The unconditional guard destructors check whether the lock pointer is NULL before unlocking. This check is dead code because unconditional guards guarantee a non-NULL lock pointer at destructor time. DEFINE_GUARD() and DEFINE_LOCK_GUARD_1() both run the lock operation in the constructor before returning. If the pointer were NULL, the lock operation (e.g. mutex_lock(NULL)) would crash before the constructor returns. The destructor never runs with a NULL pointer. DEFINE_LOCK_GUARD_0() hardcodes .lock = (void *)1 in the constructor, so it is never NULL by construction. Conditional (_try) variants: DEFINE_GUARD_COND() and DEFINE_LOCK_GUARD_1_COND() use EXTEND_CLASS_COND(), whose wrapper destructor returns early when the lock was not acquired, before reaching the base destructor since 2deccd5c862a ("cleanup: Optimize guards"): if (_cond) return; class_##_name##_destructor(_T); As compiled by GCC-11 with defconfig on top of the locking/core: Total: Before=23889980, After=23833993, chg -0.23% Signed-off-by: Dmitry Ilvokhin --- Changes in v2: - Expand commit message with detailed reasoning, why the proposed change is correct. - Rebase on top of locking/core. v1: https://lore.kernel.org/all/20260427165037.205337-1-d@ilvokhin.com/ See also [1] for relevant discussion. [1]: https://lore.kernel.org/all/afCS4d4YccQFtvpi@shell.ilvokhin.com/ include/linux/cleanup.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/include/linux/cleanup.h b/include/linux/cleanup.h index ea95ca4bc11c..1410effa8780 100644 --- a/include/linux/cleanup.h +++ b/include/linux/cleanup.h @@ -397,7 +397,7 @@ static __maybe_unused const bool class_##_name##_is_conditional = _is_cond __DEFINE_GUARD_LOCK_PTR(_name, _T) #define DEFINE_GUARD(_name, _type, _lock, _unlock) \ - DEFINE_CLASS(_name, _type, if (_T) { _unlock; }, ({ _lock; _T; }), _type _T); \ + DEFINE_CLASS(_name, _type, _unlock, ({ _lock; _T; }), _type _T); \ DEFINE_CLASS_IS_GUARD(_name) #define DEFINE_GUARD_COND_4(_name, _ext, _lock, _cond) \ @@ -491,7 +491,7 @@ typedef struct { \ static __always_inline void class_##_name##_destructor(class_##_name##_t *_T) \ __no_context_analysis \ { \ - if (_T->lock) { _unlock; } \ + _unlock; \ } \ \ __DEFINE_GUARD_LOCK_PTR(_name, &_T->lock) -- 2.53.0-Meta