Commit 8c1cbc5a authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Greg Kroah-Hartman
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serial: bcm63xx: Use uart_prepare_sysrq_char(). 



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.

Delay handling sysrq until port lock is dropped.
Remove the special case in the console write routine an always use the
complete locking function.

Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20240301215246.891055-4-bigeasy@linutronix.de


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 244a758b

drivers/tty/serial/bcm63xx_uart.c

+8 −16
Original line number Diff line number Diff line
@@ -285,10 +285,9 @@ static void bcm_uart_do_rx(struct uart_port *port) 
				flag = TTY_PARITY;

		}



		if (uart_handle_sysrq_char(port, c))

		if (uart_prepare_sysrq_char(port, c))

			continue;





		if ((cstat & port->ignore_status_mask) == 0)

			tty_insert_flip_char(tty_port, c, flag);
@@ -353,7 +352,7 @@ static irqreturn_t bcm_uart_interrupt(int irq, void *dev_id) 
					       estat & UART_EXTINP_DCD_MASK);

	}



	uart_port_unlock(port);

	uart_unlock_and_check_sysrq(port);

	return IRQ_HANDLED;

}
@@ -703,20 +702,14 @@ static void bcm_console_write(struct console *co, const char *s, 
{

	struct uart_port *port;

	unsigned long flags;

	int locked;

	int locked = 1;



	port = &ports[co->index];



	local_irq_save(flags);

	if (port->sysrq) {

		/* bcm_uart_interrupt() already took the lock */

		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);



	/* call helper to deal with \r\n */

	uart_console_write(port, s, count, bcm_console_putchar);
@@ -725,8 +718,7 @@ static void bcm_console_write(struct console *co, const char *s, 
	wait_for_xmitr(port);



	if (locked)

		uart_port_unlock(port);

	local_irq_restore(flags);

		uart_port_unlock_irqrestore(port, flags);

}



/*