#ifndef __LINUX_RCU_ASSIGN_POINTER_H__
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#define __LINUX_RCU_ASSIGN_POINTER_H__
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#include <linux/compiler.h>
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#include <asm/barrier.h>
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/**
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* RCU_INITIALIZER() - statically initialize an RCU-protected global variable
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* @v: The value to statically initialize with.
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*/
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#define RCU_INITIALIZER(v) (typeof(*(v)) __force __rcu *)(v)
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/**
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* rcu_assign_pointer() - assign to RCU-protected pointer
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* @p: pointer to assign to
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* @v: value to assign (publish)
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*
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* Assigns the specified value to the specified RCU-protected
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* pointer, ensuring that any concurrent RCU readers will see
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* any prior initialization.
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*
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* Inserts memory barriers on architectures that require them
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* (which is most of them), and also prevents the compiler from
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* reordering the code that initializes the structure after the pointer
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* assignment. More importantly, this call documents which pointers
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* will be dereferenced by RCU read-side code.
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*
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* In some special cases, you may use RCU_INIT_POINTER() instead
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* of rcu_assign_pointer(). RCU_INIT_POINTER() is a bit faster due
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* to the fact that it does not constrain either the CPU or the compiler.
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* That said, using RCU_INIT_POINTER() when you should have used
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* rcu_assign_pointer() is a very bad thing that results in
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* impossible-to-diagnose memory corruption. So please be careful.
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* See the RCU_INIT_POINTER() comment header for details.
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*
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* Note that rcu_assign_pointer() evaluates each of its arguments only
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* once, appearances notwithstanding. One of the "extra" evaluations
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* is in typeof() and the other visible only to sparse (__CHECKER__),
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* neither of which actually execute the argument. As with most cpp
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* macros, this execute-arguments-only-once property is important, so
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* please be careful when making changes to rcu_assign_pointer() and the
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* other macros that it invokes.
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*/
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#define rcu_assign_pointer(p, v) \
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({ \
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uintptr_t _r_a_p__v = (uintptr_t)(v); \
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\
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if (__builtin_constant_p(v) && (_r_a_p__v) == (uintptr_t)NULL) \
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WRITE_ONCE((p), (typeof(p))(_r_a_p__v)); \
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else \
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smp_store_release(&p, RCU_INITIALIZER((typeof(p))_r_a_p__v)); \
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_r_a_p__v; \
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})
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#endif
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