Introduce functions to increase refcount but with a top limit above which they will fail to increase (the limit is inclusive). Setting the limit to INT_MAX indicates no limit. Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx> --- Changes since v9 [1]: - Change refcount limit to be used with xxx_acquire functions [1] https://lore.kernel.org/all/20250111042604.3230628-11-surenb@xxxxxxxxxx/ include/linux/refcount.h | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) diff --git a/include/linux/refcount.h b/include/linux/refcount.h index 4589d2e7bfea..80dc023ac2bf 100644 --- a/include/linux/refcount.h +++ b/include/linux/refcount.h @@ -213,13 +213,20 @@ static inline __must_check bool refcount_add_not_zero(int i, refcount_t *r) } static inline __must_check __signed_wrap -bool __refcount_add_not_zero_acquire(int i, refcount_t *r, int *oldp) +bool __refcount_add_not_zero_limited_acquire(int i, refcount_t *r, int *oldp, + int limit) { int old = refcount_read(r); do { if (!old) break; + + if (i > limit - old) { + if (oldp) + *oldp = old; + return false; + } } while (!atomic_try_cmpxchg_acquire(&r->refs, &old, old + i)); if (oldp) @@ -231,6 +238,18 @@ bool __refcount_add_not_zero_acquire(int i, refcount_t *r, int *oldp) return old; } +static inline __must_check bool +__refcount_inc_not_zero_limited_acquire(refcount_t *r, int *oldp, int limit) +{ + return __refcount_add_not_zero_limited_acquire(1, r, oldp, limit); +} + +static inline __must_check __signed_wrap +bool __refcount_add_not_zero_acquire(int i, refcount_t *r, int *oldp) +{ + return __refcount_add_not_zero_limited_acquire(i, r, oldp, INT_MAX); +} + /** * refcount_add_not_zero_acquire - add a value to a refcount with acquire ordering unless it is 0 * -- 2.48.1.601.g30ceb7b040-goog
