GNU Linux-libre 4.19.314-gnu1
[releases.git] / drivers / md / bcache / closure.c
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
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 */
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  */
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  */
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  */
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
106 static void closure_sync_fn(struct closure *cl)
107 {
108         struct closure_syncer *s = cl->s;
109         struct task_struct *p;
110
111         rcu_read_lock();
112         p = READ_ONCE(s->task);
113         s->done = 1;
114         wake_up_process(p);
115         rcu_read_unlock();
116 }
117
118 void __sched __closure_sync(struct closure *cl)
119 {
120         struct closure_syncer s = { .task = current };
121
122         cl->s = &s;
123         continue_at(cl, closure_sync_fn, NULL);
124
125         while (1) {
126                 set_current_state(TASK_UNINTERRUPTIBLE);
127                 if (s.done)
128                         break;
129                 schedule();
130         }
131
132         __set_current_state(TASK_RUNNING);
133 }
134 EXPORT_SYMBOL(__closure_sync);
135
136 #ifdef CONFIG_BCACHE_CLOSURES_DEBUG
137
138 static LIST_HEAD(closure_list);
139 static DEFINE_SPINLOCK(closure_list_lock);
140
141 void closure_debug_create(struct closure *cl)
142 {
143         unsigned long flags;
144
145         BUG_ON(cl->magic == CLOSURE_MAGIC_ALIVE);
146         cl->magic = CLOSURE_MAGIC_ALIVE;
147
148         spin_lock_irqsave(&closure_list_lock, flags);
149         list_add(&cl->all, &closure_list);
150         spin_unlock_irqrestore(&closure_list_lock, flags);
151 }
152 EXPORT_SYMBOL(closure_debug_create);
153
154 void closure_debug_destroy(struct closure *cl)
155 {
156         unsigned long flags;
157
158         BUG_ON(cl->magic != CLOSURE_MAGIC_ALIVE);
159         cl->magic = CLOSURE_MAGIC_DEAD;
160
161         spin_lock_irqsave(&closure_list_lock, flags);
162         list_del(&cl->all);
163         spin_unlock_irqrestore(&closure_list_lock, flags);
164 }
165 EXPORT_SYMBOL(closure_debug_destroy);
166
167 static struct dentry *closure_debug;
168
169 static int debug_seq_show(struct seq_file *f, void *data)
170 {
171         struct closure *cl;
172
173         spin_lock_irq(&closure_list_lock);
174
175         list_for_each_entry(cl, &closure_list, all) {
176                 int r = atomic_read(&cl->remaining);
177
178                 seq_printf(f, "%p: %pS -> %pS p %p r %i ",
179                            cl, (void *) cl->ip, cl->fn, cl->parent,
180                            r & CLOSURE_REMAINING_MASK);
181
182                 seq_printf(f, "%s%s\n",
183                            test_bit(WORK_STRUCT_PENDING_BIT,
184                                     work_data_bits(&cl->work)) ? "Q" : "",
185                            r & CLOSURE_RUNNING  ? "R" : "");
186
187                 if (r & CLOSURE_WAITING)
188                         seq_printf(f, " W %pS\n",
189                                    (void *) cl->waiting_on);
190
191                 seq_printf(f, "\n");
192         }
193
194         spin_unlock_irq(&closure_list_lock);
195         return 0;
196 }
197
198 static int debug_seq_open(struct inode *inode, struct file *file)
199 {
200         return single_open(file, debug_seq_show, NULL);
201 }
202
203 static const struct file_operations debug_ops = {
204         .owner          = THIS_MODULE,
205         .open           = debug_seq_open,
206         .read           = seq_read,
207         .release        = single_release
208 };
209
210 void  __init closure_debug_init(void)
211 {
212         if (!IS_ERR_OR_NULL(bcache_debug))
213                 /*
214                  * it is unnecessary to check return value of
215                  * debugfs_create_file(), we should not care
216                  * about this.
217                  */
218                 closure_debug = debugfs_create_file(
219                         "closures", 0400, bcache_debug, NULL, &debug_ops);
220 }
221 #endif
222
223 MODULE_AUTHOR("Kent Overstreet <koverstreet@google.com>");
224 MODULE_LICENSE("GPL");