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[209.85.217.42]) by smtp.gmail.com with ESMTPSA id y6sm3435056vke.35.2020.08.09.01.48.44 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 09 Aug 2020 01:48:45 -0700 (PDT) Received: by mail-vs1-f42.google.com with SMTP id a1so2821323vsp.4 for ; Sun, 09 Aug 2020 01:48:44 -0700 (PDT) X-Received: by 2002:a67:fdc4:: with SMTP id l4mr16028144vsq.51.1596962924152; Sun, 09 Aug 2020 01:48:44 -0700 (PDT) MIME-Version: 1.0 References: <20200808175251.582781-1-xie.he.0141@gmail.com> In-Reply-To: <20200808175251.582781-1-xie.he.0141@gmail.com> From: Willem de Bruijn Date: Sun, 9 Aug 2020 10:48:07 +0200 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH net] drivers/net/wan/lapbether: Added needed_tailroom To: Xie He Cc: "David S. Miller" , Jakub Kicinski , Network Development , linux-kernel , Linux X25 , Willem de Bruijn , Martin Schiller Content-Type: text/plain; charset="UTF-8" Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Sat, Aug 8, 2020 at 7:53 PM Xie He wrote: > > The underlying Ethernet device may request necessary tailroom to be > allocated by setting needed_tailroom. This driver should also set > needed_tailroom to request the tailroom needed by the underlying > Ethernet device to be allocated. > > Cc: Willem de Bruijn > Cc: Martin Schiller > Signed-off-by: Xie He > --- > drivers/net/wan/lapbether.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/net/wan/lapbether.c b/drivers/net/wan/lapbether.c > index 1ea15f2123ed..cc297ea9c6ec 100644 > --- a/drivers/net/wan/lapbether.c > +++ b/drivers/net/wan/lapbether.c > @@ -340,6 +340,7 @@ static int lapbeth_new_device(struct net_device *dev) > */ > ndev->needed_headroom = -1 + 3 + 2 + dev->hard_header_len > + dev->needed_headroom; > + ndev->needed_tailroom = dev->needed_tailroom; Does this solve an actual observed bug? In many ways lapbeth is similar to tunnel devices. This is not common.