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From: Xie He <xie.he.0141@gmail.com>
To: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Linux Kernel Network Developers <netdev@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Linux X25 <linux-x25@vger.kernel.org>,
	Brian Norris <briannorris@chromium.org>
Subject: Re: [PATCH v2] drivers/net/wan/lapbether: Use needed_headroom instead of hard_header_len
Date: Sat, 1 Aug 2020 17:58:30 -0700	[thread overview]
Message-ID: <CAJht_EOdrnuYn0COTW-6kEivbq+1FqzNnWgs8E_xsdyD_pwomA@mail.gmail.com> (raw)
In-Reply-To: <CA+FuTSdJ1c0R2qmKtm9vWpKnMv=-B0yAaronGkqg=jYZBfqceA@mail.gmail.com>

On Sat, Aug 1, 2020 at 6:31 AM Willem de Bruijn
<willemdebruijn.kernel@gmail.com> wrote:
>
> The kernel interface cannot be changed. If packet sockets used to pass
> the first byte up to userspace, they have to continue to do so.
>
> So I think you can limit the header_ops to only dev_hard_header.

Actually if we want to keep the kernel interface unchanged, we
shouldn't implement header_ops for dev_hard_header either, because
this changes the way the user space program sends DGRAM packets, too.
Before the change the userspace program needs to add the 1-byte header
before sending, and after the change the userspace program will let
the kernel add the header via dev_hard_header.

> Fixes should be small and targeted. Any larger refactoring is
> best addressed in a separate net-next patch.

I guess the best way for this fix patch would be just add a 0-byte
packet check before the driver reads skb->data[0].

Thanks! I'll add the check and re-send the patch.

  reply	other threads:[~2020-08-02  0:58 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-30  7:37 [PATCH v2] drivers/net/wan/lapbether: Use needed_headroom instead of hard_header_len Xie He
2020-07-30  8:02 ` Xie He
2020-08-04  6:53   ` Martin Schiller
2020-08-04  7:05     ` Willem de Bruijn
2020-08-04 10:07       ` Xie He
2020-08-04 10:13         ` Xie He
2020-08-04  9:48     ` Xie He
2020-07-31  1:36 ` Xie He
2020-07-31 14:12   ` Willem de Bruijn
2020-07-31 20:40     ` Xie He
2020-08-01  2:33       ` Willem de Bruijn
2020-08-01 12:45         ` Xie He
2020-08-01 13:30           ` Willem de Bruijn
2020-08-02  0:58             ` Xie He [this message]
2020-07-31  1:57 ` Xie He

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