and fix the ns16550 driver to cope with suprise remove

diff --git a/master/cope-with-dead-serial b/master/cope-with-dead-serial
index 7eab790aa474a59cffb276ab467d0615ce7218d9..e8c88f7ab4a9d9638cc598b4320c8a32f2cbafb3 100644 (file)
--- a/master/cope-with-dead-serial
+++ b/master/cope-with-dead-serial
@@ -1,3 +1,33 @@
+diff --git a/xen/drivers/char/ns16550.c b/xen/drivers/char/ns16550.c
+index 5fdfd91..5caf362 100644
+--- a/xen/drivers/char/ns16550.c
++++ b/xen/drivers/char/ns16550.c
+@@ -127,8 +127,9 @@ static void ns16550_interrupt(
+ {
+     struct serial_port *port = dev_id;
+     struct ns16550 *uart = port->uart;
++    int bail = 0;
+ 
+-    while ( !(ns_read_reg(uart, IIR) & IIR_NOINT) )
++    while ( !(ns_read_reg(uart, IIR) & IIR_NOINT) && (bail++ < 0x20))
+     {
+         char lsr = ns_read_reg(uart, LSR);
+         if ( lsr & LSR_THRE )
+@@ -143,11 +144,12 @@ static void ns16550_poll(void *data)
+     struct serial_port *port = data;
+     struct ns16550 *uart = port->uart;
+     struct cpu_user_regs *regs = guest_cpu_user_regs();
++    int bail = 0;
+ 
+-    while ( ns_read_reg(uart, LSR) & LSR_DR )
++    while ( (ns_read_reg(uart, LSR) & LSR_DR ) && (bail++ < 0x20))
+         serial_rx_interrupt(port, regs);
+ 
+-    if ( ns_read_reg(uart, LSR) & LSR_THRE )
++    if ( (ns_read_reg(uart, LSR) & LSR_THRE ) && (bail++ < 0x20))
+         serial_tx_interrupt(port, regs);
+ 
+     set_timer(&uart->timer, NOW() + MILLISECS(uart->timeout_ms));
 diff --git a/xen/drivers/char/serial.c b/xen/drivers/char/serial.c
 index 3d261ca..88512ae 100644
 --- a/xen/drivers/char/serial.c