From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755372Ab3DOPaX (ORCPT ); Mon, 15 Apr 2013 11:30:23 -0400 Received: from mailout02.c08.mtsvc.net ([205.186.168.190]:45543 "EHLO mailout02.c08.mtsvc.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754827Ab3DOPaN (ORCPT ); Mon, 15 Apr 2013 11:30:13 -0400 From: Peter Hurley To: Greg Kroah-Hartman Cc: Jiri Slaby , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, Peter Hurley Subject: [PATCH 3/9] n_tty: Replace echo_cnt with computed value Date: Mon, 15 Apr 2013 11:29:41 -0400 Message-Id: <1366039787-8719-4-git-send-email-peter@hurleysoftware.com> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1366039787-8719-1-git-send-email-peter@hurleysoftware.com> References: <1366039567-8620-1-git-send-email-peter@hurleysoftware.com> <1366039787-8719-1-git-send-email-peter@hurleysoftware.com> X-Authenticated-User: 125194 peter@hurleysoftware.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Prepare for lockless echo_buf handling; compute current byte count of echo_buf from head and tail indices. Signed-off-by: Peter Hurley --- drivers/tty/n_tty.c | 20 +++++++------------- 1 file changed, 7 insertions(+), 13 deletions(-) diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c index 85334f8..cd41733 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -110,7 +110,6 @@ struct n_tty_data { unsigned char *echo_buf; size_t echo_head; size_t echo_tail; - unsigned int echo_cnt; /* protected by output lock */ unsigned int column; @@ -335,7 +334,7 @@ static void reset_buffer_flags(struct n_tty_data *ldata) ldata->read_head = ldata->canon_head = ldata->read_tail = 0; mutex_lock(&ldata->echo_lock); - ldata->echo_head = ldata->echo_tail = ldata->echo_cnt = 0; + ldata->echo_head = ldata->echo_tail = 0; mutex_unlock(&ldata->echo_lock); ldata->erasing = 0; @@ -653,7 +652,7 @@ static void process_echoes(struct tty_struct *tty) size_t tail; unsigned char c; - if (!ldata->echo_cnt) + if (ldata->echo_head == ldata->echo_tail) return; mutex_lock(&ldata->output_lock); @@ -662,7 +661,7 @@ static void process_echoes(struct tty_struct *tty) space = tty_write_room(tty); tail = ldata->echo_tail; - nr = ldata->echo_cnt; + nr = ldata->echo_head - ldata->echo_tail; while (nr > 0) { c = echo_buf(ldata, tail); if (c == ECHO_OP_START) { @@ -779,7 +778,6 @@ static void process_echoes(struct tty_struct *tty) } ldata->echo_tail = tail; - ldata->echo_cnt = nr; mutex_unlock(&ldata->echo_lock); mutex_unlock(&ldata->output_lock); @@ -800,24 +798,20 @@ static void process_echoes(struct tty_struct *tty) static void add_echo_byte(unsigned char c, struct n_tty_data *ldata) { - if (ldata->echo_cnt == N_TTY_BUF_SIZE) { + if (ldata->echo_head - ldata->echo_tail == N_TTY_BUF_SIZE) { size_t head = ldata->echo_head; /* * Since the buffer start position needs to be advanced, * be sure to step by a whole operation byte group. */ if (echo_buf(ldata, head) == ECHO_OP_START) { - if (echo_buf(ldata, head + 1) == ECHO_OP_ERASE_TAB) { + if (echo_buf(ldata, head + 1) == ECHO_OP_ERASE_TAB) ldata->echo_tail += 3; - ldata->echo_cnt -= 2; - } else { + else ldata->echo_tail += 2; - ldata->echo_cnt -= 1; - } } else ldata->echo_tail++; - } else - ldata->echo_cnt++; + } *echo_buf_addr(ldata, ldata->echo_head++) = c; } -- 1.8.1.2