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: Tue, 8 Sep 2026 09:12:35 +0200 [thread overview]
Message-ID: <ap-1YzIoyYsH_3V-@hovoldconsulting.com> (raw)
In-Reply-To: <a9db0fce-2a2d-4896-a3c3-2afff4080168@suse.com>
On Tue, Sep 08, 2026 at 08:54:36AM +0200, Oliver Neukum wrote:
>
>
> On 07.09.26 15:03, Johan Hovold wrote:
> > On Mon, Sep 07, 2026 at 02:46:16PM +0200, Oliver Neukum wrote:
> >>
>
> >> We could do that and it would indeed be simpler.
> >>
> >> But it would change the semantics so that past status changes
> >> no longer show up in TIOCMIWAIT. Is that really a good idea?
> >
> > Yes, as the current behaviour is both non-standard and inconsistent.
> >
> > If you have multiple tasks waiting waiting on status change, then only
> > one of them will detect it, for example.
> >
> > And if there are multiple changes (before or during TIOCMIWAIT) events
> > may be lost too.
>
> Very well. Ample reasons. Do you have a patch or do you want me to fix it?
I sent a v2 yesterday that should take care of it all:
https://lore.kernel.org/all/20260907095130.130636-1-johan@kernel.org/
Johan
next prev parent reply other threads:[~2026-09-08 7:12 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-07 6:55 [PATCH] USB: cdc-acm: fix racy TIOCMIWAIT implementation Johan Hovold
2026-09-07 8:17 ` Oliver Neukum
2026-09-07 8:47 ` Johan Hovold
2026-09-07 9:13 ` Johan Hovold
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 [this message]
2026-09-08 9:23 ` Oliver Neukum
2026-09-11 6:57 ` Johan Hovold
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