linux-kernel - Re: [PATCH net-next] tuntap: hardware vlan tx support

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Message-ID: <51EF47BC.4090107@redhat.com>
Date:	Wed, 24 Jul 2013 11:19:24 +0800
From:	Jason Wang <jasowang@...hat.com>
To:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
CC:	davem@...emloft.net, mst@...hat.com, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, Basil Gor <basil.gor@...il.com>
Subject: Re: [PATCH net-next] tuntap: hardware vlan tx support

On 07/23/2013 08:12 PM, Sergei Shtylyov wrote:
> Hello.
>
> On 23-07-2013 11:15, Jason Wang wrote:
>
>> Inspired by commit f09e2249c4f5c7c13261ec73f5a7807076af0c8e (macvtap:
>> restore
>> vlan header on user read). This patch adds hardware vlan tx support for
>> tuntap. This is done by copying vlan header directly into userspace in
>> tun_put_user() instead of doing it through __vlan_put_tag() in
>> dev_hard_start_xmit(). This eliminates one unnecessary memove in
>
>    s/memove/memmove/?
>

Yes.
>> vlan_insert_tag() for 802.1ad and 802.1q traffic.
>
>> pktgen test shows about 20% improvement for 802.1q traffic:
>
>> Before:
>>    662149pps 317Mb/sec (317831520bps) errors: 0
>> After:
>>    801033pps 384Mb/sec (384495840bps) errors: 0
>
>> Cc: Basil Gor <basil.gor@...il.com>
>> Cc: Michael S. Tsirkin <mst@...hat.com>
>> Signed-off-by: Jason Wang <jasowang@...hat.com>
>> ---
>>   drivers/net/tun.c |   39 +++++++++++++++++++++++++++++++++++----
>>   1 files changed, 35 insertions(+), 4 deletions(-)
>
>> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
>> index a72d141..66e265d 100644
>> --- a/drivers/net/tun.c
>> +++ b/drivers/net/tun.c
> [...]
>> @@ -1328,11 +1330,39 @@ static ssize_t tun_put_user(struct tun_struct
>> *tun,
>>           total += tun->vnet_hdr_sz;
>>       }
>>
>> -    len = min_t(int, skb->len, len);
>> +    if (!vlan_tx_tag_present(skb))
>> +        len = min_t(int, skb->len, len);
>> +    else {
>
>    According to Documentation/CodingStyle chapter 3, both arms of an
> *if* statement should have {} if one arm has it.
>

Right.
>> +        int copy, ret;
>> +        struct {
>> +            __be16 h_vlan_proto;
>> +            __be16 h_vlan_TCI;
>> +        } veth;
>
>    Empty line wouldn't hurt here, after declarations...
>

Ok
>> +        veth.h_vlan_proto = skb->vlan_proto;
>> +        veth.h_vlan_TCI = htons(vlan_tx_tag_get(skb));
> [...]
>
> WBR, Sergei
>

Thanks, will correct them.
> -- 
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