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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Asynchronous refcounty things
4 *
5 * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
6 * Copyright 2012 Google, Inc.
7 */
8
9#include <linux/debugfs.h>
10#include <linux/module.h>
11#include <linux/seq_file.h>
12#include <linux/sched/debug.h>
13
14#include "closure.h"
15
16static inline void closure_put_after_sub(struct closure *cl, int flags)
17{
18 int r = flags & CLOSURE_REMAINING_MASK;
19
20 BUG_ON(flags & CLOSURE_GUARD_MASK);
21 BUG_ON(!r && (flags & ~CLOSURE_DESTRUCTOR));
22
23 if (!r) {
24 if (cl->fn && !(flags & CLOSURE_DESTRUCTOR)) {
25 atomic_set(&cl->remaining,
26 CLOSURE_REMAINING_INITIALIZER);
27 closure_queue(cl);
28 } else {
29 struct closure *parent = cl->parent;
30 closure_fn *destructor = cl->fn;
31
32 closure_debug_destroy(cl);
33
34 if (destructor)
35 destructor(cl);
36
37 if (parent)
38 closure_put(parent);
39 }
40 }
41}
42
43/* For clearing flags with the same atomic op as a put */
44void closure_sub(struct closure *cl, int v)
45{
46 closure_put_after_sub(cl, atomic_sub_return(v, &cl->remaining));
47}
48
49/*
50 * closure_put - decrement a closure's refcount
51 */
52void closure_put(struct closure *cl)
53{
54 closure_put_after_sub(cl, atomic_dec_return(&cl->remaining));
55}
56
57/*
58 * closure_wake_up - wake up all closures on a wait list, without memory barrier
59 */
60void __closure_wake_up(struct closure_waitlist *wait_list)
61{
62 struct llist_node *list;
63 struct closure *cl, *t;
64 struct llist_node *reverse = NULL;
65
66 list = llist_del_all(&wait_list->list);
67
68 /* We first reverse the list to preserve FIFO ordering and fairness */
69 reverse = llist_reverse_order(list);
70
71 /* Then do the wakeups */
72 llist_for_each_entry_safe(cl, t, reverse, list) {
73 closure_set_waiting(cl, 0);
74 closure_sub(cl, CLOSURE_WAITING + 1);
75 }
76}
77
78/**
79 * closure_wait - add a closure to a waitlist
80 * @waitlist: will own a ref on @cl, which will be released when
81 * closure_wake_up() is called on @waitlist.
82 * @cl: closure pointer.
83 *
84 */
85bool closure_wait(struct closure_waitlist *waitlist, struct closure *cl)
86{
87 if (atomic_read(&cl->remaining) & CLOSURE_WAITING)
88 return false;
89
90 closure_set_waiting(cl, _RET_IP_);
91 atomic_add(CLOSURE_WAITING + 1, &cl->remaining);
92 llist_add(&cl->list, &waitlist->list);
93
94 return true;
95}
96
97struct closure_syncer {
98 struct task_struct *task;
99 int done;
100};
101
102static void closure_sync_fn(struct closure *cl)
103{
104 struct closure_syncer *s = cl->s;
105 struct task_struct *p;
106
107 rcu_read_lock();
108 p = READ_ONCE(s->task);
109 s->done = 1;
110 wake_up_process(p);
111 rcu_read_unlock();
112}
113
114void __sched __closure_sync(struct closure *cl)
115{
116 struct closure_syncer s = { .task = current };
117
118 cl->s = &s;
119 continue_at(cl, closure_sync_fn, NULL);
120
121 while (1) {
122 set_current_state(TASK_UNINTERRUPTIBLE);
123 if (s.done)
124 break;
125 schedule();
126 }
127
128 __set_current_state(TASK_RUNNING);
129}
130
131#ifdef CONFIG_BCACHE_CLOSURES_DEBUG
132
133static LIST_HEAD(closure_list);
134static DEFINE_SPINLOCK(closure_list_lock);
135
136void closure_debug_create(struct closure *cl)
137{
138 unsigned long flags;
139
140 BUG_ON(cl->magic == CLOSURE_MAGIC_ALIVE);
141 cl->magic = CLOSURE_MAGIC_ALIVE;
142
143 spin_lock_irqsave(&closure_list_lock, flags);
144 list_add(&cl->all, &closure_list);
145 spin_unlock_irqrestore(&closure_list_lock, flags);
146}
147
148void closure_debug_destroy(struct closure *cl)
149{
150 unsigned long flags;
151
152 BUG_ON(cl->magic != CLOSURE_MAGIC_ALIVE);
153 cl->magic = CLOSURE_MAGIC_DEAD;
154
155 spin_lock_irqsave(&closure_list_lock, flags);
156 list_del(&cl->all);
157 spin_unlock_irqrestore(&closure_list_lock, flags);
158}
159
160static struct dentry *closure_debug;
161
162static int debug_show(struct seq_file *f, void *data)
163{
164 struct closure *cl;
165
166 spin_lock_irq(&closure_list_lock);
167
168 list_for_each_entry(cl, &closure_list, all) {
169 int r = atomic_read(&cl->remaining);
170
171 seq_printf(f, "%p: %pS -> %pS p %p r %i ",
172 cl, (void *) cl->ip, cl->fn, cl->parent,
173 r & CLOSURE_REMAINING_MASK);
174
175 seq_printf(f, "%s%s\n",
176 test_bit(WORK_STRUCT_PENDING_BIT,
177 work_data_bits(&cl->work)) ? "Q" : "",
178 r & CLOSURE_RUNNING ? "R" : "");
179
180 if (r & CLOSURE_WAITING)
181 seq_printf(f, " W %pS\n",
182 (void *) cl->waiting_on);
183
184 seq_printf(f, "\n");
185 }
186
187 spin_unlock_irq(&closure_list_lock);
188 return 0;
189}
190
191DEFINE_SHOW_ATTRIBUTE(debug);
192
193void __init closure_debug_init(void)
194{
195 if (!IS_ERR_OR_NULL(bcache_debug))
196 /*
197 * it is unnecessary to check return value of
198 * debugfs_create_file(), we should not care
199 * about this.
200 */
201 closure_debug = debugfs_create_file(
202 "closures", 0400, bcache_debug, NULL, &debug_fops);
203}
204#endif
205
206MODULE_AUTHOR("Kent Overstreet <koverstreet@google.com>");
207MODULE_LICENSE("GPL");
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
14static 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 */
46void closure_sub(struct closure *cl, int v)
47{
48 closure_put_after_sub(cl, atomic_sub_return(v, &cl->remaining));
49}
50EXPORT_SYMBOL(closure_sub);
51
52/**
53 * closure_put - decrement a closure's refcount
54 */
55void closure_put(struct closure *cl)
56{
57 closure_put_after_sub(cl, atomic_dec_return(&cl->remaining));
58}
59EXPORT_SYMBOL(closure_put);
60
61/**
62 * closure_wake_up - wake up all closures on a wait list, without memory barrier
63 */
64void __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}
92EXPORT_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 */
101bool 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}
112EXPORT_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 */
120void 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}
135EXPORT_SYMBOL(closure_sync);
136
137#ifdef CONFIG_BCACHE_CLOSURES_DEBUG
138
139static LIST_HEAD(closure_list);
140static DEFINE_SPINLOCK(closure_list_lock);
141
142void 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}
153EXPORT_SYMBOL(closure_debug_create);
154
155void 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}
166EXPORT_SYMBOL(closure_debug_destroy);
167
168static struct dentry *debug;
169
170#define work_data_bits(work) ((unsigned long *)(&(work)->data))
171
172static 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
202static int debug_seq_open(struct inode *inode, struct file *file)
203{
204 return single_open(file, debug_seq_show, NULL);
205}
206
207static 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
214void __init closure_debug_init(void)
215{
216 debug = debugfs_create_file("closures", 0400, NULL, NULL, &debug_ops);
217}
218
219#endif
220
221MODULE_AUTHOR("Kent Overstreet <koverstreet@google.com>");
222MODULE_LICENSE("GPL");