struct uart_port *port, bool threaded)
}
}
if (uart_handle_sysrq_char(port, c))
if (uart_prepare_sysrq_char(port, c))
continue;
uart_insert_char(port, sr, USART_SR_ORE, c, flag);
}
spin_unlock(&port->lock);
uart_unlock_and_check_sysrq(port);
tty_flip_buffer_push(tport);
}
@ -1430,13 +1430,10 @@ 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);
if (oops_in_progress)
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);
@ -1450,8 +1447,7 @@ 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)