diff options
Diffstat (limited to 'scripts/atomic/fallbacks/fetch_add_unless')
| -rw-r--r-- | scripts/atomic/fallbacks/fetch_add_unless | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/scripts/atomic/fallbacks/fetch_add_unless b/scripts/atomic/fallbacks/fetch_add_unless new file mode 100644 index 000000000000..d2c091db7eae --- /dev/null +++ b/scripts/atomic/fallbacks/fetch_add_unless @@ -0,0 +1,23 @@ +cat << EOF +/** + * ${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, so long as @v was not already @u. + * Returns original value of @v + */ +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; +} +EOF |