linux-kernel - Re: [PATCH net-next 03/11] tuntap: enable bh early during processing XDP

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Date:   Thu, 6 Sep 2018 13:02:51 -0400
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Jason Wang <jasowang@...hat.com>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH net-next 03/11] tuntap: enable bh early during processing
 XDP

On Thu, Sep 06, 2018 at 12:05:18PM +0800, Jason Wang wrote:
> This patch move the bh enabling a little bit earlier, this will be
> used for factoring out the core XDP logic of tuntap.
> 
> Signed-off-by: Jason Wang <jasowang@...hat.com>

Acked-by: Michael S. Tsirkin <mst@...hat.com>

no reason to disable bh for non-xdp things.

> ---
>  drivers/net/tun.c | 10 +++-------
>  1 file changed, 3 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index d3677a544b56..372caf7d67d9 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -1726,22 +1726,18 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
>  			goto err_xdp;
>  		}
>  	}
> +	rcu_read_unlock();
> +	local_bh_enable();
>  
>  	skb = build_skb(buf, buflen);
> -	if (!skb) {
> -		rcu_read_unlock();
> -		local_bh_enable();
> +	if (!skb)
>  		return ERR_PTR(-ENOMEM);
> -	}
>  
>  	skb_reserve(skb, pad - delta);
>  	skb_put(skb, len);
>  	get_page(alloc_frag->page);
>  	alloc_frag->offset += buflen;
>  
> -	rcu_read_unlock();
> -	local_bh_enable();
> -
>  	return skb;
>  
>  err_redirect:
> -- 
> 2.17.1