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Date: Mon, 8 Jun 2026 17:36:38 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: Rosen Penev <rosenp@gmail.com>
Cc: Jacob Keller <jacob.e.keller@intel.com>, netdev@vger.kernel.org, Andrew
 Lunn <andrew+netdev@lunn.ch>, "David S. Miller" <davem@davemloft.net>, Eric
 Dumazet <edumazet@google.com>, Paolo Abeni <pabeni@redhat.com>, Jeff Garzik
 <jeff@garzik.org>, Roland Dreier <rdreier@cisco.com>, open list
 <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH net] net: ibm: emac: mal: fix potential system hang in
 mal_remove()
Message-ID: <20260608173638.74da73fe@kernel.org>
In-Reply-To: <CAKxU2N8oh03r2-zJhbOXF0Qqx7RzNSX=zq+i6Ld1c9YXJqDfKQ@mail.gmail.com>
References: <20260603230821.5619-1-rosenp@gmail.com>
	<f49d5ac6-ef78-4530-a420-d94e612581aa@intel.com>
	<CAKxU2N8oh03r2-zJhbOXF0Qqx7RzNSX=zq+i6Ld1c9YXJqDfKQ@mail.gmail.com>
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On Thu, 4 Jun 2026 16:03:43 -0700 Rosen Penev wrote:
> > > -     if (!list_empty(&mal->list))
> > > +     if (!list_empty(&mal->list)) {
> > > +             napi_disable(&mal->napi);
> > >               /* This is *very* bad */
> > >               WARN(1, KERN_EMERG
> > >                      "mal%d: commac list is not empty on remove!\n",
> > >                      mal->index);  
> >
> > This one doesn't make sense to me. The list_empty check does a WARN()
> > indicating that this is not supposed to happen.
> >
> > This implies that list_empty should be true, otherwise we'd see a WARN
> > every time mal_remove is called.
> >
> > But in that case, we'd have been calling napi_disable incorrectly in
> > most cases where it was previously unsafe according to your claim.
> >
> > At best, this list_empty check is the wrong way to tell if the napi is
> > disabled, at worst, this whole change is pointless.  
> I asked the AI. It doesn't agree:

FTR I agree with Jake, the patch seems to indicate bigger structural
issues. Then again I don't want to encourage the stream of patches
to this driver so let me just apply this..