irq: replace loop with nr_irqs with for_each_irq_desc

There are a handful of loops that go from 0 to nr_irqs and use
get_irq_desc() on them. These would allocate all the irq_desc
entries, regardless of the need for them.

Use the smarter for_each_irq_desc() iterator that will only iterate
over the present ones.

v2: make sure arch without GENERIC_HARDIRQS work too

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/kernel/io_apic_64.c b/arch/x86/kernel/io_apic_64.c
index 51ef7eb..708be97 100644 (file)
--- a/arch/x86/kernel/io_apic_64.c
+++ b/arch/x86/kernel/io_apic_64.c
@@ -1871,10 +1871,10 @@ unmask:
 
 static void ir_irq_migration(struct work_struct *work)
 {
-       int irq;
+       unsigned int irq;
+       struct irq_desc *desc;
 
-       for (irq = 0; irq < nr_irqs; irq++) {
-               struct irq_desc *desc = irq_to_desc(irq);
+       for_each_irq_desc(irq, desc) {
                if (desc->status & IRQ_MOVE_PENDING) {
                        unsigned long flags;
 

diff --git a/arch/x86/kernel/irq_64.c b/arch/x86/kernel/irq_64.c
index 4a0a4eb..b3cf55e 100644 (file)
--- a/arch/x86/kernel/irq_64.c
+++ b/arch/x86/kernel/irq_64.c
@@ -224,17 +224,16 @@ void fixup_irqs(cpumask_t map)
 {
        unsigned int irq;
        static int warned;
+       struct irq_desc *desc;
 
-       for (irq = 0; irq < nr_irqs; irq++) {
+       for_each_irq_desc(irq, desc) {
                cpumask_t mask;
                int break_affinity = 0;
                int set_affinity = 1;
-               struct irq_desc *desc;
 
                if (irq == 2)
                        continue;
 
-               desc = irq_to_desc(irq);
                /* interrupt's are disabled at this point */
                spin_lock(&desc->lock);
 

diff --git a/arch/x86/kernel/irqinit_64.c b/arch/x86/kernel/irqinit_64.c
index 0744b49..cd9f42d 100644 (file)
--- a/arch/x86/kernel/irqinit_64.c
+++ b/arch/x86/kernel/irqinit_64.c
@@ -142,25 +142,18 @@ void __init init_ISA_irqs(void)
        init_bsp_APIC();
        init_8259A(0);
 
-       for (i = 0; i < nr_irqs; i++) {
+       for (i = 0; i < 16; i++) {
                struct irq_desc *desc = irq_to_desc(i);
 
                desc->status = IRQ_DISABLED;
                desc->action = NULL;
                desc->depth = 1;
 
-               if (i < 16) {
-                       /*
-                        * 16 old-style INTA-cycle interrupts:
-                        */
-                       set_irq_chip_and_handler_name(i, &i8259A_chip,
+               /*
+                * 16 old-style INTA-cycle interrupts:
+                */
+               set_irq_chip_and_handler_name(i, &i8259A_chip,
                                                      handle_level_irq, "XT");
-               } else {
-                       /*
-                        * 'high' PCI IRQs filled in on demand
-                        */
-                       desc->chip = &no_irq_chip;
-               }
        }
 }
 

diff --git a/include/linux/irq.h b/include/linux/irq.h
index c9ffef7..9de16ca 100644 (file)
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -202,9 +202,16 @@ extern struct irq_desc irq_desc[NR_IRQS];
 extern struct irq_desc *irq_desc;
 #endif
 
+#ifdef CONFIG_GENERIC_HARDIRQS
+#define for_each_irq_desc(irq, desc)           \
+       for (irq = 0, desc = irq_desc; irq < nr_irqs; irq++, desc = &irq_desc[irq])
+#endif
+
 #else
 
 extern struct irq_desc *sparse_irqs;
+#define for_each_irq_desc(irqX, desc)          \
+       for (desc = sparse_irqs, irqX = desc->irq; desc && irqX != -1U; desc = desc->next, irqX = desc ? desc->irq : -1U)
 
 #endif
 

diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h
index 422dd00..c9767e6 100644 (file)
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -14,11 +14,11 @@ extern int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
                unsigned long flags);
 
 #ifdef CONFIG_PROC_FS
-extern void register_irq_proc(unsigned int irq);
+extern void register_irq_proc(unsigned int irq, struct irq_desc *desc);
 extern void register_handler_proc(unsigned int irq, struct irqaction *action);
 extern void unregister_handler_proc(unsigned int irq, struct irqaction *action);
 #else
-static inline void register_irq_proc(unsigned int irq) { }
+static inline void register_irq_proc(unsigned int irq, struct irq_desc *desc) { }
 static inline void register_handler_proc(unsigned int irq,
                                         struct irqaction *action) { }
 static inline void unregister_handler_proc(unsigned int irq,

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index b5943e9..5070f55 100644 (file)
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -478,7 +478,7 @@ int setup_irq(unsigned int irq, struct irqaction *new)
        spin_unlock_irqrestore(&desc->lock, flags);
 
        new->irq = irq;
-       register_irq_proc(irq);
+       register_irq_proc(irq, desc);
        new->dir = NULL;
        register_handler_proc(irq, new);
 

diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c
index c2f356c..bc0993d 100644 (file)
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -182,11 +182,10 @@ void register_handler_proc(unsigned int irq, struct irqaction *action)
 
 #define MAX_NAMELEN 10
 
-void register_irq_proc(unsigned int irq)
+void register_irq_proc(unsigned int irq, struct irq_desc *desc)
 {
        char name [MAX_NAMELEN];
        struct proc_dir_entry *entry;
-       struct irq_desc *desc = irq_to_desc(irq);
 
        if (!root_irq_dir || (desc->chip == &no_irq_chip) || desc->dir)
                return;
@@ -230,7 +229,8 @@ void register_default_affinity_proc(void)
 
 void init_irq_proc(void)
 {
-       int i;
+       unsigned int irq;
+       struct irq_desc *desc;
 
        /* create /proc/irq */
        root_irq_dir = proc_mkdir("irq", NULL);
@@ -242,7 +242,7 @@ void init_irq_proc(void)
        /*
         * Create entries for all existing IRQs.
         */
-       for (i = 0; i < nr_irqs; i++)
-               register_irq_proc(i);
+       for_each_irq_desc(irq, desc)
+               register_irq_proc(irq, desc);
 }