// SPDX-License-Identifier: GPL-2.0
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/once.h>
#include <linux/random.h>
#include <linux/module.h>

struct once_work {
        struct work_struct work;
        struct static_key_true *key;
        struct module *module;
};

static void once_deferred(struct work_struct *w)
{
        struct once_work *work;

        work = container_of(w, struct once_work, work);
        BUG_ON(!static_key_enabled(work->key));
        static_branch_disable(work->key);
        module_put(work->module);
        kfree(work);
}

static void once_disable_jump(struct static_key_true *key, struct module *mod)
{
        struct once_work *w;

        w = kmalloc_obj(*w, GFP_ATOMIC);
        if (!w)
                return;

        INIT_WORK(&w->work, once_deferred);
        w->key = key;
        w->module = mod;
        __module_get(mod);
        schedule_work(&w->work);
}

static DEFINE_SPINLOCK(once_lock);

bool __do_once_start(bool *done, unsigned long *flags)
        __acquires(once_lock)
{
        spin_lock_irqsave(&once_lock, *flags);
        if (*done) {
                spin_unlock_irqrestore(&once_lock, *flags);
                /* Keep sparse happy by restoring an even lock count on
                 * this lock. In case we return here, we don't call into
                 * __do_once_done but return early in the DO_ONCE() macro.
                 */
                __acquire(once_lock);
                return false;
        }

        return true;
}
EXPORT_SYMBOL(__do_once_start);

void __do_once_done(bool *done, struct static_key_true *once_key,
                    unsigned long *flags, struct module *mod)
        __releases(once_lock)
{
        *done = true;
        spin_unlock_irqrestore(&once_lock, *flags);
        once_disable_jump(once_key, mod);
}
EXPORT_SYMBOL(__do_once_done);

static DEFINE_MUTEX(once_mutex);

bool __do_once_sleepable_start(bool *done)
        __acquires(once_mutex)
{
        mutex_lock(&once_mutex);
        if (*done) {
                mutex_unlock(&once_mutex);
                /* Keep sparse happy by restoring an even lock count on
                 * this mutex. In case we return here, we don't call into
                 * __do_once_done but return early in the DO_ONCE_SLEEPABLE() macro.
                 */
                __acquire(once_mutex);
                return false;
        }

        return true;
}
EXPORT_SYMBOL(__do_once_sleepable_start);

void __do_once_sleepable_done(bool *done, struct static_key_true *once_key,
                         struct module *mod)
        __releases(once_mutex)
{
        *done = true;
        mutex_unlock(&once_mutex);
        static_branch_disable(once_key);
}
EXPORT_SYMBOL(__do_once_sleepable_done);