sparse irq_desc[] array: core kernel and x86 changes
Impact: new feature
Problem on distro kernels: irq_desc[NR_IRQS] takes megabytes of RAM with
NR_CPUS set to large values. The goal is to be able to scale up to much
larger NR_IRQS value without impacting the (important) common case.
To solve this, we generalize irq_desc[NR_IRQS] to an (optional) array of
irq_desc pointers.
When CONFIG_SPARSE_IRQ=y is used, we use kzalloc_node to get irq_desc,
this also makes the IRQ descriptors NUMA-local (to the site that calls
request_irq()).
This gets rid of the irq_cfg[] static array on x86 as well: irq_cfg now
uses desc->chip_data for x86 to store irq_cfg.
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/irq/autoprobe.c b/kernel/irq/autoprobe.c
index cc0f732..650ce41 100644
--- a/kernel/irq/autoprobe.c
+++ b/kernel/irq/autoprobe.c
@@ -40,6 +40,9 @@
* flush such a longstanding irq before considering it as spurious.
*/
for_each_irq_desc_reverse(i, desc) {
+ if (!desc)
+ continue;
+
spin_lock_irq(&desc->lock);
if (!desc->action && !(desc->status & IRQ_NOPROBE)) {
/*
@@ -68,6 +71,9 @@
* happened in the previous stage, it may have masked itself)
*/
for_each_irq_desc_reverse(i, desc) {
+ if (!desc)
+ continue;
+
spin_lock_irq(&desc->lock);
if (!desc->action && !(desc->status & IRQ_NOPROBE)) {
desc->status |= IRQ_AUTODETECT | IRQ_WAITING;
@@ -86,6 +92,9 @@
* Now filter out any obviously spurious interrupts
*/
for_each_irq_desc(i, desc) {
+ if (!desc)
+ continue;
+
spin_lock_irq(&desc->lock);
status = desc->status;
@@ -124,6 +133,9 @@
int i;
for_each_irq_desc(i, desc) {
+ if (!desc)
+ continue;
+
spin_lock_irq(&desc->lock);
status = desc->status;
@@ -166,6 +178,9 @@
unsigned int status;
for_each_irq_desc(i, desc) {
+ if (!desc)
+ continue;
+
spin_lock_irq(&desc->lock);
status = desc->status;