diff options
Diffstat (limited to 'include/linux/atomic.h')
| -rw-r--r-- | include/linux/atomic.h | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/include/linux/atomic.h b/include/linux/atomic.h index ae3f30923d05..b89ba36cab94 100644 --- a/include/linux/atomic.h +++ b/include/linux/atomic.h @@ -522,6 +522,29 @@ #endif /* xchg_relaxed */ /** + * atomic_fetch_add_unless - add unless the number is already a given value + * @v: pointer of type atomic_t + * @a: the amount to add to v... + * @u: ...unless v is equal to u. + * + * Atomically adds @a to @v, if @v was not already @u. + * Returns the original value of @v. + */ +#ifndef atomic_fetch_add_unless +static inline int atomic_fetch_add_unless(atomic_t *v, int a, int u) +{ + int c = atomic_read(v); + + do { + if (unlikely(c == u)) + break; + } while (!atomic_try_cmpxchg(v, &c, c + a)); + + return c; +} +#endif + +/** * atomic_add_unless - add unless the number is already a given value * @v: pointer of type atomic_t * @a: the amount to add to v... |