bcache: move closures to lib/

Prep work for bcachefs - being a fork of bcache it also uses closures

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Acked-by: Coly Li <colyli@suse.de>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>

1 files changed, 204 insertions, 0 deletions

diff --git a/lib/closure.c b/lib/closure.c
new file mode 100644
index 000000000000..b38ded00b9b0
--- /dev/null
+++ b/lib/closure.c
@@ -0,0 +1,204 @@
+// 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/seq_file.h>
+#include <linux/sched/debug.h>
+
+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));
+
+	if (!r) {
+		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);
+
+			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(closure_sub);
+
+/*
+ * closure_put - decrement a closure's refcount
+ */
+void closure_put(struct closure *cl)
+{
+	closure_put_after_sub(cl, atomic_dec_return(&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;
+
+	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 void closure_sync_fn(struct closure *cl)
+{
+	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);
+
+#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;
+
+	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_puts(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