From: Leon Romanovsky <leon@kernel.org>
To: Xie He <xie.he.0141@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Linux X25 <linux-x25@vger.kernel.org>,
Linux Kernel Network Developers <netdev@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Martin Schiller <ms@dev.tdt.de>, Krzysztof Halasa <khc@pm.waw.pl>
Subject: Re: [PATCH net-next RFC v3] net: hdlc_x25: Queue outgoing LAPB frames
Date: Mon, 15 Feb 2021 20:54:40 +0200 [thread overview]
Message-ID: <YCrDcMYgSgdKp4eX@unreal> (raw)
In-Reply-To: <CAJht_EOQBDdwa0keS9XTKZgXE44_b5cHJt=fFaKy-wFDpe6iaw@mail.gmail.com>
On Mon, Feb 15, 2021 at 09:23:32AM -0800, Xie He wrote:
> On Mon, Feb 15, 2021 at 1:25 AM Leon Romanovsky <leon@kernel.org> wrote:
> >
> > > + /* When transmitting data:
> > > + * first we'll remove a pseudo header of 1 byte,
> > > + * then the LAPB module will prepend an LAPB header of at most 3 bytes.
> > > + */
> > > + dev->needed_headroom = 3 - 1;
> >
> > 3 - 1 = 2
> >
> > Thanks
>
> Actually this is intentional. It makes the numbers more meaningful.
>
> The compiler should automatically generate the "2" so there would be
> no runtime penalty.
If you want it intentional, write it in the comment.
/* When transmitting data, we will need extra 2 bytes headroom,
* which are 3 bytes of LAPB header minus one byte of pseudo header.
*/
dev->needed_headroom = 2;
next prev parent reply other threads:[~2021-02-15 18:55 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-15 7:27 [PATCH net-next RFC v3] net: hdlc_x25: Queue outgoing LAPB frames Xie He
2021-02-15 9:24 ` Leon Romanovsky
2021-02-15 17:23 ` Xie He
2021-02-15 18:54 ` Leon Romanovsky [this message]
2021-02-15 19:08 ` Xie He
2021-02-16 6:03 ` Leon Romanovsky
2021-02-16 7:30 ` Xie He
2021-02-16 7:39 ` Leon Romanovsky
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