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-rw-r--r--include/linux/compiler.h21
1 files changed, 4 insertions, 17 deletions
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 793c0829e3a3..2e853b679a5d 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -304,23 +304,6 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s
__u.__val; \
})
-/**
- * smp_cond_acquire() - Spin wait for cond with ACQUIRE ordering
- * @cond: boolean expression to wait for
- *
- * Equivalent to using smp_load_acquire() on the condition variable but employs
- * the control dependency of the wait to reduce the barrier on many platforms.
- *
- * The control dependency provides a LOAD->STORE order, the additional RMB
- * provides LOAD->LOAD order, together they provide LOAD->{LOAD,STORE} order,
- * aka. ACQUIRE.
- */
-#define smp_cond_acquire(cond) do { \
- while (!(cond)) \
- cpu_relax(); \
- smp_rmb(); /* ctrl + rmb := acquire */ \
-} while (0)
-
#endif /* __KERNEL__ */
#endif /* __ASSEMBLY__ */
@@ -545,10 +528,14 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s
* Similar to rcu_dereference(), but for situations where the pointed-to
* object's lifetime is managed by something other than RCU. That
* "something other" might be reference counting or simple immortality.
+ *
+ * The seemingly unused void * variable is to validate @p is indeed a pointer
+ * type. All pointer types silently cast to void *.
*/
#define lockless_dereference(p) \
({ \
typeof(p) _________p1 = READ_ONCE(p); \
+ __maybe_unused const void * const _________p2 = _________p1; \
smp_read_barrier_depends(); /* Dependency order vs. p above. */ \
(_________p1); \
})