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authorAlan Cox <alan@lxorguk.ukuu.org.uk>2007-07-16 02:40:55 -0400
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-16 12:05:46 -0400
commit4f27c00bf80f122513d3a5be16ed851573164534 (patch)
tree2abad49c1e5c93d2d8698c558eb490b99bd35b87
parentf3dc8c189a20dc5d115b8f0d07ac620e69eff05c (diff)
Improve behaviour of spurious IRQ detect
Currently we handle spurious IRQ activity based upon seeing a lot of invalid interrupts, and we clear things back on the base of lots of valid interrupts. Unfortunately in some cases you get legitimate invalid interrupts caused by timing asynchronicity between the PCI bus and the APIC bus when disabling interrupts and pulling other tricks. In this case although the spurious IRQs are not a problem our unhandled counters didn't clear and they act as a slow running timebomb. (This is effectively what the serial port/tty problem that was fixed by clearing counters when registering a handler showed up) It's easy enough to add a second parameter - time. This means that if we see a regular stream of harmless spurious interrupts which are not harming processing we don't go off and do something stupid like disable the IRQ after a month of running. OTOH lockups and performance killers show up a lot more than 10/second [akpm@linux-foundation.org: cleanup] Signed-off-by: Alan Cox <alan@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/irq.h1
-rw-r--r--kernel/irq/spurious.c12
2 files changed, 12 insertions, 1 deletions
diff --git a/include/linux/irq.h b/include/linux/irq.h
index 1695054e8c63..44657197fcb0 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -161,6 +161,7 @@ struct irq_desc {
161 unsigned int wake_depth; /* nested wake enables */ 161 unsigned int wake_depth; /* nested wake enables */
162 unsigned int irq_count; /* For detecting broken IRQs */ 162 unsigned int irq_count; /* For detecting broken IRQs */
163 unsigned int irqs_unhandled; 163 unsigned int irqs_unhandled;
164 unsigned long last_unhandled; /* Aging timer for unhandled count */
164 spinlock_t lock; 165 spinlock_t lock;
165#ifdef CONFIG_SMP 166#ifdef CONFIG_SMP
166 cpumask_t affinity; 167 cpumask_t affinity;
diff --git a/kernel/irq/spurious.c b/kernel/irq/spurious.c
index bd9e272d55e9..32b161972fad 100644
--- a/kernel/irq/spurious.c
+++ b/kernel/irq/spurious.c
@@ -172,7 +172,17 @@ void note_interrupt(unsigned int irq, struct irq_desc *desc,
172 irqreturn_t action_ret) 172 irqreturn_t action_ret)
173{ 173{
174 if (unlikely(action_ret != IRQ_HANDLED)) { 174 if (unlikely(action_ret != IRQ_HANDLED)) {
175 desc->irqs_unhandled++; 175 /*
176 * If we are seeing only the odd spurious IRQ caused by
177 * bus asynchronicity then don't eventually trigger an error,
178 * otherwise the couter becomes a doomsday timer for otherwise
179 * working systems
180 */
181 if (jiffies - desc->last_unhandled > HZ/10)
182 desc->irqs_unhandled = 1;
183 else
184 desc->irqs_unhandled++;
185 desc->last_unhandled = jiffies;
176 if (unlikely(action_ret != IRQ_NONE)) 186 if (unlikely(action_ret != IRQ_NONE))
177 report_bad_irq(irq, desc, action_ret); 187 report_bad_irq(irq, desc, action_ret);
178 } 188 }