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Message-ID: <20080804151734.0d82fbe9@lxorguk.ukuu.org.uk>
Date: Mon, 4 Aug 2008 15:17:34 +0100
From: Alan Cox <alan@...rguk.ukuu.org.uk>
To: ebiederm@...ssion.com (Eric W. Biederman)
Cc: Yinghai Lu <yhlu.kernel@...il.com>, Ingo Molnar <mingo@...e.hu>,
Thomas Gleixner <tglx@...utronix.de>,
"H. Peter Anvin" <hpa@...or.com>,
Dhaval Giani <dhaval@...ux.vnet.ibm.com>,
Mike Travis <travis@....com>,
Andrew Morton <akpm@...ux-foundation.org>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 21/25] serial: change remove NR_IRQS in 8250.c v2
> Would allow us to use the generic hash table code.
Nice.. that makes the code a bit longer in source form but much clearer
and sharing common design.
> Looks like we can also tweak serial_do_unlink to free irq_info when
> the list goes empty, so we don't have a leak if the driver is ever
> unloaded.
Like this (again not yet tested)
8250: Remove NR_IRQ usage
From: Alan Cox <alan@...hat.com>
---
drivers/serial/68328serial.c | 11 +------
drivers/serial/8250.c | 68 +++++++++++++++++++++++++++++++++---------
2 files changed, 56 insertions(+), 23 deletions(-)
diff --git a/drivers/serial/68328serial.c b/drivers/serial/68328serial.c
index 381b12a..277b78d 100644
--- a/drivers/serial/68328serial.c
+++ b/drivers/serial/68328serial.c
@@ -66,7 +66,6 @@
#endif
static struct m68k_serial m68k_soft[NR_PORTS];
-struct m68k_serial *IRQ_ports[NR_IRQS];
static unsigned int uart_irqs[NR_PORTS] = UART_IRQ_DEFNS;
@@ -375,15 +374,11 @@ clear_and_return:
*/
irqreturn_t rs_interrupt(int irq, void *dev_id)
{
- struct m68k_serial * info;
+ struct m68k_serial * info = dev_id;
m68328_uart *uart;
unsigned short rx;
unsigned short tx;
- info = IRQ_ports[irq];
- if(!info)
- return IRQ_NONE;
-
uart = &uart_addr[info->line];
rx = uart->urx.w;
@@ -1383,8 +1378,6 @@ rs68328_init(void)
info->port, info->irq);
printk(" is a builtin MC68328 UART\n");
- IRQ_ports[info->irq] = info; /* waste of space */
-
#ifdef CONFIG_M68VZ328
if (i > 0 )
PJSEL &= 0xCF; /* PSW enable second port output */
@@ -1393,7 +1386,7 @@ rs68328_init(void)
if (request_irq(uart_irqs[i],
rs_interrupt,
IRQF_DISABLED,
- "M68328_UART", NULL))
+ "M68328_UART", info))
panic("Unable to attach 68328 serial interrupt\n");
}
local_irq_restore(flags);
diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index 342e12f..2245cd4 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -145,11 +145,15 @@ 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.
@@ -1541,9 +1545,32 @@ static void serial_do_unlink(struct irq_info *i, struct uart_8250_port *up)
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);
+ hlist_add_head(&i->node, h);
+ }
+ mutex_unlock(&hash_mutex);
+
spin_lock_irq(&i->lock);
if (i->head) {
@@ -1567,14 +1594,30 @@ 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))
+ if (list_empty(i->head)) {
free_irq(up->port.irq, i);
-
- serial_do_unlink(i, up);
+ serial_do_unlink(i, up);
+ hlist_del(&i->node);
+ kfree(i);
+ } else
+ serial_do_unlink(i, up);
+ mutex_unlock(&hash_mutex);
}
/* Base timer interval for polling */
@@ -2942,7 +2985,7 @@ 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;
@@ -2951,9 +2994,6 @@ 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);
-
ret = uart_register_driver(&serial8250_reg);
if (ret)
goto out;
@@ -2976,11 +3016,11 @@ 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:
uart_unregister_driver(&serial8250_reg);
- out:
+out:
return ret;
}
--
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