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
closure_put_after_sub(struct closure * cl,int flags)16 static 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 */
closure_sub(struct closure * cl,int v)44 void closure_sub(struct closure *cl, int v)
45 {
46 closure_put_after_sub(cl, atomic_sub_return(v, &cl->remaining));
47 }
48 EXPORT_SYMBOL(closure_sub);
49
50 /*
51 * closure_put - decrement a closure's refcount
52 */
closure_put(struct closure * cl)53 void closure_put(struct closure *cl)
54 {
55 closure_put_after_sub(cl, atomic_dec_return(&cl->remaining));
56 }
57 EXPORT_SYMBOL(closure_put);
58
59 /*
60 * closure_wake_up - wake up all closures on a wait list, without memory barrier
61 */
__closure_wake_up(struct closure_waitlist * wait_list)62 void __closure_wake_up(struct closure_waitlist *wait_list)
63 {
64 struct llist_node *list;
65 struct closure *cl, *t;
66 struct llist_node *reverse = NULL;
67
68 list = llist_del_all(&wait_list->list);
69
70 /* We first reverse the list to preserve FIFO ordering and fairness */
71 reverse = llist_reverse_order(list);
72
73 /* Then do the wakeups */
74 llist_for_each_entry_safe(cl, t, reverse, list) {
75 closure_set_waiting(cl, 0);
76 closure_sub(cl, CLOSURE_WAITING + 1);
77 }
78 }
79 EXPORT_SYMBOL(__closure_wake_up);
80
81 /**
82 * closure_wait - add a closure to a waitlist
83 * @waitlist: will own a ref on @cl, which will be released when
84 * closure_wake_up() is called on @waitlist.
85 * @cl: closure pointer.
86 *
87 */
closure_wait(struct closure_waitlist * waitlist,struct closure * cl)88 bool closure_wait(struct closure_waitlist *waitlist, struct closure *cl)
89 {
90 if (atomic_read(&cl->remaining) & CLOSURE_WAITING)
91 return false;
92
93 closure_set_waiting(cl, _RET_IP_);
94 atomic_add(CLOSURE_WAITING + 1, &cl->remaining);
95 llist_add(&cl->list, &waitlist->list);
96
97 return true;
98 }
99 EXPORT_SYMBOL(closure_wait);
100
101 struct closure_syncer {
102 struct task_struct *task;
103 int done;
104 };
105
closure_sync_fn(struct closure * cl)106 static void closure_sync_fn(struct closure *cl)
107 {
108 cl->s->done = 1;
109 wake_up_process(cl->s->task);
110 }
111
__closure_sync(struct closure * cl)112 void __sched __closure_sync(struct closure *cl)
113 {
114 struct closure_syncer s = { .task = current };
115
116 cl->s = &s;
117 continue_at(cl, closure_sync_fn, NULL);
118
119 while (1) {
120 set_current_state(TASK_UNINTERRUPTIBLE);
121 if (s.done)
122 break;
123 schedule();
124 }
125
126 __set_current_state(TASK_RUNNING);
127 }
128 EXPORT_SYMBOL(__closure_sync);
129
130 #ifdef CONFIG_BCACHE_CLOSURES_DEBUG
131
132 static LIST_HEAD(closure_list);
133 static DEFINE_SPINLOCK(closure_list_lock);
134
closure_debug_create(struct closure * cl)135 void closure_debug_create(struct closure *cl)
136 {
137 unsigned long flags;
138
139 BUG_ON(cl->magic == CLOSURE_MAGIC_ALIVE);
140 cl->magic = CLOSURE_MAGIC_ALIVE;
141
142 spin_lock_irqsave(&closure_list_lock, flags);
143 list_add(&cl->all, &closure_list);
144 spin_unlock_irqrestore(&closure_list_lock, flags);
145 }
146 EXPORT_SYMBOL(closure_debug_create);
147
closure_debug_destroy(struct closure * cl)148 void 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 EXPORT_SYMBOL(closure_debug_destroy);
160
161 static struct dentry *closure_debug;
162
debug_seq_show(struct seq_file * f,void * data)163 static int debug_seq_show(struct seq_file *f, void *data)
164 {
165 struct closure *cl;
166
167 spin_lock_irq(&closure_list_lock);
168
169 list_for_each_entry(cl, &closure_list, all) {
170 int r = atomic_read(&cl->remaining);
171
172 seq_printf(f, "%p: %pS -> %pS p %p r %i ",
173 cl, (void *) cl->ip, cl->fn, cl->parent,
174 r & CLOSURE_REMAINING_MASK);
175
176 seq_printf(f, "%s%s\n",
177 test_bit(WORK_STRUCT_PENDING_BIT,
178 work_data_bits(&cl->work)) ? "Q" : "",
179 r & CLOSURE_RUNNING ? "R" : "");
180
181 if (r & CLOSURE_WAITING)
182 seq_printf(f, " W %pS\n",
183 (void *) cl->waiting_on);
184
185 seq_printf(f, "\n");
186 }
187
188 spin_unlock_irq(&closure_list_lock);
189 return 0;
190 }
191
debug_seq_open(struct inode * inode,struct file * file)192 static int debug_seq_open(struct inode *inode, struct file *file)
193 {
194 return single_open(file, debug_seq_show, NULL);
195 }
196
197 static const struct file_operations debug_ops = {
198 .owner = THIS_MODULE,
199 .open = debug_seq_open,
200 .read = seq_read,
201 .release = single_release
202 };
203
closure_debug_init(void)204 void __init closure_debug_init(void)
205 {
206 if (!IS_ERR_OR_NULL(bcache_debug))
207 /*
208 * it is unnecessary to check return value of
209 * debugfs_create_file(), we should not care
210 * about this.
211 */
212 closure_debug = debugfs_create_file(
213 "closures", 0400, bcache_debug, NULL, &debug_ops);
214 }
215 #endif
216
217 MODULE_AUTHOR("Kent Overstreet <koverstreet@google.com>");
218 MODULE_LICENSE("GPL");
219
