Linux-2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

kernel/irq/handle.c

@@ -0,0 +1,193 @@
+/*
+ * linux/kernel/irq/handle.c
+ *
+ * Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar
+ *
+ * This file contains the core interrupt handling code.
+ */
+
+#include <linux/irq.h>
+#include <linux/module.h>
+#include <linux/random.h>
+#include <linux/interrupt.h>
+#include <linux/kernel_stat.h>
+
+#include "internals.h"
+
+/*
+ * Linux has a controller-independent interrupt architecture.
+ * Every controller has a 'controller-template', that is used
+ * by the main code to do the right thing. Each driver-visible
+ * interrupt source is transparently wired to the apropriate
+ * controller. Thus drivers need not be aware of the
+ * interrupt-controller.
+ *
+ * The code is designed to be easily extended with new/different
+ * interrupt controllers, without having to do assembly magic or
+ * having to touch the generic code.
+ *
+ * Controller mappings for all interrupt sources:
+ */
+irq_desc_t irq_desc[NR_IRQS] __cacheline_aligned = {
+	[0 ... NR_IRQS-1] = {
+		.handler = &no_irq_type,
+		.lock = SPIN_LOCK_UNLOCKED
+	}
+};
+
+/*
+ * Generic 'no controller' code
+ */
+static void end_none(unsigned int irq) { }
+static void enable_none(unsigned int irq) { }
+static void disable_none(unsigned int irq) { }
+static void shutdown_none(unsigned int irq) { }
+static unsigned int startup_none(unsigned int irq) { return 0; }
+
+static void ack_none(unsigned int irq)
+{
+	/*
+	 * 'what should we do if we get a hw irq event on an illegal vector'.
+	 * each architecture has to answer this themself.
+	 */
+	ack_bad_irq(irq);
+}
+
+struct hw_interrupt_type no_irq_type = {
+	.typename = 	"none",
+	.startup = 	startup_none,
+	.shutdown = 	shutdown_none,
+	.enable = 	enable_none,
+	.disable = 	disable_none,
+	.ack = 		ack_none,
+	.end = 		end_none,
+	.set_affinity = NULL
+};
+
+/*
+ * Special, empty irq handler:
+ */
+irqreturn_t no_action(int cpl, void *dev_id, struct pt_regs *regs)
+{
+	return IRQ_NONE;
+}
+
+/*
+ * Have got an event to handle:
+ */
+fastcall int handle_IRQ_event(unsigned int irq, struct pt_regs *regs,
+				struct irqaction *action)
+{
+	int ret, retval = 0, status = 0;
+
+	if (!(action->flags & SA_INTERRUPT))
+		local_irq_enable();
+
+	do {
+		ret = action->handler(irq, action->dev_id, regs);
+		if (ret == IRQ_HANDLED)
+			status |= action->flags;
+		retval |= ret;
+		action = action->next;
+	} while (action);
+
+	if (status & SA_SAMPLE_RANDOM)
+		add_interrupt_randomness(irq);
+	local_irq_disable();
+
+	return retval;
+}
+
+/*
+ * do_IRQ handles all normal device IRQ's (the special
+ * SMP cross-CPU interrupts have their own specific
+ * handlers).
+ */
+fastcall unsigned int __do_IRQ(unsigned int irq, struct pt_regs *regs)
+{
+	irq_desc_t *desc = irq_desc + irq;
+	struct irqaction * action;
+	unsigned int status;
+
+	kstat_this_cpu.irqs[irq]++;
+	if (desc->status & IRQ_PER_CPU) {
+		irqreturn_t action_ret;
+
+		/*
+		 * No locking required for CPU-local interrupts:
+		 */
+		desc->handler->ack(irq);
+		action_ret = handle_IRQ_event(irq, regs, desc->action);
+		if (!noirqdebug)
+			note_interrupt(irq, desc, action_ret);
+		desc->handler->end(irq);
+		return 1;
+	}
+
+	spin_lock(&desc->lock);
+	desc->handler->ack(irq);
+	/*
+	 * REPLAY is when Linux resends an IRQ that was dropped earlier
+	 * WAITING is used by probe to mark irqs that are being tested
+	 */
+	status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
+	status |= IRQ_PENDING; /* we _want_ to handle it */
+
+	/*
+	 * If the IRQ is disabled for whatever reason, we cannot
+	 * use the action we have.
+	 */
+	action = NULL;
+	if (likely(!(status & (IRQ_DISABLED | IRQ_INPROGRESS)))) {
+		action = desc->action;
+		status &= ~IRQ_PENDING; /* we commit to handling */
+		status |= IRQ_INPROGRESS; /* we are handling it */
+	}
+	desc->status = status;
+
+	/*
+	 * If there is no IRQ handler or it was disabled, exit early.
+	 * Since we set PENDING, if another processor is handling
+	 * a different instance of this same irq, the other processor
+	 * will take care of it.
+	 */
+	if (unlikely(!action))
+		goto out;
+
+	/*
+	 * Edge triggered interrupts need to remember
+	 * pending events.
+	 * This applies to any hw interrupts that allow a second
+	 * instance of the same irq to arrive while we are in do_IRQ
+	 * or in the handler. But the code here only handles the _second_
+	 * instance of the irq, not the third or fourth. So it is mostly
+	 * useful for irq hardware that does not mask cleanly in an
+	 * SMP environment.
+	 */
+	for (;;) {
+		irqreturn_t action_ret;
+
+		spin_unlock(&desc->lock);
+
+		action_ret = handle_IRQ_event(irq, regs, action);
+
+		spin_lock(&desc->lock);
+		if (!noirqdebug)
+			note_interrupt(irq, desc, action_ret);
+		if (likely(!(desc->status & IRQ_PENDING)))
+			break;
+		desc->status &= ~IRQ_PENDING;
+	}
+	desc->status &= ~IRQ_INPROGRESS;
+
+out:
+	/*
+	 * The ->end() handler has to deal with interrupts which got
+	 * disabled while the handler was running.
+	 */
+	desc->handler->end(irq);
+	spin_unlock(&desc->lock);
+
+	return 1;
+}
+