netdev - Re: [PATCH v3 net-next] l2tp: Refactor the codes with existing macros instead of literal number

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Message-ID: <CA+6hz4rSg6DSMHNJtrD=GFno08Sj0jb8ezktY-=yH3k5zTVZMQ@mail.gmail.com>
Date:   Mon, 22 Aug 2016 08:13:48 +0800
From:   Feng Gao <gfree.wind@...il.com>
To:     Philp Prindeville <philipp@...fish-solutions.com>
Cc:     Gao Feng <fgao@...vckh6395k16k5.yundunddos.com>, paulus@...ba.org,
        "David S. Miller" <davem@...emloft.net>,
        Guillaume Nault <g.nault@...halink.fr>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: [PATCH v3 net-next] l2tp: Refactor the codes with existing macros
 instead of literal number

inline

On Mon, Aug 22, 2016 at 6:36 AM, Philp Prindeville
<philipp@...fish-solutions.com> wrote:
> Inline
>
>
> On 08/20/2016 09:52 AM, fgao@...vckh6395k16k5.yundunddos.com wrote:
>>
>> From: Gao Feng <fgao@...ai8.com>
>>
>> Use PPP_ALLSTATIONS, PPP_UI, and SEND_SHUTDOWN instead of 0xff,
>> 0x03, and 2 separately.
>>
>> Signed-off-by: Gao Feng <fgao@...ai8.com>
>> ---
>>   v3: Modify the subject;
>>   v2: Only replace the literal number with macros according to Guillaume's
>> advice
>>   v1: Inital patch
>>
>>   net/l2tp/l2tp_ppp.c | 8 ++++----
>>   1 file changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
>> index d9560aa..65e2fd6 100644
>> --- a/net/l2tp/l2tp_ppp.c
>> +++ b/net/l2tp/l2tp_ppp.c
>> @@ -177,7 +177,7 @@ static int pppol2tp_recv_payload_hook(struct sk_buff
>> *skb)
>>         if (!pskb_may_pull(skb, 2))
>>                 return 1;
>>   -     if ((skb->data[0] == 0xff) && (skb->data[1] == 0x03))
>> +       if ((skb->data[0] == PPP_ALLSTATIONS) && (skb->data[1] == PPP_UI))
>
>
> This should have used PPP_ADDRESS() and PPP_CONTROL() here.

In my initial patch, I replace them with PPP_ADDRESS() and PPP_CONTROL.
But Guillaume thought it was not clear as before.
So I revert it.

>
>>                 skb_pull(skb, 2);
>
>
> This magic number should go away.

Same as above.

>
>>         return 0;
>> @@ -282,7 +282,7 @@ static void pppol2tp_session_sock_put(struct
>> l2tp_session *session)
>>   static int pppol2tp_sendmsg(struct socket *sock, struct msghdr *m,
>>                             size_t total_len)
>>   {
>> -       static const unsigned char ppph[2] = { 0xff, 0x03 };
>> +       static const unsigned char ppph[2] = {PPP_ALLSTATIONS, PPP_UI};
>
>
> PPP has a 4-byte header.  Where's the protocol value?

In the original code, I fail to find the code which is used to fill
the protocol value.
So I keep the two bytes header. And I thought the protocol value may be filled
by the upper layer.

>
>>         struct sock *sk = sock->sk;
>>         struct sk_buff *skb;
>>         int error;
>> @@ -369,7 +369,7 @@ error:
>>    */
>>   static int pppol2tp_xmit(struct ppp_channel *chan, struct sk_buff *skb)
>>   {
>> -       static const u8 ppph[2] = { 0xff, 0x03 };
>> +       static const u8 ppph[2] = {PPP_ALLSTATIONS, PPP_UI};
>
>
> Same as above.
>
>
>
>>         struct sock *sk = (struct sock *) chan->private;
>>         struct sock *sk_tun;
>>         struct l2tp_session *session;
>> @@ -440,7 +440,7 @@ static void pppol2tp_session_close(struct l2tp_session
>> *session)
>>         BUG_ON(session->magic != L2TP_SESSION_MAGIC);
>>         if (sock) {
>> -               inet_shutdown(sock, 2);
>> +               inet_shutdown(sock, SEND_SHUTDOWN);
>>                 /* Don't let the session go away before our socket does */
>>                 l2tp_session_inc_refcount(session);
>>         }
>
>