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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Fri, 1 Mar 2024 22:45:20 +0100
Subject: [PATCH 07/18] serial: pxa: 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.
Link: https://lore.kernel.org/r/20240301215246.891055-8-bigeasy@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
drivers/tty/serial/pxa.c | 17 ++++++-----------
1 file changed, 6 insertions(+), 11 deletions(-)
--- a/drivers/tty/serial/pxa.c
+++ b/drivers/tty/serial/pxa.c
@@ -151,7 +151,7 @@ static inline void receive_chars(struct
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
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
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
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
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