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git.proxmox.com Git - mirror_ubuntu-jammy-kernel.git/blob - lib/dec_and_lock.c
1 #include <linux/module.h>
2 #include <linux/spinlock.h>
3 #include <asm/atomic.h>
6 * This is an implementation of the notion of "decrement a
7 * reference count, and return locked if it decremented to zero".
9 * NOTE NOTE NOTE! This is _not_ equivalent to
11 * if (atomic_dec_and_test(&atomic)) {
17 * because the spin-lock and the decrement must be
20 int _atomic_dec_and_lock(atomic_t
*atomic
, spinlock_t
*lock
)
23 /* Subtract 1 from counter unless that drops it to 0 (ie. it was 1) */
24 if (atomic_add_unless(atomic
, -1, 1))
27 /* Otherwise do it the slow way */
29 if (atomic_dec_and_test(atomic
))
35 EXPORT_SYMBOL(_atomic_dec_and_lock
);