From: Peter Hurley <peter@hurleysoftware.com>
Date: Sat, 15 Jun 2013 14:04:24 +0000 (-0400)
Subject: n_tty: Remove echo_lock
X-Git-Tag: v3.12-rc1~182^2~178
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=17bd79074003d73f2207289b9d3ce0553d000856;p=pandora-kernel.git

n_tty: Remove echo_lock

Adding data to echo_buf (via add_echo_byte()) is guaranteed to be
single-threaded, since all callers are from the n_tty_receive_buf()
path. Processing the echo_buf can be called from either the
n_tty_receive_buf() path or the n_tty_write() path; however, these
callers are already serialized by output_lock.

Publish cumulative echo_head changes to echo_commit; process echo_buf
from echo_tail to echo_commit; remove echo_lock.

On echo_buf overrun, claim output_lock to serialize changes to
echo_tail.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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