A different KGDB stub

@@ -1198,12 +1198,17 @@
 	spin_unlock_irqrestore(&up->port.lock, flags);
 }
 
+static int released_irq = -1;
+
 static int serial8250_startup(struct uart_port *port)
 {
 	struct uart_8250_port *up = (struct uart_8250_port *)port;
 	unsigned long flags;
 	int retval;
 
+	if (up->port.irq == released_irq)
+		return -EBUSY;
+
 	up->capabilities = uart_config[up->port.type].flags;
 
 	if (up->port.type == PORT_16C950) {

@@ -1869,6 +1874,10 @@
 	for (i = 0; i < UART_NR; i++) {
 		struct uart_8250_port *up = &serial8250_ports[i];
 
+		if (up->port.irq == released_irq) {
+			continue;
+		}
+
 		up->port.line = i;
 		up->port.ops = &serial8250_pops;
 		init_timer(&up->timer);

@@ -2136,6 +2145,36 @@
 void serial8250_resume_port(int line)
 {
 	uart_resume_port(&serial8250_reg, &serial8250_ports[line].port);
+}
+
+/*
+ * Find all the ports using the given irq and shut them down.
+ * Result should be that the irq will be released.
+ * At most one irq can be released this way.
+ * Once an irq is released, any attempts to initialize a port with that irq
+ * will fail with EBUSY.
+ */
+
+int serial8250_release_irq(int irq)
+{
+        struct uart_8250_port *up;
+	int ttyS;
+
+	if (released_irq != -1) {
+		return 1;
+	}
+	released_irq = irq;
+	for (ttyS = 0; ttyS < UART_NR; ttyS++){
+		up =  &serial8250_ports[ttyS];
+		if (up->port.irq == irq && (irq_lists + irq)->head) {
+#ifdef CONFIG_DEBUG_SPINLOCK   /* ugly business... */
+			if(up->port.lock.magic != SPINLOCK_MAGIC)
+				spin_lock_init(&up->port.lock);
+#endif
+			serial8250_shutdown(&up->port);
+		}
+        }
+	return 0;
 }
 
 static int __init serial8250_init(void)

506 lines not on this page · raw message

@@ -1214,6 +1214,10 @@
 	struct uart_state *state = tty->driver_data;
 	struct uart_port *port;
 
+	if (!state)
+		return;
+	port = state->port;
+
 	BUG_ON(!kernel_locked());
 
 	if (!state || !state->port)