Re: [PATCH] cast used->idx to volatile

[Linhaifeng <haifeng.lin-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>]

On 2015/3/21 16:07, linhaifeng wrote:
> From: Linhaifeng <haifeng.lin-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
> 
> Same as rte_vhost_enqueue_burst we should cast used->idx
> to volatile before notify guest.
> 
> Signed-off-by: Linhaifeng <haifeng.lin-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
> ---
>  lib/librte_vhost/vhost_rxtx.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/librte_vhost/vhost_rxtx.c b/lib/librte_vhost/vhost_rxtx.c
> index 535c7a1..8d674d1 100644
> --- a/lib/librte_vhost/vhost_rxtx.c
> +++ b/lib/librte_vhost/vhost_rxtx.c
> @@ -722,7 +722,7 @@ rte_vhost_dequeue_burst(struct virtio_net *dev, uint16_t queue_id,
>  	}
>  
>  	rte_compiler_barrier();
> -	vq->used->idx += entry_success;
> +	*(volatile uint16_t *)&vq->used->idx += entry_success;
>  	/* Kick guest if required. */
>  	if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT))
>  		eventfd_write((int)vq->callfd, 1);
> 

-- 
Regards,
Haifeng