Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  1) // SPDX-License-Identifier: GPL-2.0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  2) #include <linux/slab.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  3) #include <linux/spinlock.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  4) #include <linux/once.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  5) #include <linux/random.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  6) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  7) struct once_work {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  8) 	struct work_struct work;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  9) 	struct static_key_true *key;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) static void once_deferred(struct work_struct *w)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) 	struct once_work *work;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) 	work = container_of(w, struct once_work, work);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) 	BUG_ON(!static_key_enabled(work->key));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) 	static_branch_disable(work->key);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) 	kfree(work);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) static void once_disable_jump(struct static_key_true *key)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) 	struct once_work *w;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) 	w = kmalloc(sizeof(*w), GFP_ATOMIC);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) 	if (!w)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) 		return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) 	INIT_WORK(&w->work, once_deferred);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) 	w->key = key;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) 	schedule_work(&w->work);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) static DEFINE_SPINLOCK(once_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) bool __do_once_start(bool *done, unsigned long *flags)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) 	__acquires(once_lock)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) 	spin_lock_irqsave(&once_lock, *flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) 	if (*done) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) 		spin_unlock_irqrestore(&once_lock, *flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) 		/* Keep sparse happy by restoring an even lock count on
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) 		 * this lock. In case we return here, we don't call into
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) 		 * __do_once_done but return early in the DO_ONCE() macro.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) 		 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) 		__acquire(once_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) 		return false;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) 	return true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53) EXPORT_SYMBOL(__do_once_start);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) void __do_once_done(bool *done, struct static_key_true *once_key,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) 		    unsigned long *flags)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57) 	__releases(once_lock)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59) 	*done = true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60) 	spin_unlock_irqrestore(&once_lock, *flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61) 	once_disable_jump(once_key);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63) EXPORT_SYMBOL(__do_once_done);