1 // SPDX-License-Identifier: GPL-2.0
3 * Asynchronous refcounty things
5 * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
6 * Copyright 2012 Google, Inc.
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>
16 static inline void closure_put_after_sub(struct closure *cl, int flags)
18 int r = flags & CLOSURE_REMAINING_MASK;
20 if ((flags & CLOSURE_GUARD_MASK) ||
21 (!r && (flags & ~CLOSURE_DESTRUCTOR)))
22 panic("closure_put_after_sub: bogus flags %x remaining %i", flags, r);
25 smp_acquire__after_ctrl_dep();
27 cl->closure_get_happened = false;
29 if (cl->fn && !(flags & CLOSURE_DESTRUCTOR)) {
30 atomic_set(&cl->remaining,
31 CLOSURE_REMAINING_INITIALIZER);
34 struct closure *parent = cl->parent;
35 closure_fn *destructor = cl->fn;
37 closure_debug_destroy(cl);
48 /* For clearing flags with the same atomic op as a put */
49 void closure_sub(struct closure *cl, int v)
51 closure_put_after_sub(cl, atomic_sub_return_release(v, &cl->remaining));
53 EXPORT_SYMBOL(closure_sub);
56 * closure_put - decrement a closure's refcount
58 void closure_put(struct closure *cl)
60 closure_put_after_sub(cl, atomic_dec_return_release(&cl->remaining));
62 EXPORT_SYMBOL(closure_put);
65 * closure_wake_up - wake up all closures on a wait list, without memory barrier
67 void __closure_wake_up(struct closure_waitlist *wait_list)
69 struct llist_node *list;
70 struct closure *cl, *t;
71 struct llist_node *reverse = NULL;
73 list = llist_del_all(&wait_list->list);
75 /* We first reverse the list to preserve FIFO ordering and fairness */
76 reverse = llist_reverse_order(list);
78 /* Then do the wakeups */
79 llist_for_each_entry_safe(cl, t, reverse, list) {
80 closure_set_waiting(cl, 0);
81 closure_sub(cl, CLOSURE_WAITING + 1);
84 EXPORT_SYMBOL(__closure_wake_up);
87 * closure_wait - add a closure to a waitlist
88 * @waitlist: will own a ref on @cl, which will be released when
89 * closure_wake_up() is called on @waitlist.
90 * @cl: closure pointer.
93 bool closure_wait(struct closure_waitlist *waitlist, struct closure *cl)
95 if (atomic_read(&cl->remaining) & CLOSURE_WAITING)
98 cl->closure_get_happened = true;
99 closure_set_waiting(cl, _RET_IP_);
100 atomic_add(CLOSURE_WAITING + 1, &cl->remaining);
101 llist_add(&cl->list, &waitlist->list);
105 EXPORT_SYMBOL(closure_wait);
107 struct closure_syncer {
108 struct task_struct *task;
112 static void closure_sync_fn(struct closure *cl)
114 struct closure_syncer *s = cl->s;
115 struct task_struct *p;
118 p = READ_ONCE(s->task);
124 void __sched __closure_sync(struct closure *cl)
126 struct closure_syncer s = { .task = current };
129 continue_at(cl, closure_sync_fn, NULL);
132 set_current_state(TASK_UNINTERRUPTIBLE);
138 __set_current_state(TASK_RUNNING);
140 EXPORT_SYMBOL(__closure_sync);
142 #ifdef CONFIG_DEBUG_CLOSURES
144 static LIST_HEAD(closure_list);
145 static DEFINE_SPINLOCK(closure_list_lock);
147 void closure_debug_create(struct closure *cl)
151 BUG_ON(cl->magic == CLOSURE_MAGIC_ALIVE);
152 cl->magic = CLOSURE_MAGIC_ALIVE;
154 spin_lock_irqsave(&closure_list_lock, flags);
155 list_add(&cl->all, &closure_list);
156 spin_unlock_irqrestore(&closure_list_lock, flags);
158 EXPORT_SYMBOL(closure_debug_create);
160 void closure_debug_destroy(struct closure *cl)
164 BUG_ON(cl->magic != CLOSURE_MAGIC_ALIVE);
165 cl->magic = CLOSURE_MAGIC_DEAD;
167 spin_lock_irqsave(&closure_list_lock, flags);
169 spin_unlock_irqrestore(&closure_list_lock, flags);
171 EXPORT_SYMBOL(closure_debug_destroy);
173 static int debug_show(struct seq_file *f, void *data)
177 spin_lock_irq(&closure_list_lock);
179 list_for_each_entry(cl, &closure_list, all) {
180 int r = atomic_read(&cl->remaining);
182 seq_printf(f, "%p: %pS -> %pS p %p r %i ",
183 cl, (void *) cl->ip, cl->fn, cl->parent,
184 r & CLOSURE_REMAINING_MASK);
186 seq_printf(f, "%s%s\n",
187 test_bit(WORK_STRUCT_PENDING_BIT,
188 work_data_bits(&cl->work)) ? "Q" : "",
189 r & CLOSURE_RUNNING ? "R" : "");
191 if (r & CLOSURE_WAITING)
192 seq_printf(f, " W %pS\n",
193 (void *) cl->waiting_on);
198 spin_unlock_irq(&closure_list_lock);
202 DEFINE_SHOW_ATTRIBUTE(debug);
204 static int __init closure_debug_init(void)
206 debugfs_create_file("closures", 0400, NULL, NULL, &debug_fops);
209 late_initcall(closure_debug_init)