Commit bb0b3142 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Greg Kroah-Hartman
Browse files

serial: rda: Use uart_prepare_sysrq_char() to handle sysrq. 



The port lock is a spinlock_t which is becomes a sleeping lock on PREEMPT_RT.
The driver splits the locking function into two parts: local_irq_save() and
uart_port_lock() and this breaks PREEMPT_RT.

Handle sysrq requests sysrq once the port lock is dropped.
Remove the special case in the console write routine an always use the
complete locking function.

Cc: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-unisoc@lists.infradead.org
Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20240301215246.891055-12-bigeasy@linutronix.de


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 2af52148

drivers/tty/serial/rda-uart.c

+10 −18
Original line number Diff line number Diff line
@@ -394,6 +394,7 @@ static void rda_uart_receive_chars(struct uart_port *port) 
		val &= 0xff;



		port->icount.rx++;

		if (!uart_prepare_sysrq_char(port, val))

			tty_insert_flip_char(&port->state->port, val, flag);



		status = rda_uart_read(port, RDA_UART_STATUS);
@@ -405,10 +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;



	uart_port_lock_irqsave(port, &flags);

	uart_port_lock(port);



	/* Clear IRQ cause */

	val = rda_uart_read(port, RDA_UART_IRQ_CAUSE);
@@ -425,7 +425,7 @@ static irqreturn_t rda_interrupt(int irq, void *dev_id) 
		rda_uart_send_chars(port);

	}



	uart_port_unlock_irqrestore(port, flags);

	uart_unlock_and_check_sysrq(port);



	return IRQ_HANDLED;

}
@@ -590,18 +590,12 @@ static void rda_uart_port_write(struct uart_port *port, const char *s, 
{

	u32 old_irq_mask;

	unsigned long flags;

	int locked;



	local_irq_save(flags);

	int locked = 1;



	if (port->sysrq) {

		locked = 0;

	} else if (oops_in_progress) {

		locked = uart_port_trylock(port);

	} else {

		uart_port_lock(port);

		locked = 1;

	}

	if (oops_in_progress)

		locked = uart_port_trylock_irqsave(port, &flags);

	else

		uart_port_lock_irqsave(port, &flags);



	old_irq_mask = rda_uart_read(port, RDA_UART_IRQ_MASK);

	rda_uart_write(port, 0, RDA_UART_IRQ_MASK);
@@ -615,9 +609,7 @@ static void rda_uart_port_write(struct uart_port *port, const char *s, 
	rda_uart_write(port, old_irq_mask, RDA_UART_IRQ_MASK);



	if (locked)

		uart_port_unlock(port);



	local_irq_restore(flags);

		uart_port_unlock_irqrestore(port, flags);

}



static void rda_uart_console_write(struct console *co, const char *s,