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serial: lpc32xx_hs: Use uart_prepare_sysrq_char() to handle sysrq.

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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.

Handle sysrq requests sysrq once the port lock is dropped.
Remove the special case in the console write routine an always use the
complete locking function.

Cc: Vladimir Zapolskiy <vz@mleia.com>
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20240301215246.891055-10-bigeasy@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Sebastian Andrzej Siewior 2024-03-01 22:45:22 +01:00 committed by Greg Kroah-Hartman
parent e544127cc1
commit 6ba5296860
1 changed files with 7 additions and 10 deletions
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17
drivers/tty/serial/lpc32xx_hs.c
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@ -136,20 +136,16 @@ static void lpc32xx_hsuart_console_write(struct console *co, const char *s,
int locked = 1;
touch_nmi_watchdog();
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);
uart_console_write(&up->port, s, count, lpc32xx_hsuart_console_putchar);
wait_for_xmit_empty(&up->port);
if (locked)
uart_port_unlock(&up->port);
local_irq_restore(flags);
uart_port_unlock_irqrestore(&up->port, flags);
}
static int __init lpc32xx_hsuart_console_setup(struct console *co,
@ -266,7 +262,8 @@ static void __serial_lpc32xx_rx(struct uart_port *port)
tty_insert_flip_char(tport, 0, TTY_FRAME);
}
tty_insert_flip_char(tport, (tmp & 0xFF), flag);
if (!uart_prepare_sysrq_char(port, tmp & 0xff))
tty_insert_flip_char(tport, (tmp & 0xFF), flag);
tmp = readl(LPC32XX_HSUART_FIFO(port->membase));
}
@ -331,7 +328,7 @@ static irqreturn_t serial_lpc32xx_interrupt(int irq, void *dev_id)
__serial_lpc32xx_tx(port);
}
uart_port_unlock(port);
uart_unlock_and_check_sysrq(port);
return IRQ_HANDLED;
}