[SERIAL] 8250: add locking to console write function
x86 SMP breaks as a result of the previous change, we have no real
option other than to add locking to the 8250 console write function.
If an oops is in progress, try to acquire the lock. If we fail to
do so, continue anyway.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index e001ea0..bbf78aa 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -2235,10 +2235,17 @@
serial8250_console_write(struct console *co, const char *s, unsigned int count)
{
struct uart_8250_port *up = &serial8250_ports[co->index];
+ unsigned long flags;
unsigned int ier;
+ int locked = 1;
touch_nmi_watchdog();
+ if (oops_in_progress) {
+ locked = spin_trylock_irqsave(&up->port.lock, flags);
+ } else
+ spin_lock_irqsave(&up->port.lock, flags);
+
/*
* First save the IER then disable the interrupts
*/
@@ -2257,6 +2264,9 @@
*/
wait_for_xmitr(up, BOTH_EMPTY);
serial_out(up, UART_IER, ier);
+
+ if (locked)
+ spin_unlock_irqrestore(&up->port.lock, flags);
}
static int serial8250_console_setup(struct console *co, char *options)
