serial: msm_serial: disable interrupts in __msm_console_write()

__msm_console_write() assumes that interrupts are disabled, but
with threaded console printers it is possible that the write()
callback of the console is called with interrupts enabled.

Explicitly disable interrupts using local_irq_save() to preserve
the assumed context.
Reported-by: NMarek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: NPetr Mladek <pmladek@suse.com>
Signed-off-by: NJohn Ogness <john.ogness@linutronix.de>
Link: https://lore.kernel.org/r/20220506213324.470461-1-john.ogness@linutronix.deSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/msm_serial.c

@@ -1599,6 +1599,7 @@ static inline struct uart_port *msm_get_port_from_line(unsigned int line)
 static void __msm_console_write(struct uart_port *port, const char *s,
 				unsigned int count, bool is_uartdm)
 {
+	unsigned long flags;
 	int i;
 	int num_newlines = 0;
 	bool replaced = false;
@@ -1616,6 +1617,8 @@ static void __msm_console_write(struct uart_port *port, const char *s,
 			num_newlines++;
 	count += num_newlines;
 
+	local_irq_save(flags);
+
 	if (port->sysrq)
 		locked = 0;
 	else if (oops_in_progress)
@@ -1661,6 +1664,8 @@ static void __msm_console_write(struct uart_port *port, const char *s,
 
 	if (locked)
 		spin_unlock(&port->lock);
+
+	local_irq_restore(flags);
 }
 
 static void msm_console_write(struct console *co, const char *s,