root/include/linux/interrupt.h

INCLUDED FROM

DEFINITIONS

1. request_irq
2. request_percpu_irq
3. devm_request_irq
4. irq_set_affinity
5. irq_force_affinity
6. irq_set_affinity
7. irq_force_affinity
8. irq_can_set_affinity
9. irq_select_affinity
10. irq_set_affinity_hint
11. irq_set_affinity_notifier
12. irq_create_affinity_masks
13. irq_calc_affinity_vectors
14. disable_irq_nosync_lockdep
15. disable_irq_nosync_lockdep_irqsave
16. disable_irq_lockdep
17. enable_irq_lockdep
18. enable_irq_lockdep_irqrestore
19. enable_irq_wake
20. disable_irq_wake
21. do_softirq_own_stack
22. this_cpu_ksoftirqd
23. tasklet_trylock
24. tasklet_unlock
25. tasklet_unlock_wait
26. tasklet_schedule
27. tasklet_hi_schedule
28. tasklet_disable_nosync
29. tasklet_disable
30. tasklet_enable
31. probe_irq_on
32. probe_irq_off
33. probe_irq_mask
34. init_irq_proc

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /* interrupt.h */
   3 #ifndef _LINUX_INTERRUPT_H
   4 #define _LINUX_INTERRUPT_H
   5 
   6 #include <linux/kernel.h>
   7 #include <linux/bitops.h>
   8 #include <linux/cpumask.h>
   9 #include <linux/irqreturn.h>
  10 #include <linux/irqnr.h>
  11 #include <linux/hardirq.h>
  12 #include <linux/irqflags.h>
  13 #include <linux/hrtimer.h>
  14 #include <linux/kref.h>
  15 #include <linux/workqueue.h>
  16 
  17 #include <linux/atomic.h>
  18 #include <asm/ptrace.h>
  19 #include <asm/irq.h>
  20 #include <asm/sections.h>
  21 
  22 /*
  23  * These correspond to the IORESOURCE_IRQ_* defines in
  24  * linux/ioport.h to select the interrupt line behaviour.  When
  25  * requesting an interrupt without specifying a IRQF_TRIGGER, the
  26  * setting should be assumed to be "as already configured", which
  27  * may be as per machine or firmware initialisation.
  28  */
  29 #define IRQF_TRIGGER_NONE       0x00000000
  30 #define IRQF_TRIGGER_RISING     0x00000001
  31 #define IRQF_TRIGGER_FALLING    0x00000002
  32 #define IRQF_TRIGGER_HIGH       0x00000004
  33 #define IRQF_TRIGGER_LOW        0x00000008
  34 #define IRQF_TRIGGER_MASK       (IRQF_TRIGGER_HIGH | IRQF_TRIGGER_LOW | \
  35                                  IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING)
  36 #define IRQF_TRIGGER_PROBE      0x00000010
  37 
  38 /*
  39  * These flags used only by the kernel as part of the
  40  * irq handling routines.
  41  *
  42  * IRQF_SHARED - allow sharing the irq among several devices
  43  * IRQF_PROBE_SHARED - set by callers when they expect sharing mismatches to occur
  44  * IRQF_TIMER - Flag to mark this interrupt as timer interrupt
  45  * IRQF_PERCPU - Interrupt is per cpu
  46  * IRQF_NOBALANCING - Flag to exclude this interrupt from irq balancing
  47  * IRQF_IRQPOLL - Interrupt is used for polling (only the interrupt that is
  48  *                registered first in a shared interrupt is considered for
  49  *                performance reasons)
  50  * IRQF_ONESHOT - Interrupt is not reenabled after the hardirq handler finished.
  51  *                Used by threaded interrupts which need to keep the
  52  *                irq line disabled until the threaded handler has been run.
  53  * IRQF_NO_SUSPEND - Do not disable this IRQ during suspend.  Does not guarantee
  54  *                   that this interrupt will wake the system from a suspended
  55  *                   state.  See Documentation/power/suspend-and-interrupts.rst
  56  * IRQF_FORCE_RESUME - Force enable it on resume even if IRQF_NO_SUSPEND is set
  57  * IRQF_NO_THREAD - Interrupt cannot be threaded
  58  * IRQF_EARLY_RESUME - Resume IRQ early during syscore instead of at device
  59  *                resume time.
  60  * IRQF_COND_SUSPEND - If the IRQ is shared with a NO_SUSPEND user, execute this
  61  *                interrupt handler after suspending interrupts. For system
  62  *                wakeup devices users need to implement wakeup detection in
  63  *                their interrupt handlers.
  64  */
  65 #define IRQF_SHARED             0x00000080
  66 #define IRQF_PROBE_SHARED       0x00000100
  67 #define __IRQF_TIMER            0x00000200
  68 #define IRQF_PERCPU             0x00000400
  69 #define IRQF_NOBALANCING        0x00000800
  70 #define IRQF_IRQPOLL            0x00001000
  71 #define IRQF_ONESHOT            0x00002000
  72 #define IRQF_NO_SUSPEND         0x00004000
  73 #define IRQF_FORCE_RESUME       0x00008000
  74 #define IRQF_NO_THREAD          0x00010000
  75 #define IRQF_EARLY_RESUME       0x00020000
  76 #define IRQF_COND_SUSPEND       0x00040000
  77 
  78 #define IRQF_TIMER              (__IRQF_TIMER | IRQF_NO_SUSPEND | IRQF_NO_THREAD)
  79 
  80 /*
  81  * These values can be returned by request_any_context_irq() and
  82  * describe the context the interrupt will be run in.
  83  *
  84  * IRQC_IS_HARDIRQ - interrupt runs in hardirq context
  85  * IRQC_IS_NESTED - interrupt runs in a nested threaded context
  86  */
  87 enum {
  88         IRQC_IS_HARDIRQ = 0,
  89         IRQC_IS_NESTED,
  90 };
  91 
  92 typedef irqreturn_t (*irq_handler_t)(int, void *);
  93 
  94 /**
  95  * struct irqaction - per interrupt action descriptor
  96  * @handler:    interrupt handler function
  97  * @name:       name of the device
  98  * @dev_id:     cookie to identify the device
  99  * @percpu_dev_id:      cookie to identify the device
 100  * @next:       pointer to the next irqaction for shared interrupts
 101  * @irq:        interrupt number
 102  * @flags:      flags (see IRQF_* above)
 103  * @thread_fn:  interrupt handler function for threaded interrupts
 104  * @thread:     thread pointer for threaded interrupts
 105  * @secondary:  pointer to secondary irqaction (force threading)
 106  * @thread_flags:       flags related to @thread
 107  * @thread_mask:        bitmask for keeping track of @thread activity
 108  * @dir:        pointer to the proc/irq/NN/name entry
 109  */
 110 struct irqaction {
 111         irq_handler_t           handler;
 112         void                    *dev_id;
 113         void __percpu           *percpu_dev_id;
 114         struct irqaction        *next;
 115         irq_handler_t           thread_fn;
 116         struct task_struct      *thread;
 117         struct irqaction        *secondary;
 118         unsigned int            irq;
 119         unsigned int            flags;
 120         unsigned long           thread_flags;
 121         unsigned long           thread_mask;
 122         const char              *name;
 123         struct proc_dir_entry   *dir;
 124 } ____cacheline_internodealigned_in_smp;
 125 
 126 extern irqreturn_t no_action(int cpl, void *dev_id);
 127 
 128 /*
 129  * If a (PCI) device interrupt is not connected we set dev->irq to
 130  * IRQ_NOTCONNECTED. This causes request_irq() to fail with -ENOTCONN, so we
 131  * can distingiush that case from other error returns.
 132  *
 133  * 0x80000000 is guaranteed to be outside the available range of interrupts
 134  * and easy to distinguish from other possible incorrect values.
 135  */
 136 #define IRQ_NOTCONNECTED        (1U << 31)
 137 
 138 extern int __must_check
 139 request_threaded_irq(unsigned int irq, irq_handler_t handler,
 140                      irq_handler_t thread_fn,
 141                      unsigned long flags, const char *name, void *dev);
 142 
 143 static inline int __must_check
 144 request_irq(unsigned int irq, irq_handler_t handler, unsigned long flags,
 145             const char *name, void *dev)
 146 {
 147         return request_threaded_irq(irq, handler, NULL, flags, name, dev);
 148 }
 149 
 150 extern int __must_check
 151 request_any_context_irq(unsigned int irq, irq_handler_t handler,
 152                         unsigned long flags, const char *name, void *dev_id);
 153 
 154 extern int __must_check
 155 __request_percpu_irq(unsigned int irq, irq_handler_t handler,
 156                      unsigned long flags, const char *devname,
 157                      void __percpu *percpu_dev_id);
 158 
 159 extern int __must_check
 160 request_nmi(unsigned int irq, irq_handler_t handler, unsigned long flags,
 161             const char *name, void *dev);
 162 
 163 static inline int __must_check
 164 request_percpu_irq(unsigned int irq, irq_handler_t handler,
 165                    const char *devname, void __percpu *percpu_dev_id)
 166 {
 167         return __request_percpu_irq(irq, handler, 0,
 168                                     devname, percpu_dev_id);
 169 }
 170 
 171 extern int __must_check
 172 request_percpu_nmi(unsigned int irq, irq_handler_t handler,
 173                    const char *devname, void __percpu *dev);
 174 
 175 extern const void *free_irq(unsigned int, void *);
 176 extern void free_percpu_irq(unsigned int, void __percpu *);
 177 
 178 extern const void *free_nmi(unsigned int irq, void *dev_id);
 179 extern void free_percpu_nmi(unsigned int irq, void __percpu *percpu_dev_id);
 180 
 181 struct device;
 182 
 183 extern int __must_check
 184 devm_request_threaded_irq(struct device *dev, unsigned int irq,
 185                           irq_handler_t handler, irq_handler_t thread_fn,
 186                           unsigned long irqflags, const char *devname,
 187                           void *dev_id);
 188 
 189 static inline int __must_check
 190 devm_request_irq(struct device *dev, unsigned int irq, irq_handler_t handler,
 191                  unsigned long irqflags, const char *devname, void *dev_id)
 192 {
 193         return devm_request_threaded_irq(dev, irq, handler, NULL, irqflags,
 194                                          devname, dev_id);
 195 }
 196 
 197 extern int __must_check
 198 devm_request_any_context_irq(struct device *dev, unsigned int irq,
 199                  irq_handler_t handler, unsigned long irqflags,
 200                  const char *devname, void *dev_id);
 201 
 202 extern void devm_free_irq(struct device *dev, unsigned int irq, void *dev_id);
 203 
 204 /*
 205  * On lockdep we dont want to enable hardirqs in hardirq
 206  * context. Use local_irq_enable_in_hardirq() to annotate
 207  * kernel code that has to do this nevertheless (pretty much
 208  * the only valid case is for old/broken hardware that is
 209  * insanely slow).
 210  *
 211  * NOTE: in theory this might break fragile code that relies
 212  * on hardirq delivery - in practice we dont seem to have such
 213  * places left. So the only effect should be slightly increased
 214  * irqs-off latencies.
 215  */
 216 #ifdef CONFIG_LOCKDEP
 217 # define local_irq_enable_in_hardirq()  do { } while (0)
 218 #else
 219 # define local_irq_enable_in_hardirq()  local_irq_enable()
 220 #endif
 221 
 222 extern void disable_irq_nosync(unsigned int irq);
 223 extern bool disable_hardirq(unsigned int irq);
 224 extern void disable_irq(unsigned int irq);
 225 extern void disable_percpu_irq(unsigned int irq);
 226 extern void enable_irq(unsigned int irq);
 227 extern void enable_percpu_irq(unsigned int irq, unsigned int type);
 228 extern bool irq_percpu_is_enabled(unsigned int irq);
 229 extern void irq_wake_thread(unsigned int irq, void *dev_id);
 230 
 231 extern void disable_nmi_nosync(unsigned int irq);
 232 extern void disable_percpu_nmi(unsigned int irq);
 233 extern void enable_nmi(unsigned int irq);
 234 extern void enable_percpu_nmi(unsigned int irq, unsigned int type);
 235 extern int prepare_percpu_nmi(unsigned int irq);
 236 extern void teardown_percpu_nmi(unsigned int irq);
 237 
 238 /* The following three functions are for the core kernel use only. */
 239 extern void suspend_device_irqs(void);
 240 extern void resume_device_irqs(void);
 241 extern void rearm_wake_irq(unsigned int irq);
 242 
 243 /**
 244  * struct irq_affinity_notify - context for notification of IRQ affinity changes
 245  * @irq:                Interrupt to which notification applies
 246  * @kref:               Reference count, for internal use
 247  * @work:               Work item, for internal use
 248  * @notify:             Function to be called on change.  This will be
 249  *                      called in process context.
 250  * @release:            Function to be called on release.  This will be
 251  *                      called in process context.  Once registered, the
 252  *                      structure must only be freed when this function is
 253  *                      called or later.
 254  */
 255 struct irq_affinity_notify {
 256         unsigned int irq;
 257         struct kref kref;
 258         struct work_struct work;
 259         void (*notify)(struct irq_affinity_notify *, const cpumask_t *mask);
 260         void (*release)(struct kref *ref);
 261 };
 262 
 263 #define IRQ_AFFINITY_MAX_SETS  4
 264 
 265 /**
 266  * struct irq_affinity - Description for automatic irq affinity assignements
 267  * @pre_vectors:        Don't apply affinity to @pre_vectors at beginning of
 268  *                      the MSI(-X) vector space
 269  * @post_vectors:       Don't apply affinity to @post_vectors at end of
 270  *                      the MSI(-X) vector space
 271  * @nr_sets:            The number of interrupt sets for which affinity
 272  *                      spreading is required
 273  * @set_size:           Array holding the size of each interrupt set
 274  * @calc_sets:          Callback for calculating the number and size
 275  *                      of interrupt sets
 276  * @priv:               Private data for usage by @calc_sets, usually a
 277  *                      pointer to driver/device specific data.
 278  */
 279 struct irq_affinity {
 280         unsigned int    pre_vectors;
 281         unsigned int    post_vectors;
 282         unsigned int    nr_sets;
 283         unsigned int    set_size[IRQ_AFFINITY_MAX_SETS];
 284         void            (*calc_sets)(struct irq_affinity *, unsigned int nvecs);
 285         void            *priv;
 286 };
 287 
 288 /**
 289  * struct irq_affinity_desc - Interrupt affinity descriptor
 290  * @mask:       cpumask to hold the affinity assignment
 291  * @is_managed: 1 if the interrupt is managed internally
 292  */
 293 struct irq_affinity_desc {
 294         struct cpumask  mask;
 295         unsigned int    is_managed : 1;
 296 };
 297 
 298 #if defined(CONFIG_SMP)
 299 
 300 extern cpumask_var_t irq_default_affinity;
 301 
 302 /* Internal implementation. Use the helpers below */
 303 extern int __irq_set_affinity(unsigned int irq, const struct cpumask *cpumask,
 304                               bool force);
 305 
 306 /**
 307  * irq_set_affinity - Set the irq affinity of a given irq
 308  * @irq:        Interrupt to set affinity
 309  * @cpumask:    cpumask
 310  *
 311  * Fails if cpumask does not contain an online CPU
 312  */
 313 static inline int
 314 irq_set_affinity(unsigned int irq, const struct cpumask *cpumask)
 315 {
 316         return __irq_set_affinity(irq, cpumask, false);
 317 }
 318 
 319 /**
 320  * irq_force_affinity - Force the irq affinity of a given irq
 321  * @irq:        Interrupt to set affinity
 322  * @cpumask:    cpumask
 323  *
 324  * Same as irq_set_affinity, but without checking the mask against
 325  * online cpus.
 326  *
 327  * Solely for low level cpu hotplug code, where we need to make per
 328  * cpu interrupts affine before the cpu becomes online.
 329  */
 330 static inline int
 331 irq_force_affinity(unsigned int irq, const struct cpumask *cpumask)
 332 {
 333         return __irq_set_affinity(irq, cpumask, true);
 334 }
 335 
 336 extern int irq_can_set_affinity(unsigned int irq);
 337 extern int irq_select_affinity(unsigned int irq);
 338 
 339 extern int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m);
 340 
 341 extern int
 342 irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify);
 343 
 344 struct irq_affinity_desc *
 345 irq_create_affinity_masks(unsigned int nvec, struct irq_affinity *affd);
 346 
 347 unsigned int irq_calc_affinity_vectors(unsigned int minvec, unsigned int maxvec,
 348                                        const struct irq_affinity *affd);
 349 
 350 #else /* CONFIG_SMP */
 351 
 352 static inline int irq_set_affinity(unsigned int irq, const struct cpumask *m)
 353 {
 354         return -EINVAL;
 355 }
 356 
 357 static inline int irq_force_affinity(unsigned int irq, const struct cpumask *cpumask)
 358 {
 359         return 0;
 360 }
 361 
 362 static inline int irq_can_set_affinity(unsigned int irq)
 363 {
 364         return 0;
 365 }
 366 
 367 static inline int irq_select_affinity(unsigned int irq)  { return 0; }
 368 
 369 static inline int irq_set_affinity_hint(unsigned int irq,
 370                                         const struct cpumask *m)
 371 {
 372         return -EINVAL;
 373 }
 374 
 375 static inline int
 376 irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify)
 377 {
 378         return 0;
 379 }
 380 
 381 static inline struct irq_affinity_desc *
 382 irq_create_affinity_masks(unsigned int nvec, struct irq_affinity *affd)
 383 {
 384         return NULL;
 385 }
 386 
 387 static inline unsigned int
 388 irq_calc_affinity_vectors(unsigned int minvec, unsigned int maxvec,
 389                           const struct irq_affinity *affd)
 390 {
 391         return maxvec;
 392 }
 393 
 394 #endif /* CONFIG_SMP */
 395 
 396 /*
 397  * Special lockdep variants of irq disabling/enabling.
 398  * These should be used for locking constructs that
 399  * know that a particular irq context which is disabled,
 400  * and which is the only irq-context user of a lock,
 401  * that it's safe to take the lock in the irq-disabled
 402  * section without disabling hardirqs.
 403  *
 404  * On !CONFIG_LOCKDEP they are equivalent to the normal
 405  * irq disable/enable methods.
 406  */
 407 static inline void disable_irq_nosync_lockdep(unsigned int irq)
 408 {
 409         disable_irq_nosync(irq);
 410 #ifdef CONFIG_LOCKDEP
 411         local_irq_disable();
 412 #endif
 413 }
 414 
 415 static inline void disable_irq_nosync_lockdep_irqsave(unsigned int irq, unsigned long *flags)
 416 {
 417         disable_irq_nosync(irq);
 418 #ifdef CONFIG_LOCKDEP
 419         local_irq_save(*flags);
 420 #endif
 421 }
 422 
 423 static inline void disable_irq_lockdep(unsigned int irq)
 424 {
 425         disable_irq(irq);
 426 #ifdef CONFIG_LOCKDEP
 427         local_irq_disable();
 428 #endif
 429 }
 430 
 431 static inline void enable_irq_lockdep(unsigned int irq)
 432 {
 433 #ifdef CONFIG_LOCKDEP
 434         local_irq_enable();
 435 #endif
 436         enable_irq(irq);
 437 }
 438 
 439 static inline void enable_irq_lockdep_irqrestore(unsigned int irq, unsigned long *flags)
 440 {
 441 #ifdef CONFIG_LOCKDEP
 442         local_irq_restore(*flags);
 443 #endif
 444         enable_irq(irq);
 445 }
 446 
 447 /* IRQ wakeup (PM) control: */
 448 extern int irq_set_irq_wake(unsigned int irq, unsigned int on);
 449 
 450 static inline int enable_irq_wake(unsigned int irq)
 451 {
 452         return irq_set_irq_wake(irq, 1);
 453 }
 454 
 455 static inline int disable_irq_wake(unsigned int irq)
 456 {
 457         return irq_set_irq_wake(irq, 0);
 458 }
 459 
 460 /*
 461  * irq_get_irqchip_state/irq_set_irqchip_state specific flags
 462  */
 463 enum irqchip_irq_state {
 464         IRQCHIP_STATE_PENDING,          /* Is interrupt pending? */
 465         IRQCHIP_STATE_ACTIVE,           /* Is interrupt in progress? */
 466         IRQCHIP_STATE_MASKED,           /* Is interrupt masked? */
 467         IRQCHIP_STATE_LINE_LEVEL,       /* Is IRQ line high? */
 468 };
 469 
 470 extern int irq_get_irqchip_state(unsigned int irq, enum irqchip_irq_state which,
 471                                  bool *state);
 472 extern int irq_set_irqchip_state(unsigned int irq, enum irqchip_irq_state which,
 473                                  bool state);
 474 
 475 #ifdef CONFIG_IRQ_FORCED_THREADING
 476 # ifdef CONFIG_PREEMPT_RT
 477 #  define force_irqthreads      (true)
 478 # else
 479 extern bool force_irqthreads;
 480 # endif
 481 #else
 482 #define force_irqthreads        (0)
 483 #endif
 484 
 485 #ifndef local_softirq_pending
 486 
 487 #ifndef local_softirq_pending_ref
 488 #define local_softirq_pending_ref irq_stat.__softirq_pending
 489 #endif
 490 
 491 #define local_softirq_pending() (__this_cpu_read(local_softirq_pending_ref))
 492 #define set_softirq_pending(x)  (__this_cpu_write(local_softirq_pending_ref, (x)))
 493 #define or_softirq_pending(x)   (__this_cpu_or(local_softirq_pending_ref, (x)))
 494 
 495 #endif /* local_softirq_pending */
 496 
 497 /* Some architectures might implement lazy enabling/disabling of
 498  * interrupts. In some cases, such as stop_machine, we might want
 499  * to ensure that after a local_irq_disable(), interrupts have
 500  * really been disabled in hardware. Such architectures need to
 501  * implement the following hook.
 502  */
 503 #ifndef hard_irq_disable
 504 #define hard_irq_disable()      do { } while(0)
 505 #endif
 506 
 507 /* PLEASE, avoid to allocate new softirqs, if you need not _really_ high
 508    frequency threaded job scheduling. For almost all the purposes
 509    tasklets are more than enough. F.e. all serial device BHs et
 510    al. should be converted to tasklets, not to softirqs.
 511  */
 512 
 513 enum
 514 {
 515         HI_SOFTIRQ=0,
 516         TIMER_SOFTIRQ,
 517         NET_TX_SOFTIRQ,
 518         NET_RX_SOFTIRQ,
 519         BLOCK_SOFTIRQ,
 520         IRQ_POLL_SOFTIRQ,
 521         TASKLET_SOFTIRQ,
 522         SCHED_SOFTIRQ,
 523         HRTIMER_SOFTIRQ, /* Unused, but kept as tools rely on the
 524                             numbering. Sigh! */
 525         RCU_SOFTIRQ,    /* Preferable RCU should always be the last softirq */
 526 
 527         NR_SOFTIRQS
 528 };
 529 
 530 #define SOFTIRQ_STOP_IDLE_MASK (~(1 << RCU_SOFTIRQ))
 531 
 532 /* map softirq index to softirq name. update 'softirq_to_name' in
 533  * kernel/softirq.c when adding a new softirq.
 534  */
 535 extern const char * const softirq_to_name[NR_SOFTIRQS];
 536 
 537 /* softirq mask and active fields moved to irq_cpustat_t in
 538  * asm/hardirq.h to get better cache usage.  KAO
 539  */
 540 
 541 struct softirq_action
 542 {
 543         void    (*action)(struct softirq_action *);
 544 };
 545 
 546 asmlinkage void do_softirq(void);
 547 asmlinkage void __do_softirq(void);
 548 
 549 #ifdef __ARCH_HAS_DO_SOFTIRQ
 550 void do_softirq_own_stack(void);
 551 #else
 552 static inline void do_softirq_own_stack(void)
 553 {
 554         __do_softirq();
 555 }
 556 #endif
 557 
 558 extern void open_softirq(int nr, void (*action)(struct softirq_action *));
 559 extern void softirq_init(void);
 560 extern void __raise_softirq_irqoff(unsigned int nr);
 561 
 562 extern void raise_softirq_irqoff(unsigned int nr);
 563 extern void raise_softirq(unsigned int nr);
 564 
 565 DECLARE_PER_CPU(struct task_struct *, ksoftirqd);
 566 
 567 static inline struct task_struct *this_cpu_ksoftirqd(void)
 568 {
 569         return this_cpu_read(ksoftirqd);
 570 }
 571 
 572 /* Tasklets --- multithreaded analogue of BHs.
 573 
 574    Main feature differing them of generic softirqs: tasklet
 575    is running only on one CPU simultaneously.
 576 
 577    Main feature differing them of BHs: different tasklets
 578    may be run simultaneously on different CPUs.
 579 
 580    Properties:
 581    * If tasklet_schedule() is called, then tasklet is guaranteed
 582      to be executed on some cpu at least once after this.
 583    * If the tasklet is already scheduled, but its execution is still not
 584      started, it will be executed only once.
 585    * If this tasklet is already running on another CPU (or schedule is called
 586      from tasklet itself), it is rescheduled for later.
 587    * Tasklet is strictly serialized wrt itself, but not
 588      wrt another tasklets. If client needs some intertask synchronization,
 589      he makes it with spinlocks.
 590  */
 591 
 592 struct tasklet_struct
 593 {
 594         struct tasklet_struct *next;
 595         unsigned long state;
 596         atomic_t count;
 597         void (*func)(unsigned long);
 598         unsigned long data;
 599 };
 600 
 601 #define DECLARE_TASKLET(name, func, data) \
 602 struct tasklet_struct name = { NULL, 0, ATOMIC_INIT(0), func, data }
 603 
 604 #define DECLARE_TASKLET_DISABLED(name, func, data) \
 605 struct tasklet_struct name = { NULL, 0, ATOMIC_INIT(1), func, data }
 606 
 607 
 608 enum
 609 {
 610         TASKLET_STATE_SCHED,    /* Tasklet is scheduled for execution */
 611         TASKLET_STATE_RUN       /* Tasklet is running (SMP only) */
 612 };
 613 
 614 #ifdef CONFIG_SMP
 615 static inline int tasklet_trylock(struct tasklet_struct *t)
 616 {
 617         return !test_and_set_bit(TASKLET_STATE_RUN, &(t)->state);
 618 }
 619 
 620 static inline void tasklet_unlock(struct tasklet_struct *t)
 621 {
 622         smp_mb__before_atomic();
 623         clear_bit(TASKLET_STATE_RUN, &(t)->state);
 624 }
 625 
 626 static inline void tasklet_unlock_wait(struct tasklet_struct *t)
 627 {
 628         while (test_bit(TASKLET_STATE_RUN, &(t)->state)) { barrier(); }
 629 }
 630 #else
 631 #define tasklet_trylock(t) 1
 632 #define tasklet_unlock_wait(t) do { } while (0)
 633 #define tasklet_unlock(t) do { } while (0)
 634 #endif
 635 
 636 extern void __tasklet_schedule(struct tasklet_struct *t);
 637 
 638 static inline void tasklet_schedule(struct tasklet_struct *t)
 639 {
 640         if (!test_and_set_bit(TASKLET_STATE_SCHED, &t->state))
 641                 __tasklet_schedule(t);
 642 }
 643 
 644 extern void __tasklet_hi_schedule(struct tasklet_struct *t);
 645 
 646 static inline void tasklet_hi_schedule(struct tasklet_struct *t)
 647 {
 648         if (!test_and_set_bit(TASKLET_STATE_SCHED, &t->state))
 649                 __tasklet_hi_schedule(t);
 650 }
 651 
 652 static inline void tasklet_disable_nosync(struct tasklet_struct *t)
 653 {
 654         atomic_inc(&t->count);
 655         smp_mb__after_atomic();
 656 }
 657 
 658 static inline void tasklet_disable(struct tasklet_struct *t)
 659 {
 660         tasklet_disable_nosync(t);
 661         tasklet_unlock_wait(t);
 662         smp_mb();
 663 }
 664 
 665 static inline void tasklet_enable(struct tasklet_struct *t)
 666 {
 667         smp_mb__before_atomic();
 668         atomic_dec(&t->count);
 669 }
 670 
 671 extern void tasklet_kill(struct tasklet_struct *t);
 672 extern void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu);
 673 extern void tasklet_init(struct tasklet_struct *t,
 674                          void (*func)(unsigned long), unsigned long data);
 675 
 676 /*
 677  * Autoprobing for irqs:
 678  *
 679  * probe_irq_on() and probe_irq_off() provide robust primitives
 680  * for accurate IRQ probing during kernel initialization.  They are
 681  * reasonably simple to use, are not "fooled" by spurious interrupts,
 682  * and, unlike other attempts at IRQ probing, they do not get hung on
 683  * stuck interrupts (such as unused PS2 mouse interfaces on ASUS boards).
 684  *
 685  * For reasonably foolproof probing, use them as follows:
 686  *
 687  * 1. clear and/or mask the device's internal interrupt.
 688  * 2. sti();
 689  * 3. irqs = probe_irq_on();      // "take over" all unassigned idle IRQs
 690  * 4. enable the device and cause it to trigger an interrupt.
 691  * 5. wait for the device to interrupt, using non-intrusive polling or a delay.
 692  * 6. irq = probe_irq_off(irqs);  // get IRQ number, 0=none, negative=multiple
 693  * 7. service the device to clear its pending interrupt.
 694  * 8. loop again if paranoia is required.
 695  *
 696  * probe_irq_on() returns a mask of allocated irq's.
 697  *
 698  * probe_irq_off() takes the mask as a parameter,
 699  * and returns the irq number which occurred,
 700  * or zero if none occurred, or a negative irq number
 701  * if more than one irq occurred.
 702  */
 703 
 704 #if !defined(CONFIG_GENERIC_IRQ_PROBE) 
 705 static inline unsigned long probe_irq_on(void)
 706 {
 707         return 0;
 708 }
 709 static inline int probe_irq_off(unsigned long val)
 710 {
 711         return 0;
 712 }
 713 static inline unsigned int probe_irq_mask(unsigned long val)
 714 {
 715         return 0;
 716 }
 717 #else
 718 extern unsigned long probe_irq_on(void);        /* returns 0 on failure */
 719 extern int probe_irq_off(unsigned long);        /* returns 0 or negative on failure */
 720 extern unsigned int probe_irq_mask(unsigned long);      /* returns mask of ISA interrupts */
 721 #endif
 722 
 723 #ifdef CONFIG_PROC_FS
 724 /* Initialize /proc/irq/ */
 725 extern void init_irq_proc(void);
 726 #else
 727 static inline void init_irq_proc(void)
 728 {
 729 }
 730 #endif
 731 
 732 #ifdef CONFIG_IRQ_TIMINGS
 733 void irq_timings_enable(void);
 734 void irq_timings_disable(void);
 735 u64 irq_timings_next_event(u64 now);
 736 #endif
 737 
 738 struct seq_file;
 739 int show_interrupts(struct seq_file *p, void *v);
 740 int arch_show_interrupts(struct seq_file *p, int prec);
 741 
 742 extern int early_irq_init(void);
 743 extern int arch_probe_nr_irqs(void);
 744 extern int arch_early_irq_init(void);
 745 
 746 /*
 747  * We want to know which function is an entrypoint of a hardirq or a softirq.
 748  */
 749 #define __irq_entry              __attribute__((__section__(".irqentry.text")))
 750 #define __softirq_entry  \
 751         __attribute__((__section__(".softirqentry.text")))
 752 
 753 #endif