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serial: rda: 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: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-unisoc@lists.infradead.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20240301215246.891055-12-bigeasy@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Sebastian Andrzej Siewior 2024-03-01 22:45:24 +01:00 committed by Greg Kroah-Hartman
parent 2af5214867
commit bb0b314205
1 changed files with 10 additions and 18 deletions
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28
drivers/tty/serial/rda-uart.c
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@ -394,7 +394,8 @@ static void rda_uart_receive_chars(struct uart_port *port)
val &= 0xff;
port->icount.rx++;
tty_insert_flip_char(&port->state->port, val, flag);
if (!uart_prepare_sysrq_char(port, val))
tty_insert_flip_char(&port->state->port, val, flag);
status = rda_uart_read(port, RDA_UART_STATUS);
}
@ -405,10 +406,9 @@ static void rda_uart_receive_chars(struct uart_port *port)
static irqreturn_t rda_interrupt(int irq, void *dev_id)
{
struct uart_port *port = dev_id;
unsigned long flags;
u32 val, irq_mask;
uart_port_lock_irqsave(port, &flags);
uart_port_lock(port);
/* Clear IRQ cause */
val = rda_uart_read(port, RDA_UART_IRQ_CAUSE);
@ -425,7 +425,7 @@ static irqreturn_t rda_interrupt(int irq, void *dev_id)
rda_uart_send_chars(port);
}
uart_port_unlock_irqrestore(port, flags);
uart_unlock_and_check_sysrq(port);
return IRQ_HANDLED;
}
@ -590,18 +590,12 @@ static void rda_uart_port_write(struct uart_port *port, const char *s,
{
u32 old_irq_mask;
unsigned long flags;
int locked;
int locked = 1;
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);
old_irq_mask = rda_uart_read(port, RDA_UART_IRQ_MASK);
rda_uart_write(port, 0, RDA_UART_IRQ_MASK);
@ -615,9 +609,7 @@ static void rda_uart_port_write(struct uart_port *port, const char *s,
rda_uart_write(port, old_irq_mask, RDA_UART_IRQ_MASK);
if (locked)
uart_port_unlock(port);
local_irq_restore(flags);
uart_port_unlock_irqrestore(port, flags);
}
static void rda_uart_console_write(struct console *co, const char *s,