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

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Asynchronous refcounty things
   4  *
   5  * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
   6  * Copyright 2012 Google, Inc.
   7  */
   8
   9 #include <linux/closure.h>
  10 #include <linux/debugfs.h>
  11 #include <linux/export.h>
  12 #include <linux/seq_file.h>
  13 #include <linux/sched/debug.h>
  14
  15 static inline void closure_put_after_sub(struct closure *cl, int flags)
  16 {
  17         int r = flags & CLOSURE_REMAINING_MASK;
  18
  19         BUG_ON(flags & CLOSURE_GUARD_MASK);
  20         BUG_ON(!r && (flags & ~CLOSURE_DESTRUCTOR));
  21
  22         if (!r) {
  23                 if (cl->fn && !(flags & CLOSURE_DESTRUCTOR)) {
  24                         atomic_set(&cl->remaining,
  25                                    CLOSURE_REMAINING_INITIALIZER);
  26                         closure_queue(cl);
  27                 } else {
  28                         struct closure *parent = cl->parent;
  29                         closure_fn *destructor = cl->fn;
  30
  31                         closure_debug_destroy(cl);
  32
  33                         if (destructor)
  34                                 destructor(cl);
  35
  36                         if (parent)
  37                                 closure_put(parent);
  38                 }
  39         }
  40 }
  41
  42 /* For clearing flags with the same atomic op as a put */
  43 void closure_sub(struct closure *cl, int v)
  44 {
  45         closure_put_after_sub(cl, atomic_sub_return(v, &cl->remaining));
  46 }
  47 EXPORT_SYMBOL(closure_sub);
  48
  49 /*
  50  * closure_put - decrement a closure's refcount
  51  */
  52 void closure_put(struct closure *cl)
  53 {
  54         closure_put_after_sub(cl, atomic_dec_return(&cl->remaining));
  55 }
  56 EXPORT_SYMBOL(closure_put);
  57
  58 /*
  59  * closure_wake_up - wake up all closures on a wait list, without memory barrier
  60  */
  61 void __closure_wake_up(struct closure_waitlist *wait_list)
  62 {
  63         struct llist_node *list;
  64         struct closure *cl, *t;
  65         struct llist_node *reverse = NULL;
  66
  67         list = llist_del_all(&wait_list->list);
  68
  69         /* We first reverse the list to preserve FIFO ordering and fairness */
  70         reverse = llist_reverse_order(list);
  71
  72         /* Then do the wakeups */
  73         llist_for_each_entry_safe(cl, t, reverse, list) {
  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  * @waitlist: will own a ref on @cl, which will be released when
  83  * closure_wake_up() is called on @waitlist.
  84  * @cl: closure pointer.
  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         struct closure_syncer *s = cl->s;
 108         struct task_struct *p;
 109
 110         rcu_read_lock();
 111         p = READ_ONCE(s->task);
 112         s->done = 1;
 113         wake_up_process(p);
 114         rcu_read_unlock();
 115 }
 116
 117 void __sched __closure_sync(struct closure *cl)
 118 {
 119         struct closure_syncer s = { .task = current };
 120
 121         cl->s = &s;
 122         continue_at(cl, closure_sync_fn, NULL);
 123
 124         while (1) {
 125                 set_current_state(TASK_UNINTERRUPTIBLE);
 126                 if (s.done)
 127                         break;
 128                 schedule();
 129         }
 130
 131         __set_current_state(TASK_RUNNING);
 132 }
 133 EXPORT_SYMBOL(__closure_sync);
 134
 135 #ifdef CONFIG_DEBUG_CLOSURES
 136
 137 static LIST_HEAD(closure_list);
 138 static DEFINE_SPINLOCK(closure_list_lock);
 139
 140 void closure_debug_create(struct closure *cl)
 141 {
 142         unsigned long flags;
 143
 144         BUG_ON(cl->magic == CLOSURE_MAGIC_ALIVE);
 145         cl->magic = CLOSURE_MAGIC_ALIVE;
 146
 147         spin_lock_irqsave(&closure_list_lock, flags);
 148         list_add(&cl->all, &closure_list);
 149         spin_unlock_irqrestore(&closure_list_lock, flags);
 150 }
 151 EXPORT_SYMBOL(closure_debug_create);
 152
 153 void closure_debug_destroy(struct closure *cl)
 154 {
 155         unsigned long flags;
 156
 157         BUG_ON(cl->magic != CLOSURE_MAGIC_ALIVE);
 158         cl->magic = CLOSURE_MAGIC_DEAD;
 159
 160         spin_lock_irqsave(&closure_list_lock, flags);
 161         list_del(&cl->all);
 162         spin_unlock_irqrestore(&closure_list_lock, flags);
 163 }
 164 EXPORT_SYMBOL(closure_debug_destroy);
 165
 166 static int debug_show(struct seq_file *f, void *data)
 167 {
 168         struct closure *cl;
 169
 170         spin_lock_irq(&closure_list_lock);
 171
 172         list_for_each_entry(cl, &closure_list, all) {
 173                 int r = atomic_read(&cl->remaining);
 174
 175                 seq_printf(f, "%p: %pS -> %pS p %p r %i ",
 176                            cl, (void *) cl->ip, cl->fn, cl->parent,
 177                            r & CLOSURE_REMAINING_MASK);
 178
 179                 seq_printf(f, "%s%s\n",
 180                            test_bit(WORK_STRUCT_PENDING_BIT,
 181                                     work_data_bits(&cl->work)) ? "Q" : "",
 182                            r & CLOSURE_RUNNING  ? "R" : "");
 183
 184                 if (r & CLOSURE_WAITING)
 185                         seq_printf(f, " W %pS\n",
 186                                    (void *) cl->waiting_on);
 187
 188                 seq_puts(f, "\n");
 189         }
 190
 191         spin_unlock_irq(&closure_list_lock);
 192         return 0;
 193 }
 194
 195 DEFINE_SHOW_ATTRIBUTE(debug);
 196
 197 static int __init closure_debug_init(void)
 198 {
 199         debugfs_create_file("closures", 0400, NULL, NULL, &debug_fops);
 200         return 0;
 201 }
 202 late_initcall(closure_debug_init)
 203
 204 #endif