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Date:   Mon, 14 Mar 2022 08:21:30 +0100
From:   "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>
To:     Vladimir Oltean <vladimir.oltean@nxp.com>
Cc:     Daniel Suchy <danny@danysek.cz>,
        "davem@davemloft.net" <davem@davemloft.net>,
        "rafael.richter@gin.de" <rafael.richter@gin.de>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: patch problem - mv88e6xxx: flush switchdev FDB workqueue
Message-ID: <Yi7s+vh3GBTVtDN2@kroah.com>
References: <ccf51795-5821-203d-348e-295aabbdc735@danysek.cz>
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 <Yi7i+pebGu0NoIsF@kroah.com>
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On Mon, Mar 14, 2022 at 07:38:50AM +0100, gregkh@linuxfoundation.org wrote:
> On Sun, Mar 13, 2022 at 02:10:31PM +0000, Vladimir Oltean wrote:
> > Hi Daniel,
> > 
> > On Sun, Mar 13, 2022 at 03:03:07PM +0100, Daniel Suchy wrote:
> > > Hello,
> > > 
> > > I noticed boot problems on my Turris Omnia (with Marvell 88E6176 switch
> > > chip) after "net: dsa: mv88e6xxx: flush switchdev FDB workqueue before
> > > removing VLAN" commit https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2566a89b9e163b2fcd104d6005e0149f197b8a48
> > > 
> > > Within logs I catched hung kernel tasks (see below), at least first is
> > > related to DSA subsystem.
> > > 
> > > When I revert this patch, everything works as expected and without any
> > > issues.
> > > 
> > > In my setup, I have few vlans on affected switch (i'm using ifupdown2 v3.0
> > > with iproute2 5.16 for configuration).
> > > 
> > > It seems your this patch introduces some new problem (at least for 5.15
> > > kernels). I suggest revert this patch.
> > > 
> > > - Daniel
> > 
> > Oh wow, I'm terribly sorry. Yes, this patch shouldn't have been
> > backported to kernel 5.15 and below, but I guess I missed the
> > backport notification email and forgot to tell Greg about this.
> > Patch "net: dsa: mv88e6xxx: flush switchdev FDB workqueue before
> > removing VLAN" needs to be immediately reverted from these trees.
> > 
> > Greg, to avoid this from happening in the future, would something like
> > this work? Is this parsed in some way?
> > 
> > Depends-on: 0faf890fc519 ("net: dsa: drop rtnl_lock from dsa_slave_switchdev_event_work") # which first appeared in v5.16
> 
> The "Fixes:" tag will solve this, please just use that in the future.

Ah, you did have a fixes tag here, so then use the way to say "you also
need to add another patch here" by adding the sha to the line for the
stable tree:
	cc: stable@vger.kernel.org # 0faf890fc519

So, should I just backport that commit instead?  The "Fixes:" line says
this needs to be backported to 4.14, which is why I added it to these
trees.

thanks,

greg k-h