mirrors/linux-stable
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git synced 2024-09-28 21:33:52 +00:00
Code Issues Releases Wiki Activity

serial: pch: Use uart_prepare_sysrq_char().

Browse source 
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.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20240301215246.891055-19-bigeasy@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Sebastian Andrzej Siewior 2024-03-01 22:45:31 +01:00 committed by Greg Kroah-Hartman
parent 06d28ca0c6
commit d47dd323bf
1 changed files with 9 additions and 15 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

24
drivers/tty/serial/pch_uart.c
View file

@ -564,7 +564,7 @@ static int pch_uart_hal_read(struct eg20t_port *priv, unsigned char *buf,
if (uart_handle_break(port))
continue;
}
if (uart_handle_sysrq_char(port, rbr))
if (uart_prepare_sysrq_char(port, rbr))
continue;
buf[i++] = rbr;
@ -1070,7 +1070,7 @@ static irqreturn_t pch_uart_interrupt(int irq, void *dev_id)
handled |= (unsigned int)ret;
}
uart_port_unlock(&priv->port);
uart_unlock_and_check_sysrq(&priv->port);
return IRQ_RETVAL(handled);
}
@ -1550,22 +1550,17 @@ pch_console_write(struct console *co, const char *s, unsigned int count)
{
struct eg20t_port *priv;
unsigned long flags;
int port_locked = 1;
int locked = 1;
u8 ier;
priv = pch_uart_ports[co->index];
touch_nmi_watchdog();
local_irq_save(flags);
if (priv->port.sysrq) {
/* serial8250_handle_port() already took the port lock */
port_locked = 0;
} else if (oops_in_progress) {
port_locked = uart_port_trylock(&priv->port);
} else {
uart_port_lock(&priv->port);
}
if (oops_in_progress)
locked = uart_port_trylock_irqsave(&priv->port, &flags);
else
uart_port_lock_irqsave(&priv->port, &flags);
/*
* First save the IER then disable the interrupts
@ -1583,9 +1578,8 @@ pch_console_write(struct console *co, const char *s, unsigned int count)
wait_for_xmitr(priv, UART_LSR_BOTH_EMPTY);
iowrite8(ier, priv->membase + UART_IER);
if (port_locked)
uart_port_unlock(&priv->port);
local_irq_restore(flags);
if (locked)
uart_port_unlock_irqrestore(&priv->port, flags);
}
static int __init pch_console_setup(struct console *co, char *options)