sparseirq: fix numa_migrate_irq_desc dependency and comments
[linux-2.6.git] / kernel / irq / numa_migrate.c
1 /*
2  * NUMA irq-desc migration code
3  *
4  * Migrate IRQ data structures (irq_desc, chip_data, etc.) over to
5  * the new "home node" of the IRQ.
6  */
7
8 #include <linux/irq.h>
9 #include <linux/module.h>
10 #include <linux/random.h>
11 #include <linux/interrupt.h>
12 #include <linux/kernel_stat.h>
13
14 #include "internals.h"
15
16 static void init_copy_kstat_irqs(struct irq_desc *old_desc,
17                                  struct irq_desc *desc,
18                                  int cpu, int nr)
19 {
20         unsigned long bytes;
21
22         init_kstat_irqs(desc, cpu, nr);
23
24         if (desc->kstat_irqs != old_desc->kstat_irqs) {
25                 /* Compute how many bytes we need per irq and allocate them */
26                 bytes = nr * sizeof(unsigned int);
27
28                 memcpy(desc->kstat_irqs, old_desc->kstat_irqs, bytes);
29         }
30 }
31
32 static void free_kstat_irqs(struct irq_desc *old_desc, struct irq_desc *desc)
33 {
34         if (old_desc->kstat_irqs == desc->kstat_irqs)
35                 return;
36
37         kfree(old_desc->kstat_irqs);
38         old_desc->kstat_irqs = NULL;
39 }
40
41 static void init_copy_one_irq_desc(int irq, struct irq_desc *old_desc,
42                  struct irq_desc *desc, int cpu)
43 {
44         memcpy(desc, old_desc, sizeof(struct irq_desc));
45         desc->cpu = cpu;
46         lockdep_set_class(&desc->lock, &irq_desc_lock_class);
47         init_copy_kstat_irqs(old_desc, desc, cpu, nr_cpu_ids);
48         arch_init_copy_chip_data(old_desc, desc, cpu);
49 }
50
51 static void free_one_irq_desc(struct irq_desc *old_desc, struct irq_desc *desc)
52 {
53         free_kstat_irqs(old_desc, desc);
54         arch_free_chip_data(old_desc, desc);
55 }
56
57 static struct irq_desc *__real_move_irq_desc(struct irq_desc *old_desc,
58                                                 int cpu)
59 {
60         struct irq_desc *desc;
61         unsigned int irq;
62         unsigned long flags;
63         int node;
64
65         irq = old_desc->irq;
66
67         spin_lock_irqsave(&sparse_irq_lock, flags);
68
69         /* We have to check it to avoid races with another CPU */
70         desc = irq_desc_ptrs[irq];
71
72         if (desc && old_desc != desc)
73                         goto out_unlock;
74
75         node = cpu_to_node(cpu);
76         desc = kzalloc_node(sizeof(*desc), GFP_ATOMIC, node);
77         printk(KERN_DEBUG "  move irq_desc for %d to cpu %d node %d\n",
78                  irq, cpu, node);
79         if (!desc) {
80                 printk(KERN_ERR "can not get new irq_desc for moving\n");
81                 /* still use old one */
82                 desc = old_desc;
83                 goto out_unlock;
84         }
85         init_copy_one_irq_desc(irq, old_desc, desc, cpu);
86
87         irq_desc_ptrs[irq] = desc;
88
89         /* free the old one */
90         free_one_irq_desc(old_desc, desc);
91         kfree(old_desc);
92
93 out_unlock:
94         spin_unlock_irqrestore(&sparse_irq_lock, flags);
95
96         return desc;
97 }
98
99 struct irq_desc *move_irq_desc(struct irq_desc *desc, int cpu)
100 {
101         int old_cpu;
102         int node, old_node;
103
104         /* those all static, do move them */
105         if (desc->irq < NR_IRQS_LEGACY)
106                 return desc;
107
108         old_cpu = desc->cpu;
109         printk(KERN_DEBUG
110                  "try to move irq_desc from cpu %d to %d\n", old_cpu, cpu);
111         if (old_cpu != cpu) {
112                 node = cpu_to_node(cpu);
113                 old_node = cpu_to_node(old_cpu);
114                 if (old_node != node)
115                         desc = __real_move_irq_desc(desc, cpu);
116                 else
117                         desc->cpu = cpu;
118         }
119
120         return desc;
121 }
122