[net-next,05/11] tuntap: tweak on the path of non-xdp case in tun_build_skb()
diff mbox series

Message ID 20180906040526.22518-6-jasowang@redhat.com
State New, archived
Headers show
Series
  • Vhost_net TX batching
Related show

Commit Message

Jason Wang Sept. 6, 2018, 4:05 a.m. UTC
If we're sure not to go native XDP, there's no need for several things
like bh and rcu stuffs.

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 drivers/net/tun.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

Comments

Michael S. Tsirkin Sept. 6, 2018, 5:16 p.m. UTC | #1
On Thu, Sep 06, 2018 at 12:05:20PM +0800, Jason Wang wrote:
> If we're sure not to go native XDP, there's no need for several things
> like bh and rcu stuffs.
> 
> Signed-off-by: Jason Wang <jasowang@redhat.com>

True...

> ---
>  drivers/net/tun.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index f8cdcfa392c3..389aa0727cc6 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -1675,10 +1675,12 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
>  	 * of xdp_prog above, this should be rare and for simplicity
>  	 * we do XDP on skb in case the headroom is not enough.
>  	 */
> -	if (hdr->gso_type || !xdp_prog)
> +	if (hdr->gso_type || !xdp_prog) {
>  		*skb_xdp = 1;
> -	else
> -		*skb_xdp = 0;
> +		goto build;
> +	}
> +
> +	*skb_xdp = 0;
>  
>  	local_bh_disable();
>  	rcu_read_lock();
> @@ -1724,6 +1726,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
>  	rcu_read_unlock();
>  	local_bh_enable();
>  
> +build:

But this is spaghetti code. Please just put common
code into functions and call them, don't goto.

>  	skb = build_skb(buf, buflen);
>  	if (!skb) {
>  		skb = ERR_PTR(-ENOMEM);
> -- 
> 2.17.1
Jason Wang Sept. 7, 2018, 3:24 a.m. UTC | #2
On 2018年09月07日 01:16, Michael S. Tsirkin wrote:
> On Thu, Sep 06, 2018 at 12:05:20PM +0800, Jason Wang wrote:
>> If we're sure not to go native XDP, there's no need for several things
>> like bh and rcu stuffs.
>>
>> Signed-off-by: Jason Wang <jasowang@redhat.com>
> True...
>
>> ---
>>   drivers/net/tun.c | 9 ++++++---
>>   1 file changed, 6 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
>> index f8cdcfa392c3..389aa0727cc6 100644
>> --- a/drivers/net/tun.c
>> +++ b/drivers/net/tun.c
>> @@ -1675,10 +1675,12 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
>>   	 * of xdp_prog above, this should be rare and for simplicity
>>   	 * we do XDP on skb in case the headroom is not enough.
>>   	 */
>> -	if (hdr->gso_type || !xdp_prog)
>> +	if (hdr->gso_type || !xdp_prog) {
>>   		*skb_xdp = 1;
>> -	else
>> -		*skb_xdp = 0;
>> +		goto build;
>> +	}
>> +
>> +	*skb_xdp = 0;
>>   
>>   	local_bh_disable();
>>   	rcu_read_lock();
>> @@ -1724,6 +1726,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
>>   	rcu_read_unlock();
>>   	local_bh_enable();
>>   
>> +build:
> But this is spaghetti code. Please just put common
> code into functions and call them, don't goto.

Ok, will do this.

Thanks

>
>>   	skb = build_skb(buf, buflen);
>>   	if (!skb) {
>>   		skb = ERR_PTR(-ENOMEM);
>> -- 
>> 2.17.1

Patch
diff mbox series

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index f8cdcfa392c3..389aa0727cc6 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1675,10 +1675,12 @@  static struct sk_buff *tun_build_skb(struct tun_struct *tun,
 	 * of xdp_prog above, this should be rare and for simplicity
 	 * we do XDP on skb in case the headroom is not enough.
 	 */
-	if (hdr->gso_type || !xdp_prog)
+	if (hdr->gso_type || !xdp_prog) {
 		*skb_xdp = 1;
-	else
-		*skb_xdp = 0;
+		goto build;
+	}
+
+	*skb_xdp = 0;
 
 	local_bh_disable();
 	rcu_read_lock();
@@ -1724,6 +1726,7 @@  static struct sk_buff *tun_build_skb(struct tun_struct *tun,
 	rcu_read_unlock();
 	local_bh_enable();
 
+build:
 	skb = build_skb(buf, buflen);
 	if (!skb) {
 		skb = ERR_PTR(-ENOMEM);