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serial: owl: 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: Andreas Färber <afaerber@suse.de>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-actions@lists.infradead.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20240301215246.891055-11-bigeasy@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Sebastian Andrzej Siewior 2024-03-01 22:45:23 +01:00 committed by Greg Kroah-Hartman
parent 6ba5296860
commit 2af5214867
1 changed files with 12 additions and 18 deletions
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30
drivers/tty/serial/owl-uart.c
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@ -199,6 +199,7 @@ static void owl_uart_receive_chars(struct uart_port *port)
stat = owl_uart_read(port, OWL_UART_STAT);
while (!(stat & OWL_UART_STAT_RFEM)) {
char flag = TTY_NORMAL;
bool sysrq;
if (stat & OWL_UART_STAT_RXER)
port->icount.overrun++;
@ -217,7 +218,9 @@ static void owl_uart_receive_chars(struct uart_port *port)
val = owl_uart_read(port, OWL_UART_RXDAT);
val &= 0xff;
if ((stat & port->ignore_status_mask) == 0)
sysrq = uart_prepare_sysrq_char(port, val);
if (!sysrq && (stat & port->ignore_status_mask) == 0)
tty_insert_flip_char(&port->state->port, val, flag);
stat = owl_uart_read(port, OWL_UART_STAT);
@ -229,10 +232,9 @@ static void owl_uart_receive_chars(struct uart_port *port)
static irqreturn_t owl_uart_irq(int irq, void *dev_id)
{
struct uart_port *port = dev_id;
unsigned long flags;
u32 stat;
uart_port_lock_irqsave(port, &flags);
uart_port_lock(port);
stat = owl_uart_read(port, OWL_UART_STAT);
@ -246,7 +248,7 @@ static irqreturn_t owl_uart_irq(int irq, void *dev_id)
stat |= OWL_UART_STAT_RIP | OWL_UART_STAT_TIP;
owl_uart_write(port, stat, OWL_UART_STAT);
uart_port_unlock_irqrestore(port, flags);
uart_unlock_and_check_sysrq(port);
return IRQ_HANDLED;
}
@ -508,18 +510,12 @@ static void owl_uart_port_write(struct uart_port *port, const char *s,
{
u32 old_ctl, val;
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_ctl = owl_uart_read(port, OWL_UART_CTL);
val = old_ctl | OWL_UART_CTL_TRFS_TX;
@ -541,9 +537,7 @@ static void owl_uart_port_write(struct uart_port *port, const char *s,
owl_uart_write(port, old_ctl, OWL_UART_CTL);
if (locked)
uart_port_unlock(port);
local_irq_restore(flags);
uart_port_unlock_irqrestore(port, flags);
}
static void owl_uart_console_write(struct console *co, const char *s,