include/linux/tqueue.h

/* */
This source file includes following definitions.
queue_task_irq
queue_task_irq_off
queue_task
run_task_queue
   1 /*
   2  * tqueue.h --- task queue handling for Linux.
   3  *
   4  * Mostly based on a proposed bottom-half replacement code written by
   5  * Kai Petzke, wpp@marie.physik.tu-berlin.de.
   6  *
   7  * Modified for use in the Linux kernel by Theodore Ts'o,
   8  * tytso@mit.edu.  Any bugs are my fault, not Kai's.
   9  *
  10  * The original comment follows below.
  11  */
  12 
  13 #ifndef _LINUX_TQUEUE_H
  14 #define _LINUX_TQUEUE_H
  15 
  16 #include <asm/bitops.h>
  17 #include <asm/system.h>
  18 
  19 #ifdef INCLUDE_INLINE_FUNCS
  20 #define _INLINE_ extern
  21 #else
  22 #define _INLINE_ extern __inline__
  23 #endif
  24 
  25 /*
  26  * New proposed "bottom half" handlers:
  27  * (C) 1994 Kai Petzke, wpp@marie.physik.tu-berlin.de
  28  *
  29  * Advantages:
  30  * - Bottom halfs are implemented as a linked list.  You can have as many
  31  *   of them, as you want.
  32  * - No more scanning of a bit field is required upon call of a bottom half.
  33  * - Support for chained bottom half lists.  The run_task_queue() function can be
  34  *   used as a bottom half handler.  This is for example useful for bottom
  35  *   halfs, which want to be delayed until the next clock tick.
  36  *
  37  * Problems:
  38  * - The queue_task_irq() inline function is only atomic with respect to itself.
  39  *   Problems can occur, when queue_task_irq() is called from a normal system
  40  *   call, and an interrupt comes in.  No problems occur, when queue_task_irq()
  41  *   is called from an interrupt or bottom half, and interrupted, as run_task_queue()
  42  *   will not be executed/continued before the last interrupt returns.  If in
  43  *   doubt, use queue_task(), not queue_task_irq().
  44  * - Bottom halfs are called in the reverse order that they were linked into
  45  *   the list.
  46  */
  47 
  48 struct tq_struct {
  49         struct tq_struct *next;         /* linked list of active bh's */
  50         int sync;                       /* must be initialized to zero */
  51         void (*routine)(void *);        /* function to call */
  52         void *data;                     /* argument to function */
  53 };
  54 
  55 typedef struct tq_struct * task_queue;
  56 
  57 #define DECLARE_TASK_QUEUE(q)  task_queue q = &tq_last
  58 
  59 extern struct tq_struct tq_last;
  60 extern task_queue tq_timer, tq_immediate, tq_scheduler;
  61 
  62 #ifdef INCLUDE_INLINE_FUNCS
  63 struct tq_struct tq_last = {
  64         &tq_last, 0, 0, 0
  65 };
  66 #endif
  67 
  68 /*
  69  * To implement your own list of active bottom halfs, use the following
  70  * two definitions:
  71  *
  72  * struct tq_struct *my_bh = &tq_last;
  73  * struct tq_struct run_my_bh = {
  74  *      0, 0, (void *)(void *) run_task_queue, &my_bh
  75  * };
  76  *
  77  * To activate a bottom half on your list, use:
  78  *
  79  *     queue_task(tq_pointer, &my_bh);
  80  *
  81  * To run the bottom halfs on your list put them on the immediate list by:
  82  *
  83  *     queue_task(&run_my_bh, &tq_immediate);
  84  *
  85  * This allows you to do deferred procession.  For example, you could
  86  * have a bottom half list tq_timer, which is marked active by the timer
  87  * interrupt.
  88  */
  89 
  90 /*
  91  * queue_task_irq: put the bottom half handler "bh_pointer" on the list
  92  * "bh_list".  You may call this function only from an interrupt
  93  * handler or a bottom half handler.
  94  */
  95 _INLINE_ void queue_task_irq(struct tq_struct *bh_pointer,
     /*  */
  96                                task_queue *bh_list)
  97 {
  98         if (!set_bit(0,&bh_pointer->sync)) {
  99                 bh_pointer->next = *bh_list;
 100                 *bh_list = bh_pointer;
 101         }
 102 }
 103 
 104 /*
 105  * queue_task_irq_off: put the bottom half handler "bh_pointer" on the list
 106  * "bh_list".  You may call this function only when interrupts are off.
 107  */
 108 _INLINE_ void queue_task_irq_off(struct tq_struct *bh_pointer,
     /*  */
 109                                  task_queue *bh_list)
 110 {
 111         if (!(bh_pointer->sync & 1)) {
 112                 bh_pointer->sync = 1;
 113                 bh_pointer->next = *bh_list;
 114                 *bh_list = bh_pointer;
 115         }
 116 }
 117 
 118 
 119 /*
 120  * queue_task: as queue_task_irq, but can be called from anywhere.
 121  */
 122 _INLINE_ void queue_task(struct tq_struct *bh_pointer,
     /*  */
 123                            task_queue *bh_list)
 124 {
 125         if (!set_bit(0,&bh_pointer->sync)) {
 126                 unsigned long flags;
 127                 save_flags(flags);
 128                 cli();
 129                 bh_pointer->next = *bh_list;
 130                 *bh_list = bh_pointer;
 131                 restore_flags(flags);
 132         }
 133 }
 134 
 135 /*
 136  * Call all "bottom halfs" on a given list.
 137  */
 138 _INLINE_ void run_task_queue(task_queue *list)
     /*  */
 139 {
 140         register struct tq_struct *save_p;
 141         register struct tq_struct *p;
 142         void *arg;
 143         void (*f) (void *);
 144 
 145         while(1) {
 146                 p = xchg_ptr(list,&tq_last);
 147                 if(p == &tq_last)
 148                         break;
 149 
 150                 do {
 151                         arg    = p -> data;
 152                         f      = p -> routine;
 153                         save_p = p -> next;
 154                         p -> sync = 0;
 155                         (*f)(arg);
 156                         p = save_p;
 157                 } while(p != &tq_last);
 158         }
 159 }
 160 
 161 #undef _INLINE_
 162 
 163 #endif /* _LINUX_TQUEUE_H */
/* */
root/include/linux/tqueue.h

INCLUDED FROM

DEFINITIONS
