Commit 244a758b authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Greg Kroah-Hartman
Browse files

serial: ar933x: 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/20240301215246.891055-3-bigeasy@linutronix.de


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 2432f71c

drivers/tty/serial/ar933x_uart.c

+6 −12
Original line number Diff line number Diff line
@@ -378,7 +378,7 @@ static void ar933x_uart_rx_chars(struct ar933x_uart_port *up) 
		up->port.icount.rx++;

		ch = rdata & AR933X_UART_DATA_TX_RX_MASK;



		if (uart_handle_sysrq_char(&up->port, ch))

		if (uart_prepare_sysrq_char(&up->port, ch))

			continue;



		if ((up->port.ignore_status_mask & AR933X_DUMMY_STATUS_RD) == 0)
@@ -468,7 +468,7 @@ static irqreturn_t ar933x_uart_interrupt(int irq, void *dev_id) 
		ar933x_uart_tx_chars(up);

	}



	uart_port_unlock(&up->port);

	uart_unlock_and_check_sysrq(&up->port);



	return IRQ_HANDLED;

}
@@ -627,14 +627,10 @@ static void ar933x_uart_console_write(struct console *co, const char *s, 
	unsigned int int_en;

	int locked = 1;



	local_irq_save(flags);



	if (up->port.sysrq)

		locked = 0;

	else if (oops_in_progress)

		locked = uart_port_trylock(&up->port);

	if (oops_in_progress)

		locked = uart_port_trylock_irqsave(&up->port, &flags);

	else

		uart_port_lock(&up->port);

		uart_port_lock_irqsave(&up->port, &flags);



	/*

	 * First save the IER then disable the interrupts
@@ -654,9 +650,7 @@ static void ar933x_uart_console_write(struct console *co, const char *s, 
	ar933x_uart_write(up, AR933X_UART_INT_REG, AR933X_UART_INT_ALLINTS);



	if (locked)

		uart_port_unlock(&up->port);



	local_irq_restore(flags);

		uart_port_unlock_irqrestore(&up->port, flags);

}



static int ar933x_uart_console_setup(struct console *co, char *options)