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