[PATCH] serial: change remove NR_IRQS in 8250.c

[Yinghai Lu <yhlu.kernel@gmail.com>]

replace
	[PATCH] serial: change irq_lists to use dyn_array
use small array with index to handle irq locking for serial port
hope 32 slot is enough

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>

---
 drivers/serial/8250.c |   73 +++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 67 insertions(+), 6 deletions(-)

Index: linux-2.6/drivers/serial/8250.c
===================================================================
--- linux-2.6.orig/drivers/serial/8250.c
+++ linux-2.6/drivers/serial/8250.c
@@ -149,7 +149,55 @@ struct irq_info {
 	struct list_head	*head;
 };
 
-static struct irq_info irq_lists[NR_IRQS];
+struct irq_info_pair {
+	struct irq_info irq_info;
+	int irq_no;
+};
+
+#define NR_IRQ_INFO_PAIR	32
+
+static struct irq_info_pair irq_pair_lists[NR_IRQ_INFO_PAIR] = {
+	[0 ... NR_IRQ_INFO_PAIR-1] = {
+		.irq_no = -1,
+	}
+};
+
+static struct irq_info *get_irq_info(int irq, int with_free)
+{
+	int i, first_free = -1;
+
+	for (i = 0; i < NR_IRQ_INFO_PAIR; i++) {
+		if (irq_pair_lists[i].irq_no == irq)
+			return &irq_pair_lists[i].irq_info;
+		if (irq_pair_lists[i].irq_no == -1 && first_free == -1)
+			first_free = i;
+	}
+	if (!with_free)
+		return NULL;
+
+	if (first_free != -1) {
+		irq_pair_lists[first_free].irq_no = irq;
+		return &irq_pair_lists[first_free].irq_info;
+	}
+
+	WARN_ON("NR_IRQ_INFO_PAIR too small");
+
+	return NULL;
+}
+
+static void check_free_irq_info(int irq_no)
+{
+
+	int i;
+
+	for (i = 0; i < NR_IRQ_INFO_PAIR; i++) {
+		if (irq_pair_lists[i].irq_no != irq_no)
+			continue;
+
+		irq_pair_lists[i].irq_no = -1;
+		break;
+	}
+}
 
 /*
  * Here we define the default xmit fifo size used for each type of UART.
@@ -1554,9 +1602,12 @@ static void serial_do_unlink(struct irq_
 
 static int serial_link_irq_chain(struct uart_8250_port *up)
 {
-	struct irq_info *i = irq_lists + up->port.irq;
+	struct irq_info *i = get_irq_info(up->port.irq, 1);
 	int ret, irq_flags = up->port.flags & UPF_SHARE_IRQ ? IRQF_SHARED : 0;
 
+	if (!i)
+		return -1;
+
 	spin_lock_irq(&i->lock);
 
 	if (i->head) {
@@ -1580,14 +1631,24 @@ static int serial_link_irq_chain(struct
 
 static void serial_unlink_irq_chain(struct uart_8250_port *up)
 {
-	struct irq_info *i = irq_lists + up->port.irq;
+	int irq_no = up->port.irq;
+	struct irq_info *i = get_irq_info(irq_no, 0);
+	int empty = 0;
+
+	if (!i)
+		return;
 
 	BUG_ON(i->head == NULL);
 
-	if (list_empty(i->head))
+	if (list_empty(i->head)) {
 		free_irq(up->port.irq, i);
+		empty = 1;
+	}
 
 	serial_do_unlink(i, up);
+
+	if (empty)
+		check_free_irq_info(irq_no);
 }
 
 /* Base timer interval for polling */
@@ -2964,8 +3025,8 @@ 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);
+	for (i = 0; i < NR_IRQ_INFO_PAIR; i++)
+		spin_lock_init(&irq_pair_lists[i].irq_info.lock);
 
 	ret = uart_register_driver(&serial8250_reg);
 	if (ret)