#ifndef __LINUX_RCUPDATE_H
#define __LINUX_RCUPDATE_H
-#ifdef __KERNEL__
-
#include <linux/cache.h>
#include <linux/spinlock.h>
#include <linux/threads.h>
*/
#define rcu_read_unlock_bh() __rcu_read_unlock_bh()
-/*
- * Prevent the compiler from merging or refetching accesses. The compiler
- * is also forbidden from reordering successive instances of ACCESS_ONCE(),
- * but only when the compiler is aware of some particular ordering. One way
- * to make the compiler aware of ordering is to put the two invocations of
- * ACCESS_ONCE() in different C statements.
- *
- * This macro does absolutely -nothing- to prevent the CPU from reordering,
- * merging, or refetching absolutely anything at any time.
- */
-#define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
-
/**
* rcu_dereference - fetch an RCU-protected pointer in an
* RCU read-side critical section. This pointer may later
* code.
*/
-#define rcu_assign_pointer(p, v) ({ \
- smp_wmb(); \
- (p) = (v); \
- })
+#define rcu_assign_pointer(p, v) \
+ ({ \
+ if (!__builtin_constant_p(v) || \
+ ((v) != NULL)) \
+ smp_wmb(); \
+ (p) = (v); \
+ })
/**
* synchronize_sched - block until all CPUs have exited any non-preemptive
extern void rcu_init(void);
extern int rcu_needs_cpu(int cpu);
-#endif /* __KERNEL__ */
#endif /* __LINUX_RCUPDATE_H */