drivers-serial-cleanup-locking-for-rt.patch

From: Ingo Molnar <mingo@elte.hu>
Date: Fri, 3 Jul 2009 08:30:01 -0500
Subject: serial: 8250: Clean up the locking for -rt

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

---
 drivers/tty/serial/8250/8250.c |   15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

Index: linux-stable/drivers/tty/serial/8250/8250.c
===================================================================
--- linux-stable.orig/drivers/tty/serial/8250/8250.c
+++ linux-stable/drivers/tty/serial/8250/8250.c
@@ -2773,14 +2773,10 @@ serial8250_console_write(struct console 
 
 	touch_nmi_watchdog();
 
-	local_irq_save(flags);
-	if (port->sysrq) {
-		/* serial8250_handle_irq() already took the lock */
-		locked = 0;
-	} else if (oops_in_progress) {
-		locked = spin_trylock(&port->lock);
-	} else
-		spin_lock(&port->lock);
+	if (port->sysrq || oops_in_progress)
+		locked = spin_trylock_irqsave(&port->lock, flags);
+	else
+		spin_lock_irqsave(&port->lock, flags);
 
 	/*
 	 *	First save the IER then disable the interrupts
@@ -2812,8 +2808,7 @@ serial8250_console_write(struct console 
 		serial8250_modem_status(up);
 
 	if (locked)
-		spin_unlock(&port->lock);
-	local_irq_restore(flags);
+		spin_unlock_irqrestore(&port->lock, flags);
 }
 
 static int __init serial8250_console_setup(struct console *co, char *options)