Something went wrong. Try again.
Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Something went wrong. Try again.
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298// SPDX-License-Identifier: GPL-2.0/* * Asynchronous refcounty things * * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com> * Copyright 2012 Google, Inc. */
#include <linux/closure.h>#include <linux/debugfs.h>#include <linux/export.h>#include <linux/rcupdate.h>#include <linux/seq_file.h>#include <linux/sched/debug.h>
static inline void closure_put_after_sub_checks(int flags){ int r = flags & CLOSURE_REMAINING_MASK;
if (WARN(flags & CLOSURE_GUARD_MASK, "closure has guard bits set: %x (%u)", flags & CLOSURE_GUARD_MASK, (unsigned) __fls(r))) r &= ~CLOSURE_GUARD_MASK;
WARN(!r && (flags & ~CLOSURE_DESTRUCTOR), "closure ref hit 0 with incorrect flags set: %x (%u)", flags & ~CLOSURE_DESTRUCTOR, (unsigned) __fls(flags));}
static inline void closure_put_after_sub(struct closure *cl, int flags){ closure_put_after_sub_checks(flags);
if (!(flags & CLOSURE_REMAINING_MASK)) { smp_acquire__after_ctrl_dep();
cl->closure_get_happened = false;
if (cl->fn && !(flags & CLOSURE_DESTRUCTOR)) { atomic_set(&cl->remaining, CLOSURE_REMAINING_INITIALIZER); closure_queue(cl); } else { struct closure *parent = cl->parent; closure_fn *destructor = cl->fn;
closure_debug_destroy(cl);
if (destructor) destructor(&cl->work);
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_release(v, &cl->remaining));}EXPORT_SYMBOL(closure_sub);
/* * closure_put - decrement a closure's refcount */void closure_put(struct closure *cl){ closure_put_after_sub(cl, atomic_dec_return_release(&cl->remaining));}EXPORT_SYMBOL(closure_put);
/* * closure_wake_up - wake up all closures on a wait list, without memory barrier */void __closure_wake_up(struct closure_waitlist *wait_list){ struct llist_node *list; struct closure *cl, *t; struct llist_node *reverse = NULL;
list = llist_del_all(&wait_list->list);
/* We first reverse the list to preserve FIFO ordering and fairness */ reverse = llist_reverse_order(list);
/* Then do the wakeups */ llist_for_each_entry_safe(cl, t, reverse, list) { closure_set_waiting(cl, 0); closure_sub(cl, CLOSURE_WAITING + 1); }}EXPORT_SYMBOL(__closure_wake_up);
/** * closure_wait - add a closure to a waitlist * @waitlist: will own a ref on @cl, which will be released when * closure_wake_up() is called on @waitlist. * @cl: closure pointer. * */bool closure_wait(struct closure_waitlist *waitlist, struct closure *cl){ if (atomic_read(&cl->remaining) & CLOSURE_WAITING) return false;
cl->closure_get_happened = true; closure_set_waiting(cl, _RET_IP_); atomic_add(CLOSURE_WAITING + 1, &cl->remaining); llist_add(&cl->list, &waitlist->list);
return true;}EXPORT_SYMBOL(closure_wait);
struct closure_syncer { struct task_struct *task; int done;};
static CLOSURE_CALLBACK(closure_sync_fn){ struct closure *cl = container_of(ws, struct closure, work); struct closure_syncer *s = cl->s; struct task_struct *p;
rcu_read_lock(); p = READ_ONCE(s->task); s->done = 1; wake_up_process(p); rcu_read_unlock();}
void __sched __closure_sync(struct closure *cl){ struct closure_syncer s = { .task = current };
cl->s = &s; continue_at(cl, closure_sync_fn, NULL);
while (1) { set_current_state(TASK_UNINTERRUPTIBLE); if (s.done) break; schedule(); }
__set_current_state(TASK_RUNNING);}EXPORT_SYMBOL(__closure_sync);
/* * closure_return_sync - finish running a closure, synchronously (i.e. waiting * for outstanding get()s to finish) and returning once closure refcount is 0. * * Unlike closure_sync() this doesn't reinit the ref to 1; subsequent * closure_get_not_zero() calls waill fail. */void __sched closure_return_sync(struct closure *cl){ struct closure_syncer s = { .task = current };
cl->s = &s; set_closure_fn(cl, closure_sync_fn, NULL);
unsigned flags = atomic_sub_return_release(1 + CLOSURE_RUNNING - CLOSURE_DESTRUCTOR, &cl->remaining);
closure_put_after_sub_checks(flags);
if (unlikely(flags & CLOSURE_REMAINING_MASK)) { while (1) { set_current_state(TASK_UNINTERRUPTIBLE); if (s.done) break; schedule(); }
__set_current_state(TASK_RUNNING); }
if (cl->parent) closure_put(cl->parent);}EXPORT_SYMBOL(closure_return_sync);
int __sched __closure_sync_timeout(struct closure *cl, unsigned long timeout){ struct closure_syncer s = { .task = current }; int ret = 0;
cl->s = &s; continue_at(cl, closure_sync_fn, NULL);
while (1) { set_current_state(TASK_UNINTERRUPTIBLE); if (s.done) break; if (!timeout) { /* * Carefully undo the continue_at() - but only if it * hasn't completed, i.e. the final closure_put() hasn't * happened yet: */ unsigned old, new, v = atomic_read(&cl->remaining); do { old = v; if (!old || (old & CLOSURE_RUNNING)) goto success;
new = old + CLOSURE_REMAINING_INITIALIZER; } while ((v = atomic_cmpxchg(&cl->remaining, old, new)) != old); ret = -ETIME; }
timeout = schedule_timeout(timeout); }success: __set_current_state(TASK_RUNNING); return ret;}EXPORT_SYMBOL(__closure_sync_timeout);
#ifdef CONFIG_DEBUG_CLOSURES
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(closure_debug_create);
void closure_debug_destroy(struct closure *cl){ unsigned long flags;
if (cl->magic == CLOSURE_MAGIC_STACK) return;
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(closure_debug_destroy);
static int debug_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: %pS -> %pS p %p r %i ", cl, (void *) cl->ip, cl->fn, cl->parent, r & CLOSURE_REMAINING_MASK);
seq_printf(f, "%s%s\n", test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&cl->work)) ? "Q" : "", r & CLOSURE_RUNNING ? "R" : "");
if (r & CLOSURE_WAITING) seq_printf(f, " W %pS\n", (void *) cl->waiting_on);
seq_putc(f, '\n'); }
spin_unlock_irq(&closure_list_lock); return 0;}
DEFINE_SHOW_ATTRIBUTE(debug);
static int __init closure_debug_init(void){ debugfs_create_file("closures", 0400, NULL, NULL, &debug_fops); return 0;}late_initcall(closure_debug_init)
#endif