linux-kernel - Re: [PATCH net-next 1/6] net: mvpp2: only free the TSO header buffers when it was allocated

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Message-ID: <20171208082410.GB4359@kwain>
Date:   Fri, 8 Dec 2017 09:24:10 +0100
From:   Antoine Tenart <antoine.tenart@...e-electrons.com>
To:     David Miller <davem@...emloft.net>
Cc:     antoine.tenart@...e-electrons.com,
        gregory.clement@...e-electrons.com,
        thomas.petazzoni@...e-electrons.com,
        miquel.raynal@...e-electrons.com, nadavh@...vell.com,
        mw@...ihalf.com, stefanc@...vell.com, ymarkman@...vell.com,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next 1/6] net: mvpp2: only free the TSO header
 buffers when it was allocated

Hi David,

On Thu, Dec 07, 2017 at 02:53:29PM -0500, David Miller wrote:
> From: Antoine Tenart <antoine.tenart@...e-electrons.com>
> Date: Thu,  7 Dec 2017 09:48:58 +0100
> 
> > This patch adds a check to only free the TSO header buffer when its
> > allocation previously succeeded.
> > 
> > Signed-off-by: Antoine Tenart <antoine.tenart@...e-electrons.com>
> 
> No, please keep this as a failure to bring up.
> 
> Even if you emit a log message, it is completely unintuitive to
> have netdev features change on the user just because of a memory
> allocation failure.

OK, makes sense.

One other possibility would be to disable TSO if CMA_SIZE_MBYTES is set
to a too small value (i.e. its default). But I don't think this would be
a good solution either.

The drawback is the default configuration when selecting DMA_CMA won't
work for PPv2.

Anyway, I'll send a v2 without these patches.

Thanks!
Antoine

-- 
Antoine Ténart, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com