| #include <linux/export.h> |
| #include <linux/spinlock.h> |
| #include <linux/atomic.h> |
| * This is an implementation of the notion of "decrement a |
| * reference count, and return locked if it decremented to zero". |
| * NOTE NOTE NOTE! This is _not_ equivalent to |
| * if (atomic_dec_and_test(&atomic)) { |
| * because the spin-lock and the decrement must be |
| int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock) |
| /* Subtract 1 from counter unless that drops it to 0 (ie. it was 1) */ |
| if (atomic_add_unless(atomic, -1, 1)) |
| /* Otherwise do it the slow way */ |
| if (atomic_dec_and_test(atomic)) |
| EXPORT_SYMBOL(_atomic_dec_and_lock); |