[PATCH] ns16550: ensure polling timer is disarmed

[dmkhn@xxxxxxxxx]

From: Denis Mukhin <dmukhin@xxxxxxxx> 

As it stands, polling timer is kept in the list of timers even after the
interrupts have been enabled / polling disabled on ns16550-compatible UART.

Ensure polling timer is removed from the timer list once UART interrupts are
enabled.

Signed-off-by: Denis Mukhin <dmukhin@xxxxxxxx>
---
 xen/drivers/char/ns16550.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/xen/drivers/char/ns16550.c b/xen/drivers/char/ns16550.c
index df7fff7f81df..299773d80065 100644
--- a/xen/drivers/char/ns16550.c
+++ b/xen/drivers/char/ns16550.c
@@ -191,6 +191,10 @@ static void cf_check ns16550_interrupt(int irq, void 
*dev_id)
     struct serial_port *port = dev_id;
     struct ns16550 *uart = port->uart;
 
+    /* Ensure polling timer is disarmed and removed from the timer list. */
+    if ( !uart->intr_works )
+        kill_timer(&uart->timer);
+
     uart->intr_works = 1;
 
     while ( !(ns_read_reg(uart, UART_IIR) & UART_IIR_NOINT) )
-- 
2.34.1