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/export.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/atomic.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  5) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  6) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  7)  * This is an implementation of the notion of "decrement a
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  8)  * reference count, and return locked if it decremented to zero".
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  9)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10)  * NOTE NOTE NOTE! This is _not_ equivalent to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12)  *	if (atomic_dec_and_test(&atomic)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13)  *		spin_lock(&lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14)  *		return 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15)  *	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16)  *	return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18)  * because the spin-lock and the decrement must be
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19)  * "atomic".
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) 	/* Subtract 1 from counter unless that drops it to 0 (ie. it was 1) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) 	if (atomic_add_unless(atomic, -1, 1))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) 		return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) 	/* Otherwise do it the slow way */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) 	spin_lock(lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) 	if (atomic_dec_and_test(atomic))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) 		return 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) 	spin_unlock(lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) 	return 0;
^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) EXPORT_SYMBOL(_atomic_dec_and_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) int _atomic_dec_and_lock_irqsave(atomic_t *atomic, spinlock_t *lock,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) 				 unsigned long *flags)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) 	/* Subtract 1 from counter unless that drops it to 0 (ie. it was 1) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) 	if (atomic_add_unless(atomic, -1, 1))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) 		return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) 	/* Otherwise do it the slow way */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) 	spin_lock_irqsave(lock, *flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) 	if (atomic_dec_and_test(atomic))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) 		return 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) 	spin_unlock_irqrestore(lock, *flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) 	return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) EXPORT_SYMBOL(_atomic_dec_and_lock_irqsave);