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From:   Menglong Dong <menglong8.dong@gmail.com>
Date:   Sat, 5 Jun 2021 09:28:44 +0800
Message-ID: <CADxym3ZostCAY0GwUpTxEHcOPyOj5Lmv4F7xP-Q4=AEAVaEAxw@mail.gmail.com>
Subject: Re: [PATCH net-next] net: tipc: fix FB_MTU eat two pages
To:     Jon Maloy <jmaloy@redhat.com>
Cc:     ying.xue@windriver.com, David Miller <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        netdev <netdev@vger.kernel.org>,
        tipc-discussion@lists.sourceforge.net,
        Menglong Dong <dong.menglong@zte.com.cn>,
        Zeal Robot <zealci@zte.com.cn>
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Hello Maloy,

On Sat, Jun 5, 2021 at 3:20 AM Jon Maloy <jmaloy@redhat.com> wrote:
>
>
[...]
> Please don't add any extra file just for this little fix. We have enough
> files.
> Keep the macros in msg.h/c where they used to be.  You can still add
> your copyright line to those files.
> Regarding the macros kept inside msg.c, they are there because we design
> by the principle of minimal exposure, even among our module internal files.
> Otherwise it is ok.
>

I don't want to add a new file too, but I found it's hard to define FB_MTU. I
tried to define it in msg.h, and 'crypto.h' should be included, which
'BUF_HEADROOM' is defined in. However, 'msg.h' is already included in
'crypto.h', so it doesn't work.

I tried to define FB_MTU in 'crypto.h', but it feels weird to define
it here. And
FB_MTU is also used in 'bcast.c', so it can't be defined in 'msg.c'.

I will see if there is a better solution.

Thanks!
Menglong Dong

> > @@ -0,0 +1,55 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only */
> > +/*
> > + * Copyright 2021 ZTE Corporation.
> > + * All rights reserved.
> > + *
> > + * Redistribution and use in source and binary forms, with or without
> > + * modification, are permitted provided that the following conditions are met:
> > + *
> > + * 1. Redistributions of source code must retain the above copyright
> > + *    notice, this list of conditions and the following disclaimer.
> > + * 2. Redistributions in binary form must reproduce the above copyright
> > + *    notice, this list of conditions and the following disclaimer in the
> > + *    documentation and/or other materials provided with the distribution.
> > + * 3. Neither the names of the copyright holders nor the names of its
> > + *    contributors may be used to endorse or promote products derived from
> > + *    this software without specific prior written permission.
> > + *
> > + * Alternatively, this software may be distributed under the terms of the
> > + * GNU General Public License ("GPL") version 2 as published by the Free
> > + * Software Foundation.
> > + *
> > + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
> > + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> > + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
> > + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
> > + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
> > + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
> > + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
> > + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
> > + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
> > + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
> > + * POSSIBILITY OF SUCH DAMAGE.
> > + */
> > +
> > +#ifndef _TIPC_MTU_H
> > +#define _TIPC_MTU_H
> > +
> > +#include <linux/tipc.h>
> > +#include "crypto.h"
> > +
> > +#ifdef CONFIG_TIPC_CRYPTO
> > +#define BUF_HEADROOM ALIGN(((LL_MAX_HEADER + 48) + EHDR_MAX_SIZE), 16)
> > +#define BUF_TAILROOM (TIPC_AES_GCM_TAG_SIZE)
> > +#define FB_MTU       (PAGE_SIZE - \
> > +              SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) - \
> > +              SKB_DATA_ALIGN(BUF_HEADROOM + BUF_TAILROOM + 3))
> > +#else
> > +#define BUF_HEADROOM (LL_MAX_HEADER + 48)
> > +#define BUF_TAILROOM 16
> > +#define FB_MTU       (PAGE_SIZE - \
> > +              SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) - \
> > +              SKB_DATA_ALIGN(BUF_HEADROOM + 3))
> > +#endif
> > +
> > +#endif
>