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 /* Must deliver precisely one wakeup */ 22 if (r == 1 && (flags & CLOSURE_SLEEPING)) 23 wake_up_process(cl->task); 24 25 if (!r) { 26 if (cl->fn && !(flags & CLOSURE_DESTRUCTOR)) { 27 atomic_set(&cl->remaining, 28 CLOSURE_REMAINING_INITIALIZER); 29 closure_queue(cl); 30 } else { 31 struct closure *parent = cl->parent; 32 closure_fn *destructor = cl->fn; 33 34 closure_debug_destroy(cl); 35 36 if (destructor) 37 destructor(cl); 38 39 if (parent) 40 closure_put(parent); 41 } 42 } 43 } 44 45 /* For clearing flags with the same atomic op as a put */ 46 void closure_sub(struct closure *cl, int v) 47 { 48 closure_put_after_sub(cl, atomic_sub_return(v, &cl->remaining)); 49 } 50 EXPORT_SYMBOL(closure_sub); 51 52 /** 53 * closure_put - decrement a closure's refcount 54 */ 55 void closure_put(struct closure *cl) 56 { 57 closure_put_after_sub(cl, atomic_dec_return(&cl->remaining)); 58 } 59 EXPORT_SYMBOL(closure_put); 60 61 /** 62 * closure_wake_up - wake up all closures on a wait list, without memory barrier 63 */ 64 void __closure_wake_up(struct closure_waitlist *wait_list) 65 { 66 struct llist_node *list; 67 struct closure *cl; 68 struct llist_node *reverse = NULL; 69 70 list = llist_del_all(&wait_list->list); 71 72 /* We first reverse the list to preserve FIFO ordering and fairness */ 73 74 while (list) { 75 struct llist_node *t = list; 76 list = llist_next(list); 77 78 t->next = reverse; 79 reverse = t; 80 } 81 82 /* Then do the wakeups */ 83 84 while (reverse) { 85 cl = container_of(reverse, struct closure, list); 86 reverse = llist_next(reverse); 87 88 closure_set_waiting(cl, 0); 89 closure_sub(cl, CLOSURE_WAITING + 1); 90 } 91 } 92 EXPORT_SYMBOL(__closure_wake_up); 93 94 /** 95 * closure_wait - add a closure to a waitlist 96 * 97 * @waitlist will own a ref on @cl, which will be released when 98 * closure_wake_up() is called on @waitlist. 99 * 100 */ 101 bool closure_wait(struct closure_waitlist *waitlist, struct closure *cl) 102 { 103 if (atomic_read(&cl->remaining) & CLOSURE_WAITING) 104 return false; 105 106 closure_set_waiting(cl, _RET_IP_); 107 atomic_add(CLOSURE_WAITING + 1, &cl->remaining); 108 llist_add(&cl->list, &waitlist->list); 109 110 return true; 111 } 112 EXPORT_SYMBOL(closure_wait); 113 114 /** 115 * closure_sync - sleep until a closure a closure has nothing left to wait on 116 * 117 * Sleeps until the refcount hits 1 - the thread that's running the closure owns 118 * the last refcount. 119 */ 120 void closure_sync(struct closure *cl) 121 { 122 while (1) { 123 __closure_start_sleep(cl); 124 closure_set_ret_ip(cl); 125 126 if ((atomic_read(&cl->remaining) & 127 CLOSURE_REMAINING_MASK) == 1) 128 break; 129 130 schedule(); 131 } 132 133 __closure_end_sleep(cl); 134 } 135 EXPORT_SYMBOL(closure_sync); 136 137 #ifdef CONFIG_BCACHE_CLOSURES_DEBUG 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 struct dentry *debug; 169 170 #define work_data_bits(work) ((unsigned long *)(&(work)->data)) 171 172 static int debug_seq_show(struct seq_file *f, void *data) 173 { 174 struct closure *cl; 175 spin_lock_irq(&closure_list_lock); 176 177 list_for_each_entry(cl, &closure_list, all) { 178 int r = atomic_read(&cl->remaining); 179 180 seq_printf(f, "%p: %pF -> %pf p %p r %i ", 181 cl, (void *) cl->ip, cl->fn, cl->parent, 182 r & CLOSURE_REMAINING_MASK); 183 184 seq_printf(f, "%s%s%s%s\n", 185 test_bit(WORK_STRUCT_PENDING, 186 work_data_bits(&cl->work)) ? "Q" : "", 187 r & CLOSURE_RUNNING ? "R" : "", 188 r & CLOSURE_STACK ? "S" : "", 189 r & CLOSURE_SLEEPING ? "Sl" : ""); 190 191 if (r & CLOSURE_WAITING) 192 seq_printf(f, " W %pF\n", 193 (void *) cl->waiting_on); 194 195 seq_printf(f, "\n"); 196 } 197 198 spin_unlock_irq(&closure_list_lock); 199 return 0; 200 } 201 202 static int debug_seq_open(struct inode *inode, struct file *file) 203 { 204 return single_open(file, debug_seq_show, NULL); 205 } 206 207 static const struct file_operations debug_ops = { 208 .owner = THIS_MODULE, 209 .open = debug_seq_open, 210 .read = seq_read, 211 .release = single_release 212 }; 213 214 void __init closure_debug_init(void) 215 { 216 debug = debugfs_create_file("closures", 0400, NULL, NULL, &debug_ops); 217 } 218 219 #endif 220 221 MODULE_AUTHOR("Kent Overstreet <koverstreet@google.com>"); 222 MODULE_LICENSE("GPL"); 223