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 void closure_queue(struct closure *cl) 15 { 16 struct workqueue_struct *wq = cl->wq; 17 if (wq) { 18 INIT_WORK(&cl->work, cl->work.func); 19 BUG_ON(!queue_work(wq, &cl->work)); 20 } else 21 cl->fn(cl); 22 } 23 EXPORT_SYMBOL_GPL(closure_queue); 24 25 #define CL_FIELD(type, field) \ 26 case TYPE_ ## type: \ 27 return &container_of(cl, struct type, cl)->field 28 29 static struct closure_waitlist *closure_waitlist(struct closure *cl) 30 { 31 switch (cl->type) { 32 CL_FIELD(closure_with_waitlist, wait); 33 CL_FIELD(closure_with_waitlist_and_timer, wait); 34 default: 35 return NULL; 36 } 37 } 38 39 static struct timer_list *closure_timer(struct closure *cl) 40 { 41 switch (cl->type) { 42 CL_FIELD(closure_with_timer, timer); 43 CL_FIELD(closure_with_waitlist_and_timer, timer); 44 default: 45 return NULL; 46 } 47 } 48 49 static inline void closure_put_after_sub(struct closure *cl, int flags) 50 { 51 int r = flags & CLOSURE_REMAINING_MASK; 52 53 BUG_ON(flags & CLOSURE_GUARD_MASK); 54 BUG_ON(!r && (flags & ~(CLOSURE_DESTRUCTOR|CLOSURE_BLOCKING))); 55 56 /* Must deliver precisely one wakeup */ 57 if (r == 1 && (flags & CLOSURE_SLEEPING)) 58 wake_up_process(cl->task); 59 60 if (!r) { 61 if (cl->fn && !(flags & CLOSURE_DESTRUCTOR)) { 62 /* CLOSURE_BLOCKING might be set - clear it */ 63 atomic_set(&cl->remaining, 64 CLOSURE_REMAINING_INITIALIZER); 65 closure_queue(cl); 66 } else { 67 struct closure *parent = cl->parent; 68 struct closure_waitlist *wait = closure_waitlist(cl); 69 closure_fn *destructor = cl->fn; 70 71 closure_debug_destroy(cl); 72 73 smp_mb(); 74 atomic_set(&cl->remaining, -1); 75 76 if (wait) 77 closure_wake_up(wait); 78 79 if (destructor) 80 destructor(cl); 81 82 if (parent) 83 closure_put(parent); 84 } 85 } 86 } 87 88 /* For clearing flags with the same atomic op as a put */ 89 void closure_sub(struct closure *cl, int v) 90 { 91 closure_put_after_sub(cl, atomic_sub_return(v, &cl->remaining)); 92 } 93 EXPORT_SYMBOL_GPL(closure_sub); 94 95 void closure_put(struct closure *cl) 96 { 97 closure_put_after_sub(cl, atomic_dec_return(&cl->remaining)); 98 } 99 EXPORT_SYMBOL_GPL(closure_put); 100 101 static void set_waiting(struct closure *cl, unsigned long f) 102 { 103 #ifdef CONFIG_BCACHE_CLOSURES_DEBUG 104 cl->waiting_on = f; 105 #endif 106 } 107 108 void __closure_wake_up(struct closure_waitlist *wait_list) 109 { 110 struct llist_node *list; 111 struct closure *cl; 112 struct llist_node *reverse = NULL; 113 114 list = llist_del_all(&wait_list->list); 115 116 /* We first reverse the list to preserve FIFO ordering and fairness */ 117 118 while (list) { 119 struct llist_node *t = list; 120 list = llist_next(list); 121 122 t->next = reverse; 123 reverse = t; 124 } 125 126 /* Then do the wakeups */ 127 128 while (reverse) { 129 cl = container_of(reverse, struct closure, list); 130 reverse = llist_next(reverse); 131 132 set_waiting(cl, 0); 133 closure_sub(cl, CLOSURE_WAITING + 1); 134 } 135 } 136 EXPORT_SYMBOL_GPL(__closure_wake_up); 137 138 bool closure_wait(struct closure_waitlist *list, struct closure *cl) 139 { 140 if (atomic_read(&cl->remaining) & CLOSURE_WAITING) 141 return false; 142 143 set_waiting(cl, _RET_IP_); 144 atomic_add(CLOSURE_WAITING + 1, &cl->remaining); 145 llist_add(&cl->list, &list->list); 146 147 return true; 148 } 149 EXPORT_SYMBOL_GPL(closure_wait); 150 151 /** 152 * closure_sync() - sleep until a closure a closure has nothing left to wait on 153 * 154 * Sleeps until the refcount hits 1 - the thread that's running the closure owns 155 * the last refcount. 156 */ 157 void closure_sync(struct closure *cl) 158 { 159 while (1) { 160 __closure_start_sleep(cl); 161 closure_set_ret_ip(cl); 162 163 if ((atomic_read(&cl->remaining) & 164 CLOSURE_REMAINING_MASK) == 1) 165 break; 166 167 schedule(); 168 } 169 170 __closure_end_sleep(cl); 171 } 172 EXPORT_SYMBOL_GPL(closure_sync); 173 174 /** 175 * closure_trylock() - try to acquire the closure, without waiting 176 * @cl: closure to lock 177 * 178 * Returns true if the closure was succesfully locked. 179 */ 180 bool closure_trylock(struct closure *cl, struct closure *parent) 181 { 182 if (atomic_cmpxchg(&cl->remaining, -1, 183 CLOSURE_REMAINING_INITIALIZER) != -1) 184 return false; 185 186 closure_set_ret_ip(cl); 187 188 smp_mb(); 189 cl->parent = parent; 190 if (parent) 191 closure_get(parent); 192 193 closure_debug_create(cl); 194 return true; 195 } 196 EXPORT_SYMBOL_GPL(closure_trylock); 197 198 void __closure_lock(struct closure *cl, struct closure *parent, 199 struct closure_waitlist *wait_list) 200 { 201 struct closure wait; 202 closure_init_stack(&wait); 203 204 while (1) { 205 if (closure_trylock(cl, parent)) 206 return; 207 208 closure_wait_event_sync(wait_list, &wait, 209 atomic_read(&cl->remaining) == -1); 210 } 211 } 212 EXPORT_SYMBOL_GPL(__closure_lock); 213 214 static void closure_delay_timer_fn(unsigned long data) 215 { 216 struct closure *cl = (struct closure *) data; 217 closure_sub(cl, CLOSURE_TIMER + 1); 218 } 219 220 void do_closure_timer_init(struct closure *cl) 221 { 222 struct timer_list *timer = closure_timer(cl); 223 224 init_timer(timer); 225 timer->data = (unsigned long) cl; 226 timer->function = closure_delay_timer_fn; 227 } 228 EXPORT_SYMBOL_GPL(do_closure_timer_init); 229 230 bool __closure_delay(struct closure *cl, unsigned long delay, 231 struct timer_list *timer) 232 { 233 if (atomic_read(&cl->remaining) & CLOSURE_TIMER) 234 return false; 235 236 BUG_ON(timer_pending(timer)); 237 238 timer->expires = jiffies + delay; 239 240 atomic_add(CLOSURE_TIMER + 1, &cl->remaining); 241 add_timer(timer); 242 return true; 243 } 244 EXPORT_SYMBOL_GPL(__closure_delay); 245 246 void __closure_flush(struct closure *cl, struct timer_list *timer) 247 { 248 if (del_timer(timer)) 249 closure_sub(cl, CLOSURE_TIMER + 1); 250 } 251 EXPORT_SYMBOL_GPL(__closure_flush); 252 253 void __closure_flush_sync(struct closure *cl, struct timer_list *timer) 254 { 255 if (del_timer_sync(timer)) 256 closure_sub(cl, CLOSURE_TIMER + 1); 257 } 258 EXPORT_SYMBOL_GPL(__closure_flush_sync); 259 260 #ifdef CONFIG_BCACHE_CLOSURES_DEBUG 261 262 static LIST_HEAD(closure_list); 263 static DEFINE_SPINLOCK(closure_list_lock); 264 265 void closure_debug_create(struct closure *cl) 266 { 267 unsigned long flags; 268 269 BUG_ON(cl->magic == CLOSURE_MAGIC_ALIVE); 270 cl->magic = CLOSURE_MAGIC_ALIVE; 271 272 spin_lock_irqsave(&closure_list_lock, flags); 273 list_add(&cl->all, &closure_list); 274 spin_unlock_irqrestore(&closure_list_lock, flags); 275 } 276 EXPORT_SYMBOL_GPL(closure_debug_create); 277 278 void closure_debug_destroy(struct closure *cl) 279 { 280 unsigned long flags; 281 282 BUG_ON(cl->magic != CLOSURE_MAGIC_ALIVE); 283 cl->magic = CLOSURE_MAGIC_DEAD; 284 285 spin_lock_irqsave(&closure_list_lock, flags); 286 list_del(&cl->all); 287 spin_unlock_irqrestore(&closure_list_lock, flags); 288 } 289 EXPORT_SYMBOL_GPL(closure_debug_destroy); 290 291 static struct dentry *debug; 292 293 #define work_data_bits(work) ((unsigned long *)(&(work)->data)) 294 295 static int debug_seq_show(struct seq_file *f, void *data) 296 { 297 struct closure *cl; 298 spin_lock_irq(&closure_list_lock); 299 300 list_for_each_entry(cl, &closure_list, all) { 301 int r = atomic_read(&cl->remaining); 302 303 seq_printf(f, "%p: %pF -> %pf p %p r %i ", 304 cl, (void *) cl->ip, cl->fn, cl->parent, 305 r & CLOSURE_REMAINING_MASK); 306 307 seq_printf(f, "%s%s%s%s%s%s\n", 308 test_bit(WORK_STRUCT_PENDING, 309 work_data_bits(&cl->work)) ? "Q" : "", 310 r & CLOSURE_RUNNING ? "R" : "", 311 r & CLOSURE_BLOCKING ? "B" : "", 312 r & CLOSURE_STACK ? "S" : "", 313 r & CLOSURE_SLEEPING ? "Sl" : "", 314 r & CLOSURE_TIMER ? "T" : ""); 315 316 if (r & CLOSURE_WAITING) 317 seq_printf(f, " W %pF\n", 318 (void *) cl->waiting_on); 319 320 seq_printf(f, "\n"); 321 } 322 323 spin_unlock_irq(&closure_list_lock); 324 return 0; 325 } 326 327 static int debug_seq_open(struct inode *inode, struct file *file) 328 { 329 return single_open(file, debug_seq_show, NULL); 330 } 331 332 static const struct file_operations debug_ops = { 333 .owner = THIS_MODULE, 334 .open = debug_seq_open, 335 .read = seq_read, 336 .release = single_release 337 }; 338 339 void __init closure_debug_init(void) 340 { 341 debug = debugfs_create_file("closures", 0400, NULL, NULL, &debug_ops); 342 } 343 344 #endif 345 346 MODULE_AUTHOR("Kent Overstreet <koverstreet@google.com>"); 347 MODULE_LICENSE("GPL"); 348