Fix possible runqueue lock starvation in wait_task_inactive()
[linux-2.6] / kernel / irq / migration.c
1
2 #include <linux/irq.h>
3
4 void set_pending_irq(unsigned int irq, cpumask_t mask)
5 {
6         struct irq_desc *desc = irq_desc + irq;
7         unsigned long flags;
8
9         spin_lock_irqsave(&desc->lock, flags);
10         desc->status |= IRQ_MOVE_PENDING;
11         irq_desc[irq].pending_mask = mask;
12         spin_unlock_irqrestore(&desc->lock, flags);
13 }
14
15 void move_masked_irq(int irq)
16 {
17         struct irq_desc *desc = irq_desc + irq;
18         cpumask_t tmp;
19
20         if (likely(!(desc->status & IRQ_MOVE_PENDING)))
21                 return;
22
23         /*
24          * Paranoia: cpu-local interrupts shouldn't be calling in here anyway.
25          */
26         if (CHECK_IRQ_PER_CPU(desc->status)) {
27                 WARN_ON(1);
28                 return;
29         }
30
31         desc->status &= ~IRQ_MOVE_PENDING;
32
33         if (unlikely(cpus_empty(irq_desc[irq].pending_mask)))
34                 return;
35
36         if (!desc->chip->set_affinity)
37                 return;
38
39         assert_spin_locked(&desc->lock);
40
41         cpus_and(tmp, irq_desc[irq].pending_mask, cpu_online_map);
42
43         /*
44          * If there was a valid mask to work with, please
45          * do the disable, re-program, enable sequence.
46          * This is *not* particularly important for level triggered
47          * but in a edge trigger case, we might be setting rte
48          * when an active trigger is comming in. This could
49          * cause some ioapics to mal-function.
50          * Being paranoid i guess!
51          *
52          * For correct operation this depends on the caller
53          * masking the irqs.
54          */
55         if (likely(!cpus_empty(tmp))) {
56                 desc->chip->set_affinity(irq,tmp);
57         }
58         cpus_clear(irq_desc[irq].pending_mask);
59 }
60
61 void move_native_irq(int irq)
62 {
63         struct irq_desc *desc = irq_desc + irq;
64
65         if (likely(!(desc->status & IRQ_MOVE_PENDING)))
66                 return;
67
68         if (unlikely(desc->status & IRQ_DISABLED))
69                 return;
70
71         desc->chip->mask(irq);
72         move_masked_irq(irq);
73         desc->chip->unmask(irq);
74 }
75