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Message-ID: <86802c440808031220p3f9b9f7ay733cc886bbab99c4@mail.gmail.com>
Date: Sun, 3 Aug 2008 12:20:41 -0700
From: "Yinghai Lu" <yhlu.kernel@...il.com>
To: "Eric W. Biederman" <ebiederm@...ssion.com>,
"Alan Cox" <alan@...rguk.ukuu.org.uk>
Cc: "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 00/25] dyn_array and nr_irqs support v3
On Sun, Aug 3, 2008 at 10:54 AM, Yinghai Lu <yhlu.kernel@...il.com> wrote:
>>> * Each architecture has to answer this themself.
>>>
>>>
>>> and later use get_irq_desc(i) instead irq_desc + i;
>>
>> That is the general idea.
>
> could use pre_allocate array + list to replace irq_desc array.
>
how about this one?
diff --git a/include/linux/irq.h b/include/linux/irq.h
index bd69d90..9d87f6a 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -154,6 +154,8 @@ struct irq_chip {
* @name: flow handler name for /proc/interrupts output
*/
struct irq_desc {
+ unsigned int irq;
+ struct irq_desc *next;
irq_flow_handler_t handle_irq;
struct irq_chip *chip;
struct msi_desc *msi_desc;
@@ -181,7 +183,7 @@ struct irq_desc {
const char *name;
} ____cacheline_internodealigned_in_smp;
-extern struct irq_desc irq_desc[NR_IRQS];
+extern struct irq_desc *get_irq_desc(unsigned int irq);
/*
* Migration helpers for obsolete names, they will go away:
diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index e9d022c..347edb8 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -48,7 +48,90 @@ handle_bad_irq(unsigned int irq, struct irq_desc *desc)
* Controller mappings for all interrupt sources:
*/
int nr_irqs = NR_IRQS;
-struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned_in_smp = {
+
+#ifdef CONFIG_HAVE_DYN_ARRAY
+static struct irq_desc irq_desc_init __initdata = {
+ .irq = -1U;
+ .status = IRQ_DISABLED,
+ .chip = &no_irq_chip,
+ .handle_irq = handle_bad_irq,
+ .depth = 1,
+ .lock = __SPIN_LOCK_UNLOCKED(irq_desc->lock),
+#ifdef CONFIG_SMP
+ .affinity = CPU_MASK_ALL
+#endif
+};
+
+static int nr_irq_desc = NR_VECTORS;
+
+static int __init parse_nr_irq_desc(char *arg)
+{
+ if (arg)
+ nr_irq_desc = simple_strtoul(arg, NULL, 0);
+ return 0;
+}
+
+early_param("nr_irq_desc", parse_nr_irq_desc);
+
+static void __init init_work(void *data)
+{
+ struct dyn_array *da = data;
+ int i;
+ struct irq_desc *desc;
+
+ desc = *da->name;
+
+ for (i = 0; i < *da->nr; i++)
+ memcpy(&desc[i], &irq_desc_init, sizeof(struct irq_desc));
+
+ for (i = 1; i < *da->nr; i++)
+ desc[i-1].next = &desc[i];
+}
+
+static struct irq_desc *irq_desc;
+DEFINE_DYN_ARRAY(irq_desc, sizeof(struct irq_desc), nr_irq_desc,
PAGE_SIZE, init_work);
+
+struct irq_desc *get_irq_desc(unsigned int irq)
+{
+ struct irq_desc *desc, *desc_pri;
+
+ BUG_ON(irq == -1U);
+
+ desc = &irq_desc[0];
+ while (desc) {
+ if (desc->irq == irq)
+ return desc;
+
+ if (desc->irq == -1U) {
+ desc->irq = irq;
+ return desc;
+ }
+ desc_pri = desc;
+ desc = desc->next;
+ }
+
+ /*
+ * we run out of pre-allocate ones
+ * and __alloc_bootmem or kzalloc could be used
+ */
+
+ if (after_bootmem)
+ desc = (struct irq_desc *) get_zeroed_page(GFP_ATOMIC);
+ else
+ desc = alloc_bootmem_pages(PAGE_SIZE);
+
+ if (!desc || ((unsigned long)desc & ~PAGE_MASK))
+ panic("please boot with nr_irq_desc= %d\n", nr_irq_desc * 2);
+
+ desc_pri->next = desc;
+ desc->irq = irq;
+
+ return desc;
+}
+
+#else
+
+static struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned_in_smp = {
[0 ... NR_IRQS-1] = {
.status = IRQ_DISABLED,
.chip = &no_irq_chip,
@@ -61,6 +144,16 @@ struct irq_desc irq_desc[NR_IRQS]
__cacheline_aligned_in_smp = {
}
};
+struct irq_desc *get_irq_desc(unsigned int irq)
+{
+ if (irq < nr_irqs)
+ return &irq_desc[irq];
+
+ return NULL;
+}
+
+#endif
+
/*
* What should we do if we get a hw irq event on an illegal vector?
* Each architecture has to answer this themself.
do we need to lock to avoid racing in get_irq_desc?
YH
--
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