linux-kernel - Re: [PATCH 1/2] serial: core: Don't drop DTR if system console

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Message-ID: <20140610120136.2c2cb881@alan.etchedpixels.co.uk>
Date:	Tue, 10 Jun 2014 12:01:36 +0100
From:	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>
To:	Peter Hurley <peter@...leysoftware.com>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
	Valerio Vanni <valerio.vanni@...ind.it>
Subject: Re: [PATCH 1/2] serial: core: Don't drop DTR if system console

> This patch only affects the line state if the last tty reference is closed
> or the tty is hung up by software (like on controlling process exit).
> In this case, any login session is already dying, and it would not be possible
> to hijack a live session. A successful re-login is still required.

It breaks the other direction - yes sorry.
 
> Notwithstanding what I wrote above, this patch does change behavior
> with remote consoles, which may be unacceptable.
 
> For example, if the remote user logs out, the current behavior hangs up
> the modem (if HUPCL), whereas the patch behavior just presents a new
> login prompt.

which means the modem will probably no longer answer calls.

> So yeah, I agree; this patch should be dropped.

Possibly we should also fix this the other way in tty_port_shutdown,
which does wrongly skip dtr/rts handling of consoles.

As far as I can see providing HUPCL is clear the desired console
behaviour for most situations with a remote console link is obtained.

Alan
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