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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Fri, 1 Mar 2024 22:45:21 +0100
Subject: [PATCH 08/18] serial: sunplus: Use uart_prepare_sysrq_char().
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.8/older/patches-6.8.2-rt11.tar.xz
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.
Cc: Hammer Hsieh <hammerh0314@gmail.com>
Link: https://lore.kernel.org/r/20240301215246.891055-9-bigeasy@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
drivers/tty/serial/sunplus-uart.c | 18 ++++++------------
1 file changed, 6 insertions(+), 12 deletions(-)
--- a/drivers/tty/serial/sunplus-uart.c
+++ b/drivers/tty/serial/sunplus-uart.c
@@ -260,7 +260,7 @@ static void receive_chars(struct uart_po
if (port->ignore_status_mask & SUP_DUMMY_READ)
goto ignore_char;
- if (uart_handle_sysrq_char(port, ch))
+ if (uart_prepare_sysrq_char(port, ch))
goto ignore_char;
uart_insert_char(port, lsr, SUP_UART_LSR_OE, ch, flag);
@@ -287,7 +287,7 @@ static irqreturn_t sunplus_uart_irq(int
if (isc & SUP_UART_ISC_TX)
transmit_chars(port);
- uart_port_unlock(port);
+ uart_unlock_and_check_sysrq(port);
return IRQ_HANDLED;
}
@@ -512,22 +512,16 @@ static void sunplus_console_write(struct
unsigned long flags;
int locked = 1;
- local_irq_save(flags);
-
- if (sunplus_console_ports[co->index]->port.sysrq)
- locked = 0;
- else if (oops_in_progress)
- locked = uart_port_trylock(&sunplus_console_ports[co->index]->port);
+ if (oops_in_progress)
+ locked = uart_port_trylock_irqsave(&sunplus_console_ports[co->index]->port, &flags);
else
- uart_port_lock(&sunplus_console_ports[co->index]->port);
+ uart_port_lock_irqsave(&sunplus_console_ports[co->index]->port, &flags);
uart_console_write(&sunplus_console_ports[co->index]->port, s, count,
sunplus_uart_console_putchar);
if (locked)
- uart_port_unlock(&sunplus_console_ports[co->index]->port);
-
- local_irq_restore(flags);
+ uart_port_unlock_irqrestore(&sunplus_console_ports[co->index]->port, flags);
}
static int __init sunplus_console_setup(struct console *co, char *options)
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