linux-kernel - Re: [PATCH 4/5] usb_serial: Kill port mutex

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <Pine.LNX.4.44L0.0910071434290.3051-100000@iolanthe.rowland.org>
Date:	Wed, 7 Oct 2009 14:52:21 -0400 (EDT)
From:	Alan Stern <stern@...land.harvard.edu>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
cc:	Oliver Neukum <oliver@...kum.org>, Greg KH <greg@...ah.com>,
	Kernel development list <linux-kernel@...r.kernel.org>,
	USB list <linux-usb@...r.kernel.org>
Subject: Re: [PATCH 4/5] usb_serial: Kill port mutex

On Wed, 7 Oct 2009, Alan Cox wrote:

> > > It would probably be cleaner if they could lock against each other
> > 
> > What you mean isn't clear.  After all, open sometimes has to call
> > resume.  So how could resume lock against open?
> 
> Probably it needs a counting lock as the code is currently structured -
> which is a bit ugly. What paths do we end up going through the device
> open method into resume in the same thread ?

Currently there are no such paths.  I keep forgetting that the resume
is done in serial_install() rather than serial_open().  Eventually the
tty_port reorganization will probably force the resume to move into the
activate method.

However in the option and sierra drivers there is a perverse path from
close to resume: Both their close methods call
usb_autopm_get_interface().  This could be removed without much
trouble; perhaps we should do so.

Alan Stern

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/