A common pattern in RCU code is to assign a new value to an RCU pointer after having read and stored the old value. Introduce a macro for this pattern.
Signed-off-by: Bart Van Assche <[email protected]> Acked-by: Paul E. McKenney <[email protected]> Cc: Christoph Hellwig <[email protected]> Cc: Hannes Reinecke <[email protected]> Cc: Johannes Thumshirn <[email protected]> Cc: Shane M Seymour <[email protected]> --- include/linux/rcupdate.h | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index f816fc72b51e..8e920f0ecb07 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -407,6 +407,22 @@ static inline void rcu_preempt_sleep_check(void) { } _r_a_p__v; \ }) +/** + * rcu_swap_protected() - swap an RCU and a regular pointer + * @rcu_ptr: RCU pointer + * @ptr: regular pointer + * @c: the conditions under which the dereference will take place + * + * Perform swap(@rcu_ptr, @ptr) where @rcu_ptr is an RCU-annotated pointer and + * @c is the argument that is passed to the rcu_dereference_protected() call + * used to read that pointer. + */ +#define rcu_swap_protected(rcu_ptr, ptr, c) do { \ + typeof(ptr) __tmp = rcu_dereference_protected((rcu_ptr), (c)); \ + rcu_assign_pointer((rcu_ptr), (ptr)); \ + (ptr) = __tmp; \ +} while (0) + /** * rcu_access_pointer() - fetch RCU pointer with no dereferencing * @p: The pointer to read -- 2.14.1
