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Date: Thu, 31 Jul 2008 01:26:12 -0700
From: Yinghai Lu <yhlu.kernel@...il.com>
To: Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
"H. Peter Anvin" <hpa@...or.com>,
"Eric W. Biederman" <ebiederm@...ssion.com>,
Dhaval Giani <dhaval@...ux.vnet.ibm.com>,
Mike Travis <travis@....com>,
Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH] serial: change remove NR_IRQS in 8250.c
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@...il.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)
--
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