linux-kernel - Re: [PATCH v2 0/9] mostly lockless tty echo

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 for Android: free password hash cracker in your pocket

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

Message-ID: <20130724000433.GA27651@kroah.com>
Date:	Tue, 23 Jul 2013 17:04:33 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	Peter Hurley <peter@...leysoftware.com>
Cc:	linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org,
	Jiri Slaby <jslaby@...e.cz>
Subject: Re: [PATCH v2 0/9] mostly lockless tty echo

On Sat, Jun 15, 2013 at 10:04:20AM -0400, Peter Hurley wrote:
> ** v2 changes **
> - Rebased on v2 of 'lockless tty flip buffers'
> 
> This 3rd of 4 patchsets implements a mostly-lockless tty echo output.
> 
> Because echoing is performed solely by the single-threaded ldisc
> receive_buf() method, most of the lockless requirements are already
> in-place. The main existing complications were;
> 1) Echoing could overrun itself. A fixed-size buffer is used to record
>    the operations necessary when outputting the echoes; the most recent
>    echo data is preserved.
> 2) An attempt to push unprocessed echoes is made by the n_tty_write method
>    (on a different thread) before attempting write output.
> 
> The overrun condition is solved by outputting the echoes in blocks and
> ensuring that at least that much space is available each time an echo
> operation is committed. At the conclusion of each flip buffer received,
> any remaining unprocessed echoes are output.
> 
> This block output method is particularly effective when there is no reader
> (the tty is output-only) and termios is misconfigured with echo enabled.
> 
> The concurrent access by the n_tty_write() method is already excluded
> by the existing output_lock mutex.

Applied, thanks.

greg k-h
--
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/