[PATCH] block: Use RCU_INIT_POINTER(x, NULL) in blk-ioc.c

[PATCH] block: Use RCU_INIT_POINTER(x, NULL) in blk-ioc.c

[Monam Agarwal]

This patch replaces rcu_assign_pointer(x, NULL) with RCU_INIT_POINTER(x, NULL)

The rcu_assign_pointer() ensures that the initialization of a structure 
is carried out before storing a pointer to that structure. 
And in the case of the NULL pointer, there is no structure to initialize.
So, rcu_assign_pointer(p, NULL) can be safely converted to RCU_INIT_POINTER(p, NULL)

Signed-off-by: Monam Agarwal <monamagarwal123@gmail.com>
---
 block/blk-ioc.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/blk-ioc.c b/block/blk-ioc.c
index 242df01..6585186 100644
--- a/block/blk-ioc.c
+++ b/block/blk-ioc.c
@@ -69,7 +69,7 @@ static void ioc_destroy_icq(struct io_cq *icq)
 	 * will.  Hint assignment itself can race safely.
 	 */
 	if (rcu_dereference_raw(ioc->icq_hint) == icq)
-		rcu_assign_pointer(ioc->icq_hint, NULL);
+		RCU_INIT_POINTER(ioc->icq_hint, NULL);
 
 	ioc_exit_icq(icq);
 
-- 
1.7.9.5

Re: [PATCH] block: Use RCU_INIT_POINTER(x, NULL) in blk-ioc.c

[Jens Axboe]

On 2014-03-22 13:29, Monam Agarwal wrote:
> This patch replaces rcu_assign_pointer(x, NULL) with RCU_INIT_POINTER(x, NULL)
>
> The rcu_assign_pointer() ensures that the initialization of a structure
> is carried out before storing a pointer to that structure.
> And in the case of the NULL pointer, there is no structure to initialize.
> So, rcu_assign_pointer(p, NULL) can be safely converted to RCU_INIT_POINTER(p, NULL)

What's the point of further complicating the API for cases where we 
don't even really care about performance?

-- 
Jens Axboe