PATCH: 2.6.10 - Misrouted IRQ recovery for review

From: Alan Cox
Date: Tue Dec 28 2004 - 12:03:59 EST


Ported to the new kernel/irq code.

diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.10/kernel/irq/handle.c linux-2.6.10/kernel/irq/handle.c
--- linux.vanilla-2.6.10/kernel/irq/handle.c 2004-12-25 21:15:46.000000000 +0000
+++ linux-2.6.10/kernel/irq/handle.c 2004-12-26 23:20:04.000000000 +0000
@@ -130,7 +130,7 @@
desc->handler->ack(irq);
action_ret = handle_IRQ_event(irq, regs, desc->action);
if (!noirqdebug)
- note_interrupt(irq, desc, action_ret);
+ note_interrupt(irq, desc, action_ret, regs);
desc->handler->end(irq);
return 1;
}
@@ -184,7 +184,7 @@

spin_lock(&desc->lock);
if (!noirqdebug)
- note_interrupt(irq, desc, action_ret);
+ note_interrupt(irq, desc, action_ret, regs);
if (likely(!(desc->status & IRQ_PENDING)))
break;
desc->status &= ~IRQ_PENDING;
diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.10/kernel/irq/spurious.c linux-2.6.10/kernel/irq/spurious.c
--- linux.vanilla-2.6.10/kernel/irq/spurious.c 2004-12-25 21:15:46.000000000 +0000
+++ linux-2.6.10/kernel/irq/spurious.c 2004-12-26 23:26:55.000000000 +0000
@@ -11,6 +11,77 @@
#include <linux/kallsyms.h>
#include <linux/interrupt.h>

+static int irqfixup;
+
+/*
+ * Recovery handler for misrouted interrupts.
+ */
+
+static int misrouted_irq(int irq, struct pt_regs *regs)
+{
+ int i;
+ irq_desc_t *desc;
+ int ok = 0;
+ int work = 0; /* Did we do work for a real IRQ */
+ for(i = 1; i < NR_IRQS; i++)
+ {
+ struct irqaction *action;
+ if(i == irq) /* Already tried */
+ continue;
+ desc = &irq_desc[i];
+ spin_lock(&desc->lock);
+ action = desc->action;
+ /* Already running on another processor */
+ if(desc->status & IRQ_INPROGRESS)
+ {
+ /* Already running: If it is shared get the other
+ CPU to go looking for our mystery interrupt too */
+ if(desc->action && (desc->action->flags & SA_SHIRQ))
+ desc->status |= IRQ_PENDING;
+ spin_unlock(&desc->lock);
+ continue;
+ }
+ /* Honour the normal IRQ locking */
+ desc->status |= IRQ_INPROGRESS;
+ spin_unlock(&desc->lock);
+ while(action)
+ {
+ /* Only shared IRQ handlers are safe to call */
+ if(action->flags & SA_SHIRQ)
+ {
+ if(action->handler(i, action->dev_id, regs) == IRQ_HANDLED)
+ ok = 1;
+ }
+ action = action->next;
+ }
+ local_irq_disable();
+ /* Now clean up the flags */
+ spin_lock(&desc->lock);
+ action = desc->action;
+
+ /* While we were looking for a fixup someone queued a real
+ IRQ clashing with our walk */
+
+ while((desc->status & IRQ_PENDING) && action)
+ {
+ /* Perform real IRQ processing for the IRQ we deferred */
+ work = 1;
+ spin_unlock(&desc->lock);
+ handle_IRQ_event(i, regs, action);
+ spin_lock(&desc->lock);
+ desc->status &= ~IRQ_PENDING;
+ }
+ desc->status &= ~IRQ_INPROGRESS;
+ /* If we did actual work for the real IRQ line we must
+ let the IRQ controller clean up too */
+ if(work)
+ desc->handler->end(i);
+ spin_unlock(&desc->lock);
+ }
+ /* So the caller can adjust the irq error counts */
+ return ok;
+}
+
/*
* If 99,900 of the previous 100,000 interrupts have not been handled
* then assume that the IRQ is stuck in some manner. Drop a diagnostic
@@ -31,7 +102,7 @@
printk(KERN_ERR "irq event %d: bogus return value %x\n",
irq, action_ret);
} else {
- printk(KERN_ERR "irq %d: nobody cared!\n", irq);
+ printk(KERN_ERR "irq %d: nobody cared (try booting with the \"irqpoll\" option.\n", irq);
}
dump_stack();
printk(KERN_ERR "handlers:\n");
@@ -55,7 +126,7 @@
}
}

-void note_interrupt(unsigned int irq, irq_desc_t *desc, irqreturn_t action_ret)
+void note_interrupt(unsigned int irq, irq_desc_t *desc, irqreturn_t action_ret, struct pt_regs *regs)
{
if (action_ret != IRQ_HANDLED) {
desc->irqs_unhandled++;
@@ -63,6 +134,15 @@
report_bad_irq(irq, desc, action_ret);
}

+ if(unlikely(irqfixup)) { /* Don't punish working computers */
+ if((irqfixup == 2 && irq == 0) || action_ret == IRQ_NONE) {
+ int ok;
+ ok = misrouted_irq(irq, regs);
+ if(action_ret == IRQ_NONE)
+ desc->irqs_unhandled -= ok;
+ }
+ }
+
desc->irq_count++;
if (desc->irq_count < 100000)
return;
@@ -94,3 +174,22 @@

__setup("noirqdebug", noirqdebug_setup);

+static int __init irqfixup_setup(char *str)
+{
+ irqfixup = 1;
+ printk(KERN_WARNING "Misrouted IRQ fixup support enabled.\n");
+ printk(KERN_WARNING "This may impact system performance.\n");
+ return 1;
+}
+
+__setup("irqfixup", irqfixup_setup);
+
+static int __init irqpoll_setup(char *str)
+{
+ irqfixup = 2;
+ printk(KERN_WARNING "Misrouted IRQ fixup and polling support enabled.\n");
+ printk(KERN_WARNING "This may significantly impact system performance.\n");
+ return 1;
+}
+
+__setup("irqpoll", irqpoll_setup);

-
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