genirq: Prevent irq storm on migration
[linux-2.6.git] / kernel / irq / migration.c
1
2 #include <linux/irq.h>
3 #include <linux/interrupt.h>
4
5 #include "internals.h"
6
7 void move_masked_irq(int irq)
8 {
9         struct irq_desc *desc = irq_to_desc(irq);
10         struct irq_chip *chip = desc->irq_data.chip;
11
12         if (likely(!(desc->status & IRQ_MOVE_PENDING)))
13                 return;
14
15         /*
16          * Paranoia: cpu-local interrupts shouldn't be calling in here anyway.
17          */
18         if (CHECK_IRQ_PER_CPU(desc->status)) {
19                 WARN_ON(1);
20                 return;
21         }
22
23         desc->status &= ~IRQ_MOVE_PENDING;
24
25         if (unlikely(cpumask_empty(desc->pending_mask)))
26                 return;
27
28         if (!chip->irq_set_affinity)
29                 return;
30
31         assert_raw_spin_locked(&desc->lock);
32
33         /*
34          * If there was a valid mask to work with, please
35          * do the disable, re-program, enable sequence.
36          * This is *not* particularly important for level triggered
37          * but in a edge trigger case, we might be setting rte
38          * when an active trigger is comming in. This could
39          * cause some ioapics to mal-function.
40          * Being paranoid i guess!
41          *
42          * For correct operation this depends on the caller
43          * masking the irqs.
44          */
45         if (likely(cpumask_any_and(desc->pending_mask, cpu_online_mask)
46                    < nr_cpu_ids))
47                 if (!chip->irq_set_affinity(&desc->irq_data,
48                                             desc->pending_mask, false)) {
49                         cpumask_copy(desc->irq_data.affinity, desc->pending_mask);
50                         irq_set_thread_affinity(desc);
51                 }
52
53         cpumask_clear(desc->pending_mask);
54 }
55
56 void move_native_irq(int irq)
57 {
58         struct irq_desc *desc = irq_to_desc(irq);
59         bool masked;
60
61         if (likely(!(desc->status & IRQ_MOVE_PENDING)))
62                 return;
63
64         if (unlikely(desc->status & IRQ_DISABLED))
65                 return;
66
67         /*
68          * Be careful vs. already masked interrupts. If this is a
69          * threaded interrupt with ONESHOT set, we can end up with an
70          * interrupt storm.
71          */
72         masked = desc->status & IRQ_MASKED;
73         if (!masked)
74                 desc->irq_data.chip->irq_mask(&desc->irq_data);
75         move_masked_irq(irq);
76         if (!masked)
77                 desc->irq_data.chip->irq_unmask(&desc->irq_data);
78 }