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Subject[PATCH 21/33] serial: change remove NR_IRQS in 8250.c v2
Date
use small array with index to handle irq locking for serial port
hope 32 slot is enough

v2: according to Eric, move irq_no into irq_info, and not clean irq_no

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
---
drivers/serial/8250.c | 45 +++++++++++++++++++++++++++++++++++++++++----
1 files changed, 41 insertions(+), 4 deletions(-)
diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index 3920324..595b956 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -147,9 +147,39 @@ struct uart_8250_port {
struct irq_info {
spinlock_t lock;
struct list_head *head;
+ int irq_no;
};

-static struct irq_info irq_lists[NR_IRQS];
+#define NR_IRQ_INFO 32
+
+static struct irq_info irq_lists[NR_IRQ_INFO] = {
+ [0 ... NR_IRQ_INFO-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; i++) {
+ if (irq_lists[i].irq_no == irq)
+ return &irq_lists[i];
+ if (irq_lists[i].irq_no == -1 && first_free == -1)
+ first_free = i;
+ }
+ if (!with_free)
+ return NULL;
+
+ if (first_free != -1) {
+ irq_lists[first_free].irq_no = irq;
+ return &irq_lists[first_free];
+ }
+
+ WARN_ON("NR_IRQ_INFO too small");
+
+ return NULL;
+}

/*
* Here we define the default xmit fifo size used for each type of UART.
@@ -1554,9 +1584,12 @@ 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 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) {
@@ -1580,7 +1613,11 @@ 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;
+ int irq_no = up->port.irq;
+ struct irq_info *i = get_irq_info(irq_no, 0);
+
+ if (!i)
+ return;

BUG_ON(i->head == NULL);

@@ -2964,7 +3001,7 @@ 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++)
+ for (i = 0; i < NR_IRQ_INFO; i++)
spin_lock_init(&irq_lists[i].lock);

ret = uart_register_driver(&serial8250_reg);
--
1.5.4.5


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