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/include/linux/random.h b/include/linux/random.h
index 36f125c..ad9daa2 100644
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -44,6 +44,57 @@
extern void rand_initialize_irq(int irq);
+struct timer_rand_state;
+#ifndef CONFIG_SPARSE_IRQ
+
+extern struct timer_rand_state *irq_timer_state[];
+
+extern int nr_irqs;
+static inline struct timer_rand_state *get_timer_rand_state(unsigned int irq)
+{
+ if (irq >= nr_irqs)
+ return NULL;
+
+ return irq_timer_state[irq];
+}
+
+static inline void set_timer_rand_state(unsigned int irq, struct timer_rand_state *state)
+{
+ if (irq >= nr_irqs)
+ return;
+
+ irq_timer_state[irq] = state;
+}
+
+#else
+
+#include <linux/irq.h>
+static inline struct timer_rand_state *get_timer_rand_state(unsigned int irq)
+{
+ struct irq_desc *desc;
+
+ desc = irq_to_desc(irq);
+
+ if (!desc)
+ return NULL;
+
+ return desc->timer_rand_state;
+}
+
+static inline void set_timer_rand_state(unsigned int irq, struct timer_rand_state *state)
+{
+ struct irq_desc *desc;
+
+ desc = irq_to_desc(irq);
+
+ if (!desc)
+ return;
+
+ desc->timer_rand_state = state;
+}
+#endif
+
+
extern void add_input_randomness(unsigned int type, unsigned int code,
unsigned int value);
extern void add_interrupt_randomness(int irq);