From: Johan Hovold <johan@kernel.org>
To: Oliver Neukum <oneukum@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org
Subject: Re: [PATCH] USB: cdc-acm: fix racy TIOCMIWAIT implementation
Date: Mon, 7 Sep 2026 11:13:16 +0200 [thread overview]
Message-ID: <ap6ALMESM5SMQhFV@hovoldconsulting.com> (raw)
In-Reply-To: <ap56NTVMq8GlbjmR@hovoldconsulting.com>
On Mon, Sep 07, 2026 at 10:47:49AM +0200, Johan Hovold wrote:
> On Mon, Sep 07, 2026 at 10:17:38AM +0200, Oliver Neukum wrote:
> > On 07.09.26 08:55, Johan Hovold wrote:
> > > The wakeup condition needs to be checked after adding the task to the
> > > waitqueue and updating the task state to avoid missing a racing modem
> > > status update or disconnect.
> >
> > I am sorry, but in this case I have to ask:
> > Isn't TIOCMIWAIT inherently racy against the hardware?
>
> What do you mean?
Ok, I think I see what you're getting at. Nothing prevents a modem
status change just before calling TIOCMIWAIT from being missed. That is
indeed a general problem with the interface.
Johan
next prev parent reply other threads:[~2026-09-07 9:13 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-07 6:55 Johan Hovold
2026-09-07 8:17 ` Oliver Neukum
2026-09-07 8:47 ` Johan Hovold
2026-09-07 9:13 ` Johan Hovold [this message]
2026-09-07 9:50 ` Oliver Neukum
2026-09-07 10:01 ` Johan Hovold
2026-09-07 10:28 ` Oliver Neukum
2026-09-07 11:38 ` Johan Hovold
2026-09-07 12:46 ` Oliver Neukum
2026-09-07 13:03 ` Johan Hovold
2026-09-08 6:54 ` Oliver Neukum
2026-09-08 7:12 ` Johan Hovold
2026-09-08 9:23 ` Oliver Neukum
2026-09-11 6:57 ` Johan Hovold
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