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	Fri, 17 Apr 2026 18:04:03 +0000
Date: Fri, 17 Apr 2026 19:03:58 +0100
From: Daniel Golle <daniel@makrotopia.org>
To: Breno Leitao <leitao@debian.org>
Cc: "Chester A. Unal" <chester.a.unal@arinc9.com>,
	Andrew Lunn <andrew@lunn.ch>, Vladimir Oltean <olteanv@gmail.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>,
	Russell King <linux@armlinux.org.uk>,
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	linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-mediatek@lists.infradead.org,
	Frank Wunderlich <frank-w@public-files.de>,
	John Crispin <john@phrozen.org>
Subject: Re: [PATCH net] net: dsa: mt7530: fix .get_stats64 sleeping in
 atomic context
Message-ID: <aeJ2Di7tuIQ5RniE@makrotopia.org>
References: <79dc0ec5b6be698b14cb66339d6f63033ca2934a.1776397542.git.daniel@makrotopia.org>
 <aeJjcoHyezEgUG_Q@gmail.com>
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In-Reply-To: <aeJjcoHyezEgUG_Q@gmail.com>

On Fri, Apr 17, 2026 at 10:46:29AM -0700, Breno Leitao wrote:
> On Fri, Apr 17, 2026 at 04:55:57AM +0100, Daniel Golle wrote:
> > @@ -3404,6 +3449,9 @@ EXPORT_SYMBOL_GPL(mt7530_probe_common);
> >  void
> >  mt7530_remove_common(struct mt7530_priv *priv)
> >  {
> > +	if (priv->bus)
> > +		cancel_delayed_work_sync(&priv->stats_work);
> > +
> 
> Shouldn't you cancel the work later, after dsa_unregister_switch()?
> 
> I am wondering if the following race cannot happen:
> 
>  mt7530_remove_common()                  someone reading /proc/net/dev
>     cancel_delayed_work_sync()
>       /* returns: work neither pending
>          nor executing - true at this
>          instant */
>                                           mt7530_get_stats64()
>                                             mod_delayed_work(...)
>                                             /* work is queued again */
>     dsa_unregister_switch()
>     return

Thanks you for pointing this out.
cancel_delayed_work_sync() should be moved after dsa_unregister_switch()
to avoid this kind of race.