1 files changed, 55 insertions, 12 deletions

diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index d3ca7d32abe0..c66bb44c4747 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -156,11 +156,15 @@ struct uart_8250_port {
 };
 
 struct irq_info {
-	spinlock_t		lock;
+	struct			hlist_node node;
+	int			irq;
+	spinlock_t		lock;	/* Protects list not the hash */
 	struct list_head	*head;
 };
 
-static struct irq_info irq_lists[NR_IRQS];
+#define NR_IRQ_HASH		32	/* Can be adjusted later */
+static struct hlist_head irq_lists[NR_IRQ_HASH];
+static DEFINE_MUTEX(hash_mutex);	/* Used to walk the hash */
 
 /*
  * Here we define the default xmit fifo size used for each type of UART.
@@ -1545,15 +1549,43 @@ static void serial_do_unlink(struct irq_info *i, struct uart_8250_port *up)
 		BUG_ON(i->head != &up->list);
 		i->head = NULL;
 	}
-
 	spin_unlock_irq(&i->lock);
+	/* List empty so throw away the hash node */
+	if (i->head == NULL) {
+		hlist_del(&i->node);
+		kfree(i);
+	}
 }
 
 static int serial_link_irq_chain(struct uart_8250_port *up)
 {
-	struct irq_info *i = irq_lists + up->port.irq;
+	struct hlist_head *h;
+	struct hlist_node *n;
+	struct irq_info *i;
 	int ret, irq_flags = up->port.flags & UPF_SHARE_IRQ ? IRQF_SHARED : 0;
 
+	mutex_lock(&hash_mutex);
+
+	h = &irq_lists[up->port.irq % NR_IRQ_HASH];
+
+	hlist_for_each(n, h) {
+		i = hlist_entry(n, struct irq_info, node);
+		if (i->irq == up->port.irq)
+			break;
+	}
+
+	if (n == NULL) {
+		i = kzalloc(sizeof(struct irq_info), GFP_KERNEL);
+		if (i == NULL) {
+			mutex_unlock(&hash_mutex);
+			return -ENOMEM;
+		}
+		spin_lock_init(&i->lock);
+		i->irq = up->port.irq;
+		hlist_add_head(&i->node, h);
+	}
+	mutex_unlock(&hash_mutex);
+
 	spin_lock_irq(&i->lock);
 
 	if (i->head) {
@@ -1577,14 +1609,28 @@ static int serial_link_irq_chain(struct uart_8250_port *up)
 
 static void serial_unlink_irq_chain(struct uart_8250_port *up)
 {
-	struct irq_info *i = irq_lists + up->port.irq;
+	struct irq_info *i;
+	struct hlist_node *n;
+	struct hlist_head *h;
 
+	mutex_lock(&hash_mutex);
+
+	h = &irq_lists[up->port.irq % NR_IRQ_HASH];
+
+	hlist_for_each(n, h) {
+		i = hlist_entry(n, struct irq_info, node);
+		if (i->irq == up->port.irq)
+			break;
+	}
+
+	BUG_ON(n == NULL);
 	BUG_ON(i->head == NULL);
 
 	if (list_empty(i->head))
 		free_irq(up->port.irq, i);
 
 	serial_do_unlink(i, up);
+	mutex_unlock(&hash_mutex);
 }
 
 /* Base timer interval for polling */
@@ -2960,7 +3006,7 @@ EXPORT_SYMBOL(serial8250_unregister_port);
 
 static int __init serial8250_init(void)
 {
-	int ret, i;
+	int ret;
 
 	if (nr_uarts > UART_NR)
 		nr_uarts = UART_NR;
@@ -2969,9 +3015,6 @@ static int __init serial8250_init(void)
 		"%d ports, IRQ sharing %sabled\n", nr_uarts,
 		share_irqs ? "en" : "dis");
 
-	for (i = 0; i < NR_IRQS; i++)
-		spin_lock_init(&irq_lists[i].lock);
-
 #ifdef CONFIG_SPARC
 	ret = sunserial_register_minors(&serial8250_reg, UART_NR);
 #else
@@ -2999,15 +3042,15 @@ static int __init serial8250_init(void)
 		goto out;
 
 	platform_device_del(serial8250_isa_devs);
- put_dev:
+put_dev:
 	platform_device_put(serial8250_isa_devs);
- unreg_uart_drv:
+unreg_uart_drv:
 #ifdef CONFIG_SPARC
 	sunserial_unregister_minors(&serial8250_reg, UART_NR);
 #else
 	uart_unregister_driver(&serial8250_reg);
 #endif
- out:
+out:
 	return ret;
 }