netdev - Re: [PATCH net] net: mvpp2: fix mvpp2 debugfs leak

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Message-ID: <CAPv3WKeCecHxmQS47eqZzSxaeLcu7P9CZ4GPeyEXQucggJ2Xig@mail.gmail.com>
Date:   Mon, 3 Oct 2022 20:46:51 +0200
From:   Marcin Wojtas <mw@...ihalf.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     "Russell King (Oracle)" <rmk+kernel@...linux.org.uk>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Sasha Levin <sashal@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Maxime Chevallier <maxime.chevallier@...tlin.com>,
        netdev@...r.kernel.org
Subject: Re: [PATCH net] net: mvpp2: fix mvpp2 debugfs leak

pon., 3 paź 2022 o 18:22 Greg Kroah-Hartman
<gregkh@...uxfoundation.org> napisał(a):
>
> On Mon, Oct 03, 2022 at 05:19:27PM +0100, Russell King (Oracle) wrote:
> > When mvpp2 is unloaded, the driver specific debugfs directory is not
> > removed, which technically leads to a memory leak. However, this
> > directory is only created when the first device is probed, so the
> > hardware is present. Removing the module is only something a developer
> > would to when e.g. testing out changes, so the module would be
> > reloaded. So this memory leak is minor.
> >
> > The original attempt in commit fe2c9c61f668 ("net: mvpp2: debugfs: fix
> > memory leak when using debugfs_lookup()") that was labelled as a memory
> > leak fix was not, it fixed a refcount leak, but in doing so created a
> > problem when the module is reloaded - the directory already exists, but
> > mvpp2_root is NULL, so we lose all debugfs entries. This fix has been
> > reverted.
> >
> > This is the alternative fix, where we remove the offending directory
> > whenever the driver is unloaded.
> >
> > Fixes: 21da57a23125 ("net: mvpp2: add a debugfs interface for the Header Parser")
> > Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>
>
> Reviewed-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
>
> Thanks for fixing this up properly.
>

I tested the patch and everything works as expected, thanks!

Reviewed-by: Marcin Wojtas <mw@...ihalf.com>

Best regards,
Marcin