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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899// 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);