Re: [PATCH] macvtap: use set_curren_state to ensure mb

[Eric Dumazet <eric.dumazet@gmail.com>]

On Tue, 2012-06-05 at 18:46 +0800, Hong zhi guo wrote:
> replace raw assignment of current->state with
> set_current_state(TASK_...) to ensure memory barrier.
> 
> Signed-off-by: Hong Zhiguo <honkiko@gmail.com>
> ---
>  drivers/net/macvtap.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
> index 2ee56de..62754f6 100644
> --- a/drivers/net/macvtap.c
> +++ b/drivers/net/macvtap.c
> @@ -853,7 +853,7 @@ static ssize_t macvtap_do_read(struct
> macvtap_queue *q, struct kiocb *iocb,
> 
>  	add_wait_queue(sk_sleep(&q->sk), &wait);
>  	while (len) {
> -		current->state = TASK_INTERRUPTIBLE;
> +		set_current_state(TASK_INTERRUPTIBLE);
> 
>  		/* Read frames from the queue */
>  		skb = skb_dequeue(&q->sk.sk_receive_queue);
> @@ -875,7 +875,7 @@ static ssize_t macvtap_do_read(struct
> macvtap_queue *q, struct kiocb *iocb,
>  		break;
>  	}
> 
> -	current->state = TASK_RUNNING;
> +	set_current_state(TASK_RUNNING);
>  	remove_wait_queue(sk_sleep(&q->sk), &wait);
>  	return ret;
>  }


Why not using the more standard :

prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);

and

finish_wait(sk_sleep(sk), &wait);