linux-kernel - Re: [PATCH net] mvpp2: fix panic on module removal

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Message-ID: <20190801120038.GA14470@kwain>
Date:   Thu, 1 Aug 2019 14:00:38 +0200
From:   Antoine Tenart <antoine.tenart@...tlin.com>
To:     Matteo Croce <mcroce@...hat.com>
Cc:     Antoine Tenart <antoine.tenart@...tlin.com>,
        netdev <netdev@...r.kernel.org>,
        Miquel Raynal <miquel.raynal@...e-electrons.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Lorenzo Bianconi <lorenzo@...nel.org>,
        Maxime Chevallier <maxime.chevallier@...tlin.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH net] mvpp2: fix panic on module removal

On Thu, Aug 01, 2019 at 01:46:39PM +0200, Matteo Croce wrote:
> On Thu, Aug 1, 2019 at 9:18 AM Antoine Tenart
> <antoine.tenart@...tlin.com> wrote:
> > On Wed, Jul 31, 2019 at 08:31:16PM +0200, Matteo Croce wrote:
> > >
> > > diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
> > > index c51f1d5b550b..5002d51fc9d6 100644
> > > --- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
> > > +++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
> > > @@ -5760,7 +5760,6 @@ static int mvpp2_remove(struct platform_device *pdev)
> > >       mvpp2_dbgfs_cleanup(priv);
> > >
> > >       flush_workqueue(priv->stats_queue);
> > > -     destroy_workqueue(priv->stats_queue);
> > >
> > >       fwnode_for_each_available_child_node(fwnode, port_fwnode) {
> > >               if (priv->port_list[i]) {
> > > @@ -5770,6 +5769,8 @@ static int mvpp2_remove(struct platform_device *pdev)
> > >               i++;
> > >       }
> >
> > Shouldn't you also move flush_workqueue() here?
> 
> I think that that flush it's unneeded at all, as all port remove calls
> cancel_delayed_work_sync().
> 
> I tried removing it and it doesn't crash on rmmod.

I was wondering this, and looking at the documentation it seems to me
removing flush_workqueue() should be fine.

Thanks!
Antoine

-- 
Antoine Ténart, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com