Commit 51f7ed07 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Greg Kroah-Hartman
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serial: pxa: 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/20240301215246.891055-8-bigeasy@linutronix.de


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 63bd93ac

drivers/tty/serial/pxa.c

+6 −11
Original line number Diff line number Diff line
@@ -151,7 +151,7 @@ static inline void receive_chars(struct uart_pxa_port *up, int *status) 
				flag = TTY_FRAME;

		}



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

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

			goto ignore_char;



		uart_insert_char(&up->port, *status, UART_LSR_OE, ch, flag);
@@ -232,7 +232,7 @@ static inline irqreturn_t serial_pxa_irq(int irq, void *dev_id) 
	check_modem_status(up);

	if (lsr & UART_LSR_THRE)

		transmit_chars(up);

	uart_port_unlock(&up->port);

	uart_unlock_and_check_sysrq(&up->port);

	return IRQ_HANDLED;

}
@@ -604,13 +604,10 @@ serial_pxa_console_write(struct console *co, const char *s, unsigned int count) 
	int locked = 1;



	clk_enable(up->clk);

	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
@@ -628,10 +625,8 @@ serial_pxa_console_write(struct console *co, const char *s, unsigned int count) 
	serial_out(up, UART_IER, ier);



	if (locked)

		uart_port_unlock(&up->port);

	local_irq_restore(flags);

		uart_port_unlock_irqrestore(&up->port, flags);

	clk_disable(up->clk);



}



#ifdef CONFIG_CONSOLE_POLL