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serial: sifive: 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: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: linux-riscv@lists.infradead.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20240301215246.891055-13-bigeasy@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Sebastian Andrzej Siewior 2024-03-01 22:45:25 +01:00 • committed by Greg Kroah-Hartman
parent bb0b314205
commit 32c694ec3e
1 changed files with 7 additions and 10 deletions
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17
drivers/tty/serial/sifive.c
View file

@ -412,7 +412,8 @@ static void __ssp_receive_chars(struct sifive_serial_port *ssp)
break;
ssp->port.icount.rx++;
uart_insert_char(&ssp->port, 0, 0, ch, TTY_NORMAL);
if (!uart_prepare_sysrq_char(&ssp->port, ch))
uart_insert_char(&ssp->port, 0, 0, ch, TTY_NORMAL);
}
tty_flip_buffer_push(&ssp->port.state->port);
@ -534,7 +535,7 @@ static irqreturn_t sifive_serial_irq(int irq, void *dev_id)
if (ip & SIFIVE_SERIAL_IP_TXWM_MASK)
__ssp_transmit_chars(ssp);
uart_port_unlock(&ssp->port);
uart_unlock_and_check_sysrq(&ssp->port);
return IRQ_HANDLED;
}
@ -791,13 +792,10 @@ static void sifive_serial_console_write(struct console *co, const char *s,
if (!ssp)
return;
local_irq_save(flags);
if (ssp->port.sysrq)
locked = 0;
else if (oops_in_progress)
locked = uart_port_trylock(&ssp->port);
if (oops_in_progress)
locked = uart_port_trylock_irqsave(&ssp->port, &flags);
else
uart_port_lock(&ssp->port);
uart_port_lock_irqsave(&ssp->port, &flags);
ier = __ssp_readl(ssp, SIFIVE_SERIAL_IE_OFFS);
__ssp_writel(0, SIFIVE_SERIAL_IE_OFFS, ssp);
@ -807,8 +805,7 @@ static void sifive_serial_console_write(struct console *co, const char *s,
__ssp_writel(ier, SIFIVE_SERIAL_IE_OFFS, ssp);
if (locked)
uart_port_unlock(&ssp->port);
local_irq_restore(flags);
uart_port_unlock_irqrestore(&ssp->port, flags);
}
static int sifive_serial_console_setup(struct console *co, char *options)