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serial: meson: Use uart_prepare_sysrq_char().

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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.

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: Kevin Hilman <khilman@baylibre.com>
Cc: Jerome Brunet <jbrunet@baylibre.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-amlogic@lists.infradead.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20240301215246.891055-5-bigeasy@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Sebastian Andrzej Siewior 2024-03-01 22:45:17 +01:00 committed by Greg Kroah-Hartman
parent 8c1cbc5a2b
commit fb793b952a
1 changed files with 8 additions and 14 deletions
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22
drivers/tty/serial/meson_uart.c
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@ -220,7 +220,7 @@ static void meson_receive_chars(struct uart_port *port)
continue;
}
if (uart_handle_sysrq_char(port, ch))
if (uart_prepare_sysrq_char(port, ch))
continue;
if ((status & port->ignore_status_mask) == 0)
@ -248,7 +248,7 @@ static irqreturn_t meson_uart_interrupt(int irq, void *dev_id)
meson_uart_start_tx(port);
}
uart_port_unlock(port);
uart_unlock_and_check_sysrq(port);
return IRQ_HANDLED;
}
@ -556,18 +556,13 @@ static void meson_serial_port_write(struct uart_port *port, const char *s,
u_int count)
{
unsigned long flags;
int locked;
int locked = 1;
u32 val, tmp;
local_irq_save(flags);
if (port->sysrq) {
locked = 0;
} else if (oops_in_progress) {
locked = uart_port_trylock(port);
} else {
uart_port_lock(port);
locked = 1;
}
if (oops_in_progress)
locked = uart_port_trylock_irqsave(port, &flags);
else
uart_port_lock_irqsave(port, &flags);
val = readl(port->membase + AML_UART_CONTROL);
tmp = val & ~(AML_UART_TX_INT_EN | AML_UART_RX_INT_EN);
@ -577,8 +572,7 @@ static void meson_serial_port_write(struct uart_port *port, const char *s,
writel(val, port->membase + AML_UART_CONTROL);
if (locked)
uart_port_unlock(port);
local_irq_restore(flags);
uart_port_unlock_irqrestore(port, flags);
}
static void meson_serial_console_write(struct console *co, const char *s,