drivers/md/bcache/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 #include <linux/sched/debug.h>
  12
  13 #include "closure.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  *
  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(cl, closure_sync_fn, NULL);
 117
 118         while (1) {
 119                 set_current_state(TASK_UNINTERRUPTIBLE);
 120                 if (s.done)
 121                         break;
 122                 schedule();
 123         }
 124
 125         __set_current_state(TASK_RUNNING);
 126 }
 127 EXPORT_SYMBOL(__closure_sync);
 128
 129 #ifdef CONFIG_BCACHE_CLOSURES_DEBUG
 130
 131 static LIST_HEAD(closure_list);
 132 static DEFINE_SPINLOCK(closure_list_lock);
 133
 134 void closure_debug_create(struct closure *cl)
 135 {
 136         unsigned long flags;
 137
 138         BUG_ON(cl->magic == CLOSURE_MAGIC_ALIVE);
 139         cl->magic = CLOSURE_MAGIC_ALIVE;
 140
 141         spin_lock_irqsave(&closure_list_lock, flags);
 142         list_add(&cl->all, &closure_list);
 143         spin_unlock_irqrestore(&closure_list_lock, flags);
 144 }
 145 EXPORT_SYMBOL(closure_debug_create);
 146
 147 void closure_debug_destroy(struct closure *cl)
 148 {
 149         unsigned long flags;
 150
 151         BUG_ON(cl->magic != CLOSURE_MAGIC_ALIVE);
 152         cl->magic = CLOSURE_MAGIC_DEAD;
 153
 154         spin_lock_irqsave(&closure_list_lock, flags);
 155         list_del(&cl->all);
 156         spin_unlock_irqrestore(&closure_list_lock, flags);
 157 }
 158 EXPORT_SYMBOL(closure_debug_destroy);
 159
 160 static struct dentry *debug;
 161
 162 static int debug_seq_show(struct seq_file *f, void *data)
 163 {
 164         struct closure *cl;
 165         spin_lock_irq(&closure_list_lock);
 166
 167         list_for_each_entry(cl, &closure_list, all) {
 168                 int r = atomic_read(&cl->remaining);
 169
 170                 seq_printf(f, "%p: %pF -> %pf p %p r %i ",
 171                            cl, (void *) cl->ip, cl->fn, cl->parent,
 172                            r & CLOSURE_REMAINING_MASK);
 173
 174                 seq_printf(f, "%s%s\n",
 175                            test_bit(WORK_STRUCT_PENDING_BIT,
 176                                     work_data_bits(&cl->work)) ? "Q" : "",
 177                            r & CLOSURE_RUNNING  ? "R" : "");
 178
 179                 if (r & CLOSURE_WAITING)
 180                         seq_printf(f, " W %pF\n",
 181                                    (void *) cl->waiting_on);
 182
 183                 seq_printf(f, "\n");
 184         }
 185
 186         spin_unlock_irq(&closure_list_lock);
 187         return 0;
 188 }
 189
 190 static int debug_seq_open(struct inode *inode, struct file *file)
 191 {
 192         return single_open(file, debug_seq_show, NULL);
 193 }
 194
 195 static const struct file_operations debug_ops = {
 196         .owner          = THIS_MODULE,
 197         .open           = debug_seq_open,
 198         .read           = seq_read,
 199         .release        = single_release
 200 };
 201
 202 void __init closure_debug_init(void)
 203 {
 204         debug = debugfs_create_file("closures", 0400, NULL, NULL, &debug_ops);
 205 }
 206
 207 #endif
 208
 209 MODULE_AUTHOR("Kent Overstreet <koverstreet@google.com>");
 210 MODULE_LICENSE("GPL");