git.sesse.net Git - bcachefs-tools-debian/blob - libbcache/closure.c

   1 /*
   2  * Asynchronous refcounty things
   3  *
   4  * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
   5  * Copyright 2012 Google, Inc.
   6  */
   7
   8 #include <linux/debugfs.h>
   9 #include <linux/module.h>
  10 #include <linux/seq_file.h>
  11
  12 #include "closure.h"
  13
  14 static inline void closure_put_after_sub(struct closure *cl, int flags)
  15 {
  16         int r = flags & CLOSURE_REMAINING_MASK;
  17
  18         BUG_ON(flags & CLOSURE_GUARD_MASK);
  19         BUG_ON(!r && (flags & ~CLOSURE_DESTRUCTOR));
  20
  21         if (!r) {
  22                 if (cl->fn && !(flags & CLOSURE_DESTRUCTOR)) {
  23                         atomic_set(&cl->remaining,
  24                                    CLOSURE_REMAINING_INITIALIZER);
  25                         closure_queue(cl);
  26                 } else {
  27                         struct closure *parent = cl->parent;
  28                         closure_fn *destructor = cl->fn;
  29
  30                         closure_debug_destroy(cl);
  31
  32                         if (destructor)
  33                                 destructor(cl);
  34
  35                         if (parent)
  36                                 closure_put(parent);
  37                 }
  38         }
  39 }
  40
  41 /* For clearing flags with the same atomic op as a put */
  42 void closure_sub(struct closure *cl, int v)
  43 {
  44         closure_put_after_sub(cl, atomic_sub_return(v, &cl->remaining));
  45 }
  46 EXPORT_SYMBOL(closure_sub);
  47
  48 /**
  49  * closure_put - decrement a closure's refcount
  50  */
  51 void closure_put(struct closure *cl)
  52 {
  53         closure_put_after_sub(cl, atomic_dec_return(&cl->remaining));
  54 }
  55 EXPORT_SYMBOL(closure_put);
  56
  57 /**
  58  * closure_wake_up - wake up all closures on a wait list, without memory barrier
  59  */
  60 void __closure_wake_up(struct closure_waitlist *wait_list)
  61 {
  62         struct llist_node *list, *next;
  63         struct closure *cl;
  64
  65         /*
  66          * Grab entire list, reverse order to preserve FIFO ordering, and wake
  67          * everything up
  68          */
  69         for (list = llist_reverse_order(llist_del_all(&wait_list->list));
  70              list;
  71              list = next) {
  72                 next = llist_next(list);
  73                 cl = container_of(list, struct closure, list);
  74
  75                 closure_set_waiting(cl, 0);
  76                 closure_sub(cl, CLOSURE_WAITING + 1);
  77         }
  78 }
  79 EXPORT_SYMBOL(__closure_wake_up);
  80
  81 /**
  82  * closure_wait - add a closure to a waitlist
  83  *
  84  * @waitlist will own a ref on @cl, which will be released when
  85  * closure_wake_up() is called on @waitlist.
  86  *
  87  */
  88 bool closure_wait(struct closure_waitlist *waitlist, struct closure *cl)
  89 {
  90         if (atomic_read(&cl->remaining) & CLOSURE_WAITING)
  91                 return false;
  92
  93         closure_set_waiting(cl, _RET_IP_);
  94         atomic_add(CLOSURE_WAITING + 1, &cl->remaining);
  95         llist_add(&cl->list, &waitlist->list);
  96
  97         return true;
  98 }
  99 EXPORT_SYMBOL(closure_wait);
 100
 101 struct closure_syncer {
 102         struct task_struct      *task;
 103         int                     done;
 104 };
 105
 106 static void closure_sync_fn(struct closure *cl)
 107 {
 108         cl->s->done = 1;
 109         wake_up_process(cl->s->task);
 110 }
 111
 112 void __sched __closure_sync(struct closure *cl)
 113 {
 114         struct closure_syncer s = { .task = current };
 115
 116         cl->s = &s;
 117         continue_at_noreturn(cl, closure_sync_fn, NULL);
 118
 119         while (1) {
 120                 __set_current_state(TASK_UNINTERRUPTIBLE);
 121                 smp_mb();
 122                 if (s.done)
 123                         break;
 124                 schedule();
 125         }
 126
 127         __set_current_state(TASK_RUNNING);
 128 }
 129 EXPORT_SYMBOL(__closure_sync);
 130
 131 #ifdef CONFIG_BCACHE_CLOSURES_DEBUG
 132
 133 static LIST_HEAD(closure_list);
 134 static DEFINE_SPINLOCK(closure_list_lock);
 135
 136 void closure_debug_create(struct closure *cl)
 137 {
 138         unsigned long flags;
 139
 140         BUG_ON(cl->magic == CLOSURE_MAGIC_ALIVE);
 141         cl->magic = CLOSURE_MAGIC_ALIVE;
 142
 143         spin_lock_irqsave(&closure_list_lock, flags);
 144         list_add(&cl->all, &closure_list);
 145         spin_unlock_irqrestore(&closure_list_lock, flags);
 146 }
 147 EXPORT_SYMBOL(closure_debug_create);
 148
 149 void closure_debug_destroy(struct closure *cl)
 150 {
 151         unsigned long flags;
 152
 153         BUG_ON(cl->magic != CLOSURE_MAGIC_ALIVE);
 154         cl->magic = CLOSURE_MAGIC_DEAD;
 155
 156         spin_lock_irqsave(&closure_list_lock, flags);
 157         list_del(&cl->all);
 158         spin_unlock_irqrestore(&closure_list_lock, flags);
 159 }
 160 EXPORT_SYMBOL(closure_debug_destroy);
 161
 162 static struct dentry *debug;
 163
 164 static int debug_seq_show(struct seq_file *f, void *data)
 165 {
 166         struct closure *cl;
 167
 168         spin_lock_irq(&closure_list_lock);
 169
 170         list_for_each_entry(cl, &closure_list, all) {
 171                 int r = atomic_read(&cl->remaining);
 172
 173                 seq_printf(f, "%p: %pF -> %pf p %p r %i ",
 174                            cl, (void *) cl->ip, cl->fn, cl->parent,
 175                            r & CLOSURE_REMAINING_MASK);
 176
 177                 seq_printf(f, "%s%s\n",
 178                            test_bit(WORK_STRUCT_PENDING_BIT,
 179                                     work_data_bits(&cl->work)) ? "Q" : "",
 180                            r & CLOSURE_RUNNING  ? "R" : "");
 181
 182                 if (r & CLOSURE_WAITING)
 183                         seq_printf(f, " W %pF\n",
 184                                    (void *) cl->waiting_on);
 185
 186                 seq_puts(f, "\n");
 187         }
 188
 189         spin_unlock_irq(&closure_list_lock);
 190         return 0;
 191 }
 192
 193 static int debug_seq_open(struct inode *inode, struct file *file)
 194 {
 195         return single_open(file, debug_seq_show, NULL);
 196 }
 197
 198 static const struct file_operations debug_ops = {
 199         .owner          = THIS_MODULE,
 200         .open           = debug_seq_open,
 201         .read           = seq_read,
 202         .release        = single_release
 203 };
 204
 205 void __init closure_debug_init(void)
 206 {
 207         debug = debugfs_create_file("closures", 0400, NULL, NULL, &debug_ops);
 208 }
 209
 210 #endif