genirq: Delegate irq affinity setting to the irq thread
[linux-2.6.git] / kernel / irq / manage.c
1 /*
2  * linux/kernel/irq/manage.c
3  *
4  * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
5  * Copyright (C) 2005-2006 Thomas Gleixner
6  *
7  * This file contains driver APIs to the irq subsystem.
8  */
9
10 #include <linux/irq.h>
11 #include <linux/kthread.h>
12 #include <linux/module.h>
13 #include <linux/random.h>
14 #include <linux/interrupt.h>
15 #include <linux/slab.h>
16 #include <linux/sched.h>
17
18 #include "internals.h"
19
20 /**
21  *      synchronize_irq - wait for pending IRQ handlers (on other CPUs)
22  *      @irq: interrupt number to wait for
23  *
24  *      This function waits for any pending IRQ handlers for this interrupt
25  *      to complete before returning. If you use this function while
26  *      holding a resource the IRQ handler may need you will deadlock.
27  *
28  *      This function may be called - with care - from IRQ context.
29  */
30 void synchronize_irq(unsigned int irq)
31 {
32         struct irq_desc *desc = irq_to_desc(irq);
33         unsigned int status;
34
35         if (!desc)
36                 return;
37
38         do {
39                 unsigned long flags;
40
41                 /*
42                  * Wait until we're out of the critical section.  This might
43                  * give the wrong answer due to the lack of memory barriers.
44                  */
45                 while (desc->status & IRQ_INPROGRESS)
46                         cpu_relax();
47
48                 /* Ok, that indicated we're done: double-check carefully. */
49                 spin_lock_irqsave(&desc->lock, flags);
50                 status = desc->status;
51                 spin_unlock_irqrestore(&desc->lock, flags);
52
53                 /* Oops, that failed? */
54         } while (status & IRQ_INPROGRESS);
55
56         /*
57          * We made sure that no hardirq handler is running. Now verify
58          * that no threaded handlers are active.
59          */
60         wait_event(desc->wait_for_threads, !atomic_read(&desc->threads_active));
61 }
62 EXPORT_SYMBOL(synchronize_irq);
63
64 #ifdef CONFIG_SMP
65 cpumask_var_t irq_default_affinity;
66
67 /**
68  *      irq_can_set_affinity - Check if the affinity of a given irq can be set
69  *      @irq:           Interrupt to check
70  *
71  */
72 int irq_can_set_affinity(unsigned int irq)
73 {
74         struct irq_desc *desc = irq_to_desc(irq);
75
76         if (CHECK_IRQ_PER_CPU(desc->status) || !desc->chip ||
77             !desc->chip->set_affinity)
78                 return 0;
79
80         return 1;
81 }
82
83 /**
84  *      irq_set_thread_affinity - Notify irq threads to adjust affinity
85  *      @desc:          irq descriptor which has affitnity changed
86  *
87  *      We just set IRQTF_AFFINITY and delegate the affinity setting
88  *      to the interrupt thread itself. We can not call
89  *      set_cpus_allowed_ptr() here as we hold desc->lock and this
90  *      code can be called from hard interrupt context.
91  */
92 void irq_set_thread_affinity(struct irq_desc *desc)
93 {
94         struct irqaction *action = desc->action;
95
96         while (action) {
97                 if (action->thread)
98                         set_bit(IRQTF_AFFINITY, &action->thread_flags);
99                 action = action->next;
100         }
101 }
102
103 /**
104  *      irq_set_affinity - Set the irq affinity of a given irq
105  *      @irq:           Interrupt to set affinity
106  *      @cpumask:       cpumask
107  *
108  */
109 int irq_set_affinity(unsigned int irq, const struct cpumask *cpumask)
110 {
111         struct irq_desc *desc = irq_to_desc(irq);
112         unsigned long flags;
113
114         if (!desc->chip->set_affinity)
115                 return -EINVAL;
116
117         spin_lock_irqsave(&desc->lock, flags);
118
119 #ifdef CONFIG_GENERIC_PENDING_IRQ
120         if (desc->status & IRQ_MOVE_PCNTXT) {
121                 if (!desc->chip->set_affinity(irq, cpumask)) {
122                         cpumask_copy(desc->affinity, cpumask);
123                         irq_set_thread_affinity(desc);
124                 }
125         }
126         else {
127                 desc->status |= IRQ_MOVE_PENDING;
128                 cpumask_copy(desc->pending_mask, cpumask);
129         }
130 #else
131         if (!desc->chip->set_affinity(irq, cpumask)) {
132                 cpumask_copy(desc->affinity, cpumask);
133                 irq_set_thread_affinity(desc);
134         }
135 #endif
136         desc->status |= IRQ_AFFINITY_SET;
137         spin_unlock_irqrestore(&desc->lock, flags);
138         return 0;
139 }
140
141 #ifndef CONFIG_AUTO_IRQ_AFFINITY
142 /*
143  * Generic version of the affinity autoselector.
144  */
145 static int setup_affinity(unsigned int irq, struct irq_desc *desc)
146 {
147         if (!irq_can_set_affinity(irq))
148                 return 0;
149
150         /*
151          * Preserve an userspace affinity setup, but make sure that
152          * one of the targets is online.
153          */
154         if (desc->status & (IRQ_AFFINITY_SET | IRQ_NO_BALANCING)) {
155                 if (cpumask_any_and(desc->affinity, cpu_online_mask)
156                     < nr_cpu_ids)
157                         goto set_affinity;
158                 else
159                         desc->status &= ~IRQ_AFFINITY_SET;
160         }
161
162         cpumask_and(desc->affinity, cpu_online_mask, irq_default_affinity);
163 set_affinity:
164         desc->chip->set_affinity(irq, desc->affinity);
165
166         return 0;
167 }
168 #else
169 static inline int setup_affinity(unsigned int irq, struct irq_desc *d)
170 {
171         return irq_select_affinity(irq);
172 }
173 #endif
174
175 /*
176  * Called when affinity is set via /proc/irq
177  */
178 int irq_select_affinity_usr(unsigned int irq)
179 {
180         struct irq_desc *desc = irq_to_desc(irq);
181         unsigned long flags;
182         int ret;
183
184         spin_lock_irqsave(&desc->lock, flags);
185         ret = setup_affinity(irq, desc);
186         if (!ret)
187                 irq_set_thread_affinity(desc);
188         spin_unlock_irqrestore(&desc->lock, flags);
189
190         return ret;
191 }
192
193 #else
194 static inline int setup_affinity(unsigned int irq, struct irq_desc *desc)
195 {
196         return 0;
197 }
198 #endif
199
200 void __disable_irq(struct irq_desc *desc, unsigned int irq, bool suspend)
201 {
202         if (suspend) {
203                 if (!desc->action || (desc->action->flags & IRQF_TIMER))
204                         return;
205                 desc->status |= IRQ_SUSPENDED;
206         }
207
208         if (!desc->depth++) {
209                 desc->status |= IRQ_DISABLED;
210                 desc->chip->disable(irq);
211         }
212 }
213
214 /**
215  *      disable_irq_nosync - disable an irq without waiting
216  *      @irq: Interrupt to disable
217  *
218  *      Disable the selected interrupt line.  Disables and Enables are
219  *      nested.
220  *      Unlike disable_irq(), this function does not ensure existing
221  *      instances of the IRQ handler have completed before returning.
222  *
223  *      This function may be called from IRQ context.
224  */
225 void disable_irq_nosync(unsigned int irq)
226 {
227         struct irq_desc *desc = irq_to_desc(irq);
228         unsigned long flags;
229
230         if (!desc)
231                 return;
232
233         spin_lock_irqsave(&desc->lock, flags);
234         __disable_irq(desc, irq, false);
235         spin_unlock_irqrestore(&desc->lock, flags);
236 }
237 EXPORT_SYMBOL(disable_irq_nosync);
238
239 /**
240  *      disable_irq - disable an irq and wait for completion
241  *      @irq: Interrupt to disable
242  *
243  *      Disable the selected interrupt line.  Enables and Disables are
244  *      nested.
245  *      This function waits for any pending IRQ handlers for this interrupt
246  *      to complete before returning. If you use this function while
247  *      holding a resource the IRQ handler may need you will deadlock.
248  *
249  *      This function may be called - with care - from IRQ context.
250  */
251 void disable_irq(unsigned int irq)
252 {
253         struct irq_desc *desc = irq_to_desc(irq);
254
255         if (!desc)
256                 return;
257
258         disable_irq_nosync(irq);
259         if (desc->action)
260                 synchronize_irq(irq);
261 }
262 EXPORT_SYMBOL(disable_irq);
263
264 void __enable_irq(struct irq_desc *desc, unsigned int irq, bool resume)
265 {
266         if (resume)
267                 desc->status &= ~IRQ_SUSPENDED;
268
269         switch (desc->depth) {
270         case 0:
271  err_out:
272                 WARN(1, KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
273                 break;
274         case 1: {
275                 unsigned int status = desc->status & ~IRQ_DISABLED;
276
277                 if (desc->status & IRQ_SUSPENDED)
278                         goto err_out;
279                 /* Prevent probing on this irq: */
280                 desc->status = status | IRQ_NOPROBE;
281                 check_irq_resend(desc, irq);
282                 /* fall-through */
283         }
284         default:
285                 desc->depth--;
286         }
287 }
288
289 /**
290  *      enable_irq - enable handling of an irq
291  *      @irq: Interrupt to enable
292  *
293  *      Undoes the effect of one call to disable_irq().  If this
294  *      matches the last disable, processing of interrupts on this
295  *      IRQ line is re-enabled.
296  *
297  *      This function may be called from IRQ context.
298  */
299 void enable_irq(unsigned int irq)
300 {
301         struct irq_desc *desc = irq_to_desc(irq);
302         unsigned long flags;
303
304         if (!desc)
305                 return;
306
307         spin_lock_irqsave(&desc->lock, flags);
308         __enable_irq(desc, irq, false);
309         spin_unlock_irqrestore(&desc->lock, flags);
310 }
311 EXPORT_SYMBOL(enable_irq);
312
313 static int set_irq_wake_real(unsigned int irq, unsigned int on)
314 {
315         struct irq_desc *desc = irq_to_desc(irq);
316         int ret = -ENXIO;
317
318         if (desc->chip->set_wake)
319                 ret = desc->chip->set_wake(irq, on);
320
321         return ret;
322 }
323
324 /**
325  *      set_irq_wake - control irq power management wakeup
326  *      @irq:   interrupt to control
327  *      @on:    enable/disable power management wakeup
328  *
329  *      Enable/disable power management wakeup mode, which is
330  *      disabled by default.  Enables and disables must match,
331  *      just as they match for non-wakeup mode support.
332  *
333  *      Wakeup mode lets this IRQ wake the system from sleep
334  *      states like "suspend to RAM".
335  */
336 int set_irq_wake(unsigned int irq, unsigned int on)
337 {
338         struct irq_desc *desc = irq_to_desc(irq);
339         unsigned long flags;
340         int ret = 0;
341
342         /* wakeup-capable irqs can be shared between drivers that
343          * don't need to have the same sleep mode behaviors.
344          */
345         spin_lock_irqsave(&desc->lock, flags);
346         if (on) {
347                 if (desc->wake_depth++ == 0) {
348                         ret = set_irq_wake_real(irq, on);
349                         if (ret)
350                                 desc->wake_depth = 0;
351                         else
352                                 desc->status |= IRQ_WAKEUP;
353                 }
354         } else {
355                 if (desc->wake_depth == 0) {
356                         WARN(1, "Unbalanced IRQ %d wake disable\n", irq);
357                 } else if (--desc->wake_depth == 0) {
358                         ret = set_irq_wake_real(irq, on);
359                         if (ret)
360                                 desc->wake_depth = 1;
361                         else
362                                 desc->status &= ~IRQ_WAKEUP;
363                 }
364         }
365
366         spin_unlock_irqrestore(&desc->lock, flags);
367         return ret;
368 }
369 EXPORT_SYMBOL(set_irq_wake);
370
371 /*
372  * Internal function that tells the architecture code whether a
373  * particular irq has been exclusively allocated or is available
374  * for driver use.
375  */
376 int can_request_irq(unsigned int irq, unsigned long irqflags)
377 {
378         struct irq_desc *desc = irq_to_desc(irq);
379         struct irqaction *action;
380
381         if (!desc)
382                 return 0;
383
384         if (desc->status & IRQ_NOREQUEST)
385                 return 0;
386
387         action = desc->action;
388         if (action)
389                 if (irqflags & action->flags & IRQF_SHARED)
390                         action = NULL;
391
392         return !action;
393 }
394
395 void compat_irq_chip_set_default_handler(struct irq_desc *desc)
396 {
397         /*
398          * If the architecture still has not overriden
399          * the flow handler then zap the default. This
400          * should catch incorrect flow-type setting.
401          */
402         if (desc->handle_irq == &handle_bad_irq)
403                 desc->handle_irq = NULL;
404 }
405
406 int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
407                 unsigned long flags)
408 {
409         int ret;
410         struct irq_chip *chip = desc->chip;
411
412         if (!chip || !chip->set_type) {
413                 /*
414                  * IRQF_TRIGGER_* but the PIC does not support multiple
415                  * flow-types?
416                  */
417                 pr_debug("No set_type function for IRQ %d (%s)\n", irq,
418                                 chip ? (chip->name ? : "unknown") : "unknown");
419                 return 0;
420         }
421
422         /* caller masked out all except trigger mode flags */
423         ret = chip->set_type(irq, flags);
424
425         if (ret)
426                 pr_err("setting trigger mode %d for irq %u failed (%pF)\n",
427                                 (int)flags, irq, chip->set_type);
428         else {
429                 if (flags & (IRQ_TYPE_LEVEL_LOW | IRQ_TYPE_LEVEL_HIGH))
430                         flags |= IRQ_LEVEL;
431                 /* note that IRQF_TRIGGER_MASK == IRQ_TYPE_SENSE_MASK */
432                 desc->status &= ~(IRQ_LEVEL | IRQ_TYPE_SENSE_MASK);
433                 desc->status |= flags;
434         }
435
436         return ret;
437 }
438
439 static int irq_wait_for_interrupt(struct irqaction *action)
440 {
441         while (!kthread_should_stop()) {
442                 set_current_state(TASK_INTERRUPTIBLE);
443
444                 if (test_and_clear_bit(IRQTF_RUNTHREAD,
445                                        &action->thread_flags)) {
446                         __set_current_state(TASK_RUNNING);
447                         return 0;
448                 }
449                 schedule();
450         }
451         return -1;
452 }
453
454 /*
455  * Check whether we need to change the affinity of the interrupt thread.
456  */
457 static void
458 irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action)
459 {
460         cpumask_var_t mask;
461
462         if (!test_and_clear_bit(IRQTF_AFFINITY, &action->thread_flags))
463                 return;
464
465         /*
466          * In case we are out of memory we set IRQTF_AFFINITY again and
467          * try again next time
468          */
469         if (!alloc_cpumask_var(&mask, GFP_KERNEL)) {
470                 set_bit(IRQTF_AFFINITY, &action->thread_flags);
471                 return;
472         }
473
474         spin_lock_irq(&desc->lock);
475         cpumask_copy(mask, desc->affinity);
476         spin_unlock_irq(&desc->lock);
477
478         set_cpus_allowed_ptr(current, mask);
479         free_cpumask_var(mask);
480 }
481
482 /*
483  * Interrupt handler thread
484  */
485 static int irq_thread(void *data)
486 {
487         struct sched_param param = { .sched_priority = MAX_USER_RT_PRIO/2, };
488         struct irqaction *action = data;
489         struct irq_desc *desc = irq_to_desc(action->irq);
490         int wake;
491
492         sched_setscheduler(current, SCHED_FIFO, &param);
493         current->irqaction = action;
494
495         while (!irq_wait_for_interrupt(action)) {
496
497                 irq_thread_check_affinity(desc, action);
498
499                 atomic_inc(&desc->threads_active);
500
501                 spin_lock_irq(&desc->lock);
502                 if (unlikely(desc->status & IRQ_DISABLED)) {
503                         /*
504                          * CHECKME: We might need a dedicated
505                          * IRQ_THREAD_PENDING flag here, which
506                          * retriggers the thread in check_irq_resend()
507                          * but AFAICT IRQ_PENDING should be fine as it
508                          * retriggers the interrupt itself --- tglx
509                          */
510                         desc->status |= IRQ_PENDING;
511                         spin_unlock_irq(&desc->lock);
512                 } else {
513                         spin_unlock_irq(&desc->lock);
514
515                         action->thread_fn(action->irq, action->dev_id);
516                 }
517
518                 wake = atomic_dec_and_test(&desc->threads_active);
519
520                 if (wake && waitqueue_active(&desc->wait_for_threads))
521                         wake_up(&desc->wait_for_threads);
522         }
523
524         /*
525          * Clear irqaction. Otherwise exit_irq_thread() would make
526          * fuzz about an active irq thread going into nirvana.
527          */
528         current->irqaction = NULL;
529         return 0;
530 }
531
532 /*
533  * Called from do_exit()
534  */
535 void exit_irq_thread(void)
536 {
537         struct task_struct *tsk = current;
538
539         if (!tsk->irqaction)
540                 return;
541
542         printk(KERN_ERR
543                "exiting task \"%s\" (%d) is an active IRQ thread (irq %d)\n",
544                tsk->comm ? tsk->comm : "", tsk->pid, tsk->irqaction->irq);
545
546         /*
547          * Set the THREAD DIED flag to prevent further wakeups of the
548          * soon to be gone threaded handler.
549          */
550         set_bit(IRQTF_DIED, &tsk->irqaction->flags);
551 }
552
553 /*
554  * Internal function to register an irqaction - typically used to
555  * allocate special interrupts that are part of the architecture.
556  */
557 static int
558 __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
559 {
560         struct irqaction *old, **old_ptr;
561         const char *old_name = NULL;
562         unsigned long flags;
563         int shared = 0;
564         int ret;
565
566         if (!desc)
567                 return -EINVAL;
568
569         if (desc->chip == &no_irq_chip)
570                 return -ENOSYS;
571         /*
572          * Some drivers like serial.c use request_irq() heavily,
573          * so we have to be careful not to interfere with a
574          * running system.
575          */
576         if (new->flags & IRQF_SAMPLE_RANDOM) {
577                 /*
578                  * This function might sleep, we want to call it first,
579                  * outside of the atomic block.
580                  * Yes, this might clear the entropy pool if the wrong
581                  * driver is attempted to be loaded, without actually
582                  * installing a new handler, but is this really a problem,
583                  * only the sysadmin is able to do this.
584                  */
585                 rand_initialize_irq(irq);
586         }
587
588         /*
589          * Threaded handler ?
590          */
591         if (new->thread_fn) {
592                 struct task_struct *t;
593
594                 t = kthread_create(irq_thread, new, "irq/%d-%s", irq,
595                                    new->name);
596                 if (IS_ERR(t))
597                         return PTR_ERR(t);
598                 /*
599                  * We keep the reference to the task struct even if
600                  * the thread dies to avoid that the interrupt code
601                  * references an already freed task_struct.
602                  */
603                 get_task_struct(t);
604                 new->thread = t;
605                 wake_up_process(t);
606         }
607
608         /*
609          * The following block of code has to be executed atomically
610          */
611         spin_lock_irqsave(&desc->lock, flags);
612         old_ptr = &desc->action;
613         old = *old_ptr;
614         if (old) {
615                 /*
616                  * Can't share interrupts unless both agree to and are
617                  * the same type (level, edge, polarity). So both flag
618                  * fields must have IRQF_SHARED set and the bits which
619                  * set the trigger type must match.
620                  */
621                 if (!((old->flags & new->flags) & IRQF_SHARED) ||
622                     ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) {
623                         old_name = old->name;
624                         goto mismatch;
625                 }
626
627 #if defined(CONFIG_IRQ_PER_CPU)
628                 /* All handlers must agree on per-cpuness */
629                 if ((old->flags & IRQF_PERCPU) !=
630                     (new->flags & IRQF_PERCPU))
631                         goto mismatch;
632 #endif
633
634                 /* add new interrupt at end of irq queue */
635                 do {
636                         old_ptr = &old->next;
637                         old = *old_ptr;
638                 } while (old);
639                 shared = 1;
640         }
641
642         if (!shared) {
643                 irq_chip_set_defaults(desc->chip);
644
645                 init_waitqueue_head(&desc->wait_for_threads);
646
647                 /* Setup the type (level, edge polarity) if configured: */
648                 if (new->flags & IRQF_TRIGGER_MASK) {
649                         ret = __irq_set_trigger(desc, irq,
650                                         new->flags & IRQF_TRIGGER_MASK);
651
652                         if (ret)
653                                 goto out_thread;
654                 } else
655                         compat_irq_chip_set_default_handler(desc);
656 #if defined(CONFIG_IRQ_PER_CPU)
657                 if (new->flags & IRQF_PERCPU)
658                         desc->status |= IRQ_PER_CPU;
659 #endif
660
661                 desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING |
662                                   IRQ_INPROGRESS | IRQ_SPURIOUS_DISABLED);
663
664                 if (!(desc->status & IRQ_NOAUTOEN)) {
665                         desc->depth = 0;
666                         desc->status &= ~IRQ_DISABLED;
667                         desc->chip->startup(irq);
668                 } else
669                         /* Undo nested disables: */
670                         desc->depth = 1;
671
672                 /* Exclude IRQ from balancing if requested */
673                 if (new->flags & IRQF_NOBALANCING)
674                         desc->status |= IRQ_NO_BALANCING;
675
676                 /* Set default affinity mask once everything is setup */
677                 setup_affinity(irq, desc);
678
679         } else if ((new->flags & IRQF_TRIGGER_MASK)
680                         && (new->flags & IRQF_TRIGGER_MASK)
681                                 != (desc->status & IRQ_TYPE_SENSE_MASK)) {
682                 /* hope the handler works with the actual trigger mode... */
683                 pr_warning("IRQ %d uses trigger mode %d; requested %d\n",
684                                 irq, (int)(desc->status & IRQ_TYPE_SENSE_MASK),
685                                 (int)(new->flags & IRQF_TRIGGER_MASK));
686         }
687
688         *old_ptr = new;
689
690         /* Reset broken irq detection when installing new handler */
691         desc->irq_count = 0;
692         desc->irqs_unhandled = 0;
693
694         /*
695          * Check whether we disabled the irq via the spurious handler
696          * before. Reenable it and give it another chance.
697          */
698         if (shared && (desc->status & IRQ_SPURIOUS_DISABLED)) {
699                 desc->status &= ~IRQ_SPURIOUS_DISABLED;
700                 __enable_irq(desc, irq, false);
701         }
702
703         spin_unlock_irqrestore(&desc->lock, flags);
704
705         new->irq = irq;
706         register_irq_proc(irq, desc);
707         new->dir = NULL;
708         register_handler_proc(irq, new);
709
710         return 0;
711
712 mismatch:
713 #ifdef CONFIG_DEBUG_SHIRQ
714         if (!(new->flags & IRQF_PROBE_SHARED)) {
715                 printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
716                 if (old_name)
717                         printk(KERN_ERR "current handler: %s\n", old_name);
718                 dump_stack();
719         }
720 #endif
721         ret = -EBUSY;
722
723 out_thread:
724         spin_unlock_irqrestore(&desc->lock, flags);
725         if (new->thread) {
726                 struct task_struct *t = new->thread;
727
728                 new->thread = NULL;
729                 if (likely(!test_bit(IRQTF_DIED, &new->thread_flags)))
730                         kthread_stop(t);
731                 put_task_struct(t);
732         }
733         return ret;
734 }
735
736 /**
737  *      setup_irq - setup an interrupt
738  *      @irq: Interrupt line to setup
739  *      @act: irqaction for the interrupt
740  *
741  * Used to statically setup interrupts in the early boot process.
742  */
743 int setup_irq(unsigned int irq, struct irqaction *act)
744 {
745         struct irq_desc *desc = irq_to_desc(irq);
746
747         return __setup_irq(irq, desc, act);
748 }
749 EXPORT_SYMBOL_GPL(setup_irq);
750
751  /*
752  * Internal function to unregister an irqaction - used to free
753  * regular and special interrupts that are part of the architecture.
754  */
755 static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
756 {
757         struct irq_desc *desc = irq_to_desc(irq);
758         struct irqaction *action, **action_ptr;
759         struct task_struct *irqthread;
760         unsigned long flags;
761
762         WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
763
764         if (!desc)
765                 return NULL;
766
767         spin_lock_irqsave(&desc->lock, flags);
768
769         /*
770          * There can be multiple actions per IRQ descriptor, find the right
771          * one based on the dev_id:
772          */
773         action_ptr = &desc->action;
774         for (;;) {
775                 action = *action_ptr;
776
777                 if (!action) {
778                         WARN(1, "Trying to free already-free IRQ %d\n", irq);
779                         spin_unlock_irqrestore(&desc->lock, flags);
780
781                         return NULL;
782                 }
783
784                 if (action->dev_id == dev_id)
785                         break;
786                 action_ptr = &action->next;
787         }
788
789         /* Found it - now remove it from the list of entries: */
790         *action_ptr = action->next;
791
792         /* Currently used only by UML, might disappear one day: */
793 #ifdef CONFIG_IRQ_RELEASE_METHOD
794         if (desc->chip->release)
795                 desc->chip->release(irq, dev_id);
796 #endif
797
798         /* If this was the last handler, shut down the IRQ line: */
799         if (!desc->action) {
800                 desc->status |= IRQ_DISABLED;
801                 if (desc->chip->shutdown)
802                         desc->chip->shutdown(irq);
803                 else
804                         desc->chip->disable(irq);
805         }
806
807         irqthread = action->thread;
808         action->thread = NULL;
809
810         spin_unlock_irqrestore(&desc->lock, flags);
811
812         unregister_handler_proc(irq, action);
813
814         /* Make sure it's not being used on another CPU: */
815         synchronize_irq(irq);
816
817         if (irqthread) {
818                 if (!test_bit(IRQTF_DIED, &action->thread_flags))
819                         kthread_stop(irqthread);
820                 put_task_struct(irqthread);
821         }
822
823 #ifdef CONFIG_DEBUG_SHIRQ
824         /*
825          * It's a shared IRQ -- the driver ought to be prepared for an IRQ
826          * event to happen even now it's being freed, so let's make sure that
827          * is so by doing an extra call to the handler ....
828          *
829          * ( We do this after actually deregistering it, to make sure that a
830          *   'real' IRQ doesn't run in * parallel with our fake. )
831          */
832         if (action->flags & IRQF_SHARED) {
833                 local_irq_save(flags);
834                 action->handler(irq, dev_id);
835                 local_irq_restore(flags);
836         }
837 #endif
838         return action;
839 }
840
841 /**
842  *      remove_irq - free an interrupt
843  *      @irq: Interrupt line to free
844  *      @act: irqaction for the interrupt
845  *
846  * Used to remove interrupts statically setup by the early boot process.
847  */
848 void remove_irq(unsigned int irq, struct irqaction *act)
849 {
850         __free_irq(irq, act->dev_id);
851 }
852 EXPORT_SYMBOL_GPL(remove_irq);
853
854 /**
855  *      free_irq - free an interrupt allocated with request_irq
856  *      @irq: Interrupt line to free
857  *      @dev_id: Device identity to free
858  *
859  *      Remove an interrupt handler. The handler is removed and if the
860  *      interrupt line is no longer in use by any driver it is disabled.
861  *      On a shared IRQ the caller must ensure the interrupt is disabled
862  *      on the card it drives before calling this function. The function
863  *      does not return until any executing interrupts for this IRQ
864  *      have completed.
865  *
866  *      This function must not be called from interrupt context.
867  */
868 void free_irq(unsigned int irq, void *dev_id)
869 {
870         kfree(__free_irq(irq, dev_id));
871 }
872 EXPORT_SYMBOL(free_irq);
873
874 /**
875  *      request_threaded_irq - allocate an interrupt line
876  *      @irq: Interrupt line to allocate
877  *      @handler: Function to be called when the IRQ occurs.
878  *                Primary handler for threaded interrupts
879  *      @thread_fn: Function called from the irq handler thread
880  *                  If NULL, no irq thread is created
881  *      @irqflags: Interrupt type flags
882  *      @devname: An ascii name for the claiming device
883  *      @dev_id: A cookie passed back to the handler function
884  *
885  *      This call allocates interrupt resources and enables the
886  *      interrupt line and IRQ handling. From the point this
887  *      call is made your handler function may be invoked. Since
888  *      your handler function must clear any interrupt the board
889  *      raises, you must take care both to initialise your hardware
890  *      and to set up the interrupt handler in the right order.
891  *
892  *      If you want to set up a threaded irq handler for your device
893  *      then you need to supply @handler and @thread_fn. @handler ist
894  *      still called in hard interrupt context and has to check
895  *      whether the interrupt originates from the device. If yes it
896  *      needs to disable the interrupt on the device and return
897  *      IRQ_WAKE_THREAD which will wake up the handler thread and run
898  *      @thread_fn. This split handler design is necessary to support
899  *      shared interrupts.
900  *
901  *      Dev_id must be globally unique. Normally the address of the
902  *      device data structure is used as the cookie. Since the handler
903  *      receives this value it makes sense to use it.
904  *
905  *      If your interrupt is shared you must pass a non NULL dev_id
906  *      as this is required when freeing the interrupt.
907  *
908  *      Flags:
909  *
910  *      IRQF_SHARED             Interrupt is shared
911  *      IRQF_DISABLED   Disable local interrupts while processing
912  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
913  *      IRQF_TRIGGER_*          Specify active edge(s) or level
914  *
915  */
916 int request_threaded_irq(unsigned int irq, irq_handler_t handler,
917                          irq_handler_t thread_fn, unsigned long irqflags,
918                          const char *devname, void *dev_id)
919 {
920         struct irqaction *action;
921         struct irq_desc *desc;
922         int retval;
923
924         /*
925          * handle_IRQ_event() always ignores IRQF_DISABLED except for
926          * the _first_ irqaction (sigh).  That can cause oopsing, but
927          * the behavior is classified as "will not fix" so we need to
928          * start nudging drivers away from using that idiom.
929          */
930         if ((irqflags & (IRQF_SHARED|IRQF_DISABLED)) ==
931                                         (IRQF_SHARED|IRQF_DISABLED)) {
932                 pr_warning(
933                   "IRQ %d/%s: IRQF_DISABLED is not guaranteed on shared IRQs\n",
934                         irq, devname);
935         }
936
937 #ifdef CONFIG_LOCKDEP
938         /*
939          * Lockdep wants atomic interrupt handlers:
940          */
941         irqflags |= IRQF_DISABLED;
942 #endif
943         /*
944          * Sanity-check: shared interrupts must pass in a real dev-ID,
945          * otherwise we'll have trouble later trying to figure out
946          * which interrupt is which (messes up the interrupt freeing
947          * logic etc).
948          */
949         if ((irqflags & IRQF_SHARED) && !dev_id)
950                 return -EINVAL;
951
952         desc = irq_to_desc(irq);
953         if (!desc)
954                 return -EINVAL;
955
956         if (desc->status & IRQ_NOREQUEST)
957                 return -EINVAL;
958         if (!handler)
959                 return -EINVAL;
960
961         action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
962         if (!action)
963                 return -ENOMEM;
964
965         action->handler = handler;
966         action->thread_fn = thread_fn;
967         action->flags = irqflags;
968         action->name = devname;
969         action->dev_id = dev_id;
970
971         retval = __setup_irq(irq, desc, action);
972         if (retval)
973                 kfree(action);
974
975 #ifdef CONFIG_DEBUG_SHIRQ
976         if (irqflags & IRQF_SHARED) {
977                 /*
978                  * It's a shared IRQ -- the driver ought to be prepared for it
979                  * to happen immediately, so let's make sure....
980                  * We disable the irq to make sure that a 'real' IRQ doesn't
981                  * run in parallel with our fake.
982                  */
983                 unsigned long flags;
984
985                 disable_irq(irq);
986                 local_irq_save(flags);
987
988                 handler(irq, dev_id);
989
990                 local_irq_restore(flags);
991                 enable_irq(irq);
992         }
993 #endif
994         return retval;
995 }
996 EXPORT_SYMBOL(request_threaded_irq);