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/rcupdate.h>
  13 #include <linux/seq_file.h>
  14 #include <linux/sched/debug.h>
  15
  16 static inline void closure_put_after_sub(struct closure *cl, int flags)
  17 {
  18         int r = flags & CLOSURE_REMAINING_MASK;
  19
  20         if ((flags & CLOSURE_GUARD_MASK) ||
  21             (!r && (flags & ~CLOSURE_DESTRUCTOR)))
  22                 panic("closure_put_after_sub: bogus flags %x remaining %i", flags, r);
  23
  24         if (!r) {
  25                 if (cl->fn && !(flags & CLOSURE_DESTRUCTOR)) {
  26                         atomic_set(&cl->remaining,
  27                                    CLOSURE_REMAINING_INITIALIZER);
  28                         closure_queue(cl);
  29                 } else {
  30                         struct closure *parent = cl->parent;
  31                         closure_fn *destructor = cl->fn;
  32
  33                         closure_debug_destroy(cl);
  34
  35                         if (destructor)
  36                                 destructor(cl);
  37
  38                         if (parent)
  39                                 closure_put(parent);
  40                 }
  41         }
  42 }
  43
  44 /* For clearing flags with the same atomic op as a put */
  45 void closure_sub(struct closure *cl, int v)
  46 {
  47         closure_put_after_sub(cl, atomic_sub_return(v, &cl->remaining));
  48 }
  49 EXPORT_SYMBOL(closure_sub);
  50
  51 /*
  52  * closure_put - decrement a closure's refcount
  53  */
  54 void closure_put(struct closure *cl)
  55 {
  56         closure_put_after_sub(cl, atomic_dec_return(&cl->remaining));
  57 }
  58 EXPORT_SYMBOL(closure_put);
  59
  60 /*
  61  * closure_wake_up - wake up all closures on a wait list, without memory barrier
  62  */
  63 void __closure_wake_up(struct closure_waitlist *wait_list)
  64 {
  65         struct llist_node *list;
  66         struct closure *cl, *t;
  67         struct llist_node *reverse = NULL;
  68
  69         list = llist_del_all(&wait_list->list);
  70
  71         /* We first reverse the list to preserve FIFO ordering and fairness */
  72         reverse = llist_reverse_order(list);
  73
  74         /* Then do the wakeups */
  75         llist_for_each_entry_safe(cl, t, reverse, list) {
  76                 closure_set_waiting(cl, 0);
  77                 closure_sub(cl, CLOSURE_WAITING + 1);
  78         }
  79 }
  80 EXPORT_SYMBOL(__closure_wake_up);
  81
  82 /**
  83  * closure_wait - add a closure to a waitlist
  84  * @waitlist: will own a ref on @cl, which will be released when
  85  * closure_wake_up() is called on @waitlist.
  86  * @cl: closure pointer.
  87  *
  88  */
  89 bool closure_wait(struct closure_waitlist *waitlist, struct closure *cl)
  90 {
  91         if (atomic_read(&cl->remaining) & CLOSURE_WAITING)
  92                 return false;
  93
  94         closure_set_waiting(cl, _RET_IP_);
  95         atomic_add(CLOSURE_WAITING + 1, &cl->remaining);
  96         llist_add(&cl->list, &waitlist->list);
  97
  98         return true;
  99 }
 100 EXPORT_SYMBOL(closure_wait);
 101
 102 struct closure_syncer {
 103         struct task_struct      *task;
 104         int                     done;
 105 };
 106
 107 static void closure_sync_fn(struct closure *cl)
 108 {
 109         struct closure_syncer *s = cl->s;
 110         struct task_struct *p;
 111
 112         rcu_read_lock();
 113         p = READ_ONCE(s->task);
 114         s->done = 1;
 115         wake_up_process(p);
 116         rcu_read_unlock();
 117 }
 118
 119 void __sched __closure_sync(struct closure *cl)
 120 {
 121         struct closure_syncer s = { .task = current };
 122
 123         cl->s = &s;
 124         continue_at(cl, closure_sync_fn, NULL);
 125
 126         while (1) {
 127                 set_current_state(TASK_UNINTERRUPTIBLE);
 128                 if (s.done)
 129                         break;
 130                 schedule();
 131         }
 132
 133         __set_current_state(TASK_RUNNING);
 134 }
 135 EXPORT_SYMBOL(__closure_sync);
 136
 137 #ifdef CONFIG_DEBUG_CLOSURES
 138
 139 static LIST_HEAD(closure_list);
 140 static DEFINE_SPINLOCK(closure_list_lock);
 141
 142 void closure_debug_create(struct closure *cl)
 143 {
 144         unsigned long flags;
 145
 146         BUG_ON(cl->magic == CLOSURE_MAGIC_ALIVE);
 147         cl->magic = CLOSURE_MAGIC_ALIVE;
 148
 149         spin_lock_irqsave(&closure_list_lock, flags);
 150         list_add(&cl->all, &closure_list);
 151         spin_unlock_irqrestore(&closure_list_lock, flags);
 152 }
 153 EXPORT_SYMBOL(closure_debug_create);
 154
 155 void closure_debug_destroy(struct closure *cl)
 156 {
 157         unsigned long flags;
 158
 159         BUG_ON(cl->magic != CLOSURE_MAGIC_ALIVE);
 160         cl->magic = CLOSURE_MAGIC_DEAD;
 161
 162         spin_lock_irqsave(&closure_list_lock, flags);
 163         list_del(&cl->all);
 164         spin_unlock_irqrestore(&closure_list_lock, flags);
 165 }
 166 EXPORT_SYMBOL(closure_debug_destroy);
 167
 168 static int debug_show(struct seq_file *f, void *data)
 169 {
 170         struct closure *cl;
 171
 172         spin_lock_irq(&closure_list_lock);
 173
 174         list_for_each_entry(cl, &closure_list, all) {
 175                 int r = atomic_read(&cl->remaining);
 176
 177                 seq_printf(f, "%p: %pS -> %pS p %p r %i ",
 178                            cl, (void *) cl->ip, cl->fn, cl->parent,
 179                            r & CLOSURE_REMAINING_MASK);
 180
 181                 seq_printf(f, "%s%s\n",
 182                            test_bit(WORK_STRUCT_PENDING_BIT,
 183                                     work_data_bits(&cl->work)) ? "Q" : "",
 184                            r & CLOSURE_RUNNING  ? "R" : "");
 185
 186                 if (r & CLOSURE_WAITING)
 187                         seq_printf(f, " W %pS\n",
 188                                    (void *) cl->waiting_on);
 189
 190                 seq_puts(f, "\n");
 191         }
 192
 193         spin_unlock_irq(&closure_list_lock);
 194         return 0;
 195 }
 196
 197 DEFINE_SHOW_ATTRIBUTE(debug);
 198
 199 static int __init closure_debug_init(void)
 200 {
 201         debugfs_create_file("closures", 0400, NULL, NULL, &debug_fops);
 202         return 0;
 203 }
 204 late_initcall(closure_debug_init)
 205
 206 #endif