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