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References: <20220921114444.2247083-1-gregkh@linuxfoundation.org> <YyyH1oXMubeQ8KVu@shell.armlinux.org.uk>
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From:   Marcin Wojtas <mw@semihalf.com>
Date:   Thu, 22 Sep 2022 19:08:16 +0200
Message-ID: <CAPv3WKch2J4tteo68wOt_ETj_eYEKy8EC5sTwDvW6UZ-Gs_sCw@mail.gmail.com>
Subject: Re: [PATCH net] net: mvpp2: debugfs: fix problem with previous memory
 leak fix
To:     "Russell King (Oracle)" <linux@armlinux.org.uk>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, stable <stable@kernel.org>
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Hi,

Thank you both for the patches.


czw., 22 wrz 2022 o 18:05 Russell King (Oracle)
<linux@armlinux.org.uk> napisa=C5=82(a):
>
> On Wed, Sep 21, 2022 at 01:44:44PM +0200, Greg Kroah-Hartman wrote:
> > In commit fe2c9c61f668 ("net: mvpp2: debugfs: fix memory leak when usin=
g
> > debugfs_lookup()"), if the module is unloaded, the directory will still
> > be present if the module is loaded again and creating the directory wil=
l
> > fail, causing the creation of additional child debugfs entries for the
> > individual devices to fail.
> >
> > As this module never cleaned up the root directory it created, even whe=
n
> > loaded, and unloading/loading a module is not a normal operation, none
> > of would normally happen.
> >
> > To clean all of this up, use a tiny reference counted structure to hold
> > the root debugfs directory for the driver, and then clean it up when th=
e
> > last user of it is removed from the system.  This should resolve the
> > previously reported problems, and the original memory leak that
> > fe2c9c61f668 ("net: mvpp2: debugfs: fix memory leak when using
> > debugfs_lookup()") was attempting to fix.
>
> For the record... I have a better fix for this, but I haven't been able
> to get it into a state suitable for submission yet.
>
> http://www.home.armlinux.org.uk/~rmk/misc/mvpp2-debugfs.diff
>
> Not yet against the net tree. Might have time tomorrow to do that, not
> sure at the moment. Medical stuff is getting in the way. :(
>

I'd lean towards this version - it is a bit more compact. I'll try to
test that tomorrow or during the weekend.

Best regards,
Marcin