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: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20240301215246.891055-8-bigeasy@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/pxa.c b/drivers/tty/serial/pxa.c
index 46e70e1..e395ff2 100644 (file)
--- a/drivers/tty/serial/pxa.c
+++ b/drivers/tty/serial/pxa.c
@@ -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