blob: 9aba2017f0d1685ac5858ccf716c1f829681c853 [file] [log] [blame]
/*
* Asynchronous refcounty things
*
* Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
* Copyright 2012 Google, Inc.
*/
#include <linux/debugfs.h>
#include <linux/module.h>
#include <linux/seq_file.h>
#include "closure.h"
void closure_queue(struct closure *cl)
{
struct workqueue_struct *wq = cl->wq;
if (wq) {
INIT_WORK(&cl->work, cl->work.func);
BUG_ON(!queue_work(wq, &cl->work));
} else
cl->fn(cl);
}
EXPORT_SYMBOL_GPL(closure_queue);
#define CL_FIELD(type, field) \
case TYPE_ ## type: \
return &container_of(cl, struct type, cl)->field
static struct closure_waitlist *closure_waitlist(struct closure *cl)
{
switch (cl->type) {
CL_FIELD(closure_with_waitlist, wait);
CL_FIELD(closure_with_waitlist_and_timer, wait);
default:
return NULL;
}
}
static struct timer_list *closure_timer(struct closure *cl)
{
switch (cl->type) {
CL_FIELD(closure_with_timer, timer);
CL_FIELD(closure_with_waitlist_and_timer, timer);
default:
return NULL;
}
}
static inline void closure_put_after_sub(struct closure *cl, int flags)
{
int r = flags & CLOSURE_REMAINING_MASK;
BUG_ON(flags & CLOSURE_GUARD_MASK);
BUG_ON(!r && (flags & ~(CLOSURE_DESTRUCTOR|CLOSURE_BLOCKING)));
/* Must deliver precisely one wakeup */
if (r == 1 && (flags & CLOSURE_SLEEPING))
wake_up_process(cl->task);
if (!r) {
if (cl->fn && !(flags & CLOSURE_DESTRUCTOR)) {
/* CLOSURE_BLOCKING might be set - clear it */
atomic_set(&cl->remaining,
CLOSURE_REMAINING_INITIALIZER);
closure_queue(cl);
} else {
struct closure *parent = cl->parent;
struct closure_waitlist *wait = closure_waitlist(cl);
closure_fn *destructor = cl->fn;
closure_debug_destroy(cl);
smp_mb();
atomic_set(&cl->remaining, -1);
if (wait)
closure_wake_up(wait);
if (destructor)
destructor(cl);
if (parent)
closure_put(parent);
}
}
}
/* For clearing flags with the same atomic op as a put */
void closure_sub(struct closure *cl, int v)
{
closure_put_after_sub(cl, atomic_sub_return(v, &cl->remaining));
}
EXPORT_SYMBOL_GPL(closure_sub);
void closure_put(struct closure *cl)
{
closure_put_after_sub(cl, atomic_dec_return(&cl->remaining));
}
EXPORT_SYMBOL_GPL(closure_put);
static void set_waiting(struct closure *cl, unsigned long f)
{
#ifdef CONFIG_BCACHE_CLOSURES_DEBUG
cl->waiting_on = f;
#endif
}
void __closure_wake_up(struct closure_waitlist *wait_list)
{
struct llist_node *list;
struct closure *cl;
struct llist_node *reverse = NULL;
list = llist_del_all(&wait_list->list);
/* We first reverse the list to preserve FIFO ordering and fairness */
while (list) {
struct llist_node *t = list;
list = llist_next(list);
t->next = reverse;
reverse = t;
}
/* Then do the wakeups */
while (reverse) {
cl = container_of(reverse, struct closure, list);
reverse = llist_next(reverse);
set_waiting(cl, 0);
closure_sub(cl, CLOSURE_WAITING + 1);
}
}
EXPORT_SYMBOL_GPL(__closure_wake_up);
bool closure_wait(struct closure_waitlist *list, struct closure *cl)
{
if (atomic_read(&cl->remaining) & CLOSURE_WAITING)
return false;
set_waiting(cl, _RET_IP_);
atomic_add(CLOSURE_WAITING + 1, &cl->remaining);
llist_add(&cl->list, &list->list);
return true;
}
EXPORT_SYMBOL_GPL(closure_wait);
/**
* closure_sync() - sleep until a closure a closure has nothing left to wait on
*
* Sleeps until the refcount hits 1 - the thread that's running the closure owns
* the last refcount.
*/
void closure_sync(struct closure *cl)
{
while (1) {
__closure_start_sleep(cl);
closure_set_ret_ip(cl);
if ((atomic_read(&cl->remaining) &
CLOSURE_REMAINING_MASK) == 1)
break;
schedule();
}
__closure_end_sleep(cl);
}
EXPORT_SYMBOL_GPL(closure_sync);
/**
* closure_trylock() - try to acquire the closure, without waiting
* @cl: closure to lock
*
* Returns true if the closure was succesfully locked.
*/
bool closure_trylock(struct closure *cl, struct closure *parent)
{
if (atomic_cmpxchg(&cl->remaining, -1,
CLOSURE_REMAINING_INITIALIZER) != -1)
return false;
closure_set_ret_ip(cl);
smp_mb();
cl->parent = parent;
if (parent)
closure_get(parent);
closure_debug_create(cl);
return true;
}
EXPORT_SYMBOL_GPL(closure_trylock);
void __closure_lock(struct closure *cl, struct closure *parent,
struct closure_waitlist *wait_list)
{
struct closure wait;
closure_init_stack(&wait);
while (1) {
if (closure_trylock(cl, parent))
return;
closure_wait_event_sync(wait_list, &wait,
atomic_read(&cl->remaining) == -1);
}
}
EXPORT_SYMBOL_GPL(__closure_lock);
static void closure_delay_timer_fn(unsigned long data)
{
struct closure *cl = (struct closure *) data;
closure_sub(cl, CLOSURE_TIMER + 1);
}
void do_closure_timer_init(struct closure *cl)
{
struct timer_list *timer = closure_timer(cl);
init_timer(timer);
timer->data = (unsigned long) cl;
timer->function = closure_delay_timer_fn;
}
EXPORT_SYMBOL_GPL(do_closure_timer_init);
bool __closure_delay(struct closure *cl, unsigned long delay,
struct timer_list *timer)
{
if (atomic_read(&cl->remaining) & CLOSURE_TIMER)
return false;
BUG_ON(timer_pending(timer));
timer->expires = jiffies + delay;
atomic_add(CLOSURE_TIMER + 1, &cl->remaining);
add_timer(timer);
return true;
}
EXPORT_SYMBOL_GPL(__closure_delay);
void __closure_flush(struct closure *cl, struct timer_list *timer)
{
if (del_timer(timer))
closure_sub(cl, CLOSURE_TIMER + 1);
}
EXPORT_SYMBOL_GPL(__closure_flush);
void __closure_flush_sync(struct closure *cl, struct timer_list *timer)
{
if (del_timer_sync(timer))
closure_sub(cl, CLOSURE_TIMER + 1);
}
EXPORT_SYMBOL_GPL(__closure_flush_sync);
#ifdef CONFIG_BCACHE_CLOSURES_DEBUG
static LIST_HEAD(closure_list);
static DEFINE_SPINLOCK(closure_list_lock);
void closure_debug_create(struct closure *cl)
{
unsigned long flags;
BUG_ON(cl->magic == CLOSURE_MAGIC_ALIVE);
cl->magic = CLOSURE_MAGIC_ALIVE;
spin_lock_irqsave(&closure_list_lock, flags);
list_add(&cl->all, &closure_list);
spin_unlock_irqrestore(&closure_list_lock, flags);
}
EXPORT_SYMBOL_GPL(closure_debug_create);
void closure_debug_destroy(struct closure *cl)
{
unsigned long flags;
BUG_ON(cl->magic != CLOSURE_MAGIC_ALIVE);
cl->magic = CLOSURE_MAGIC_DEAD;
spin_lock_irqsave(&closure_list_lock, flags);
list_del(&cl->all);
spin_unlock_irqrestore(&closure_list_lock, flags);
}
EXPORT_SYMBOL_GPL(closure_debug_destroy);
static struct dentry *debug;
#define work_data_bits(work) ((unsigned long *)(&(work)->data))
static int debug_seq_show(struct seq_file *f, void *data)
{
struct closure *cl;
spin_lock_irq(&closure_list_lock);
list_for_each_entry(cl, &closure_list, all) {
int r = atomic_read(&cl->remaining);
seq_printf(f, "%p: %pF -> %pf p %p r %i ",
cl, (void *) cl->ip, cl->fn, cl->parent,
r & CLOSURE_REMAINING_MASK);
seq_printf(f, "%s%s%s%s%s%s\n",
test_bit(WORK_STRUCT_PENDING,
work_data_bits(&cl->work)) ? "Q" : "",
r & CLOSURE_RUNNING ? "R" : "",
r & CLOSURE_BLOCKING ? "B" : "",
r & CLOSURE_STACK ? "S" : "",
r & CLOSURE_SLEEPING ? "Sl" : "",
r & CLOSURE_TIMER ? "T" : "");
if (r & CLOSURE_WAITING)
seq_printf(f, " W %pF\n",
(void *) cl->waiting_on);
seq_printf(f, "\n");
}
spin_unlock_irq(&closure_list_lock);
return 0;
}
static int debug_seq_open(struct inode *inode, struct file *file)
{
return single_open(file, debug_seq_show, NULL);
}
static const struct file_operations debug_ops = {
.owner = THIS_MODULE,
.open = debug_seq_open,
.read = seq_read,
.release = single_release
};
void __init closure_debug_init(void)
{
debug = debugfs_create_file("closures", 0400, NULL, NULL, &debug_ops);
}
#endif
MODULE_AUTHOR("Kent Overstreet <koverstreet@google.com>");
MODULE_LICENSE("GPL");