On 12/12/2018 01:58 AM, Xiaozhou Liu wrote:
> Use RCU_INIT_POINTER() instead of rcu_assign_pointer() to
> NULL out the pointer because it is a bit faster.
>
> Signed-off-by: Xiaozhou Liu <liuxiaoz...@bytedance.com>
> ---
> net/core/sock_reuseport.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/core/sock_reuseport.c b/net/core/sock_reuseport.c
> index d8fe3e549373..25e71355f0a6 100644
> --- a/net/core/sock_reuseport.c
> +++ b/net/core/sock_reuseport.c
> @@ -205,7 +205,7 @@ void reuseport_detach_sock(struct sock *sk)
> if (reuse->reuseport_id)
> bpf_sk_reuseport_detach(sk);
>
> - rcu_assign_pointer(sk->sk_reuseport_cb, NULL);
> + RCU_INIT_POINTER(sk->sk_reuseport_cb, NULL);
>
> for (i = 0; i < reuse->num_socks; i++) {
> if (reuse->socks[i] == sk) {
>
It is _not_ faster.
Just different ways to do the exact same thing.
For some reason you missed this two years old commit :
commit 3a37f7275cda5ad25c1fe9be8f20c76c60d175fa
Author: Paul E. McKenney <paul...@linux.vnet.ibm.com>
Date: Sun May 1 18:46:54 2016 -0700
rcu: No ordering for rcu_assign_pointer() of NULL
This commit does a compile-time check for rcu_assign_pointer() of NULL,
and uses WRITE_ONCE() rather than smp_store_release() in that case.
Reported-by: Christoph Hellwig <h...@infradead.org>
Signed-off-by: Paul E. McKenney <paul...@linux.vnet.ibm.com>
