From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751251AbWFZR6g (ORCPT ); Mon, 26 Jun 2006 13:58:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751254AbWFZR6f (ORCPT ); Mon, 26 Jun 2006 13:58:35 -0400 Received: from adsl-70-250-156-241.dsl.austtx.swbell.net ([70.250.156.241]:162 "EHLO gw.microgate.com") by vger.kernel.org with ESMTP id S1751251AbWFZR6T (ORCPT ); Mon, 26 Jun 2006 13:58:19 -0400 Subject: [PATCH] remove active field from tty buffer structure From: Paul Fulghum To: Andrew Morton Cc: Alan Cox , Linux Kernel Mailing List Content-Type: text/plain Date: Mon, 26 Jun 2006 12:57:55 -0500 Message-Id: <1151344675.32146.17.camel@amdx2.microgate.com> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-4.fc4) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Remove 'active' field from tty buffer structure. This was added in 2.6.16 as part of a patch to make the new tty buffering SMP safe. This field is unnecessary with the more intelligently written flush_to_ldisc that adds receive_room handling. Removing this field reverts to simpler logic where the tail buffer is always the 'active' buffer, which should not be freed by flush_to_ldisc. (active == buffer being filled with new data) The result is simpler, smaller, and faster tty buffer code. Signed-off-by: Paul Fulghum --- a/include/linux/tty.h 2006-06-26 10:13:22.000000000 -0500 +++ b/include/linux/tty.h 2006-06-26 09:55:25.000000000 -0500 @@ -58,7 +58,6 @@ struct tty_buffer { unsigned char *flag_buf_ptr; int used; int size; - int active; int commit; int read; /* Data points here */ --- a/include/linux/tty_flip.h 2006-06-17 20:49:35.000000000 -0500 +++ b/include/linux/tty_flip.h 2006-06-26 10:17:11.000000000 -0500 @@ -12,7 +12,7 @@ static inline int tty_insert_flip_char(s unsigned char ch, char flag) { struct tty_buffer *tb = tty->buf.tail; - if (tb && tb->active && tb->used < tb->size) { + if (tb && tb->used < tb->size) { tb->flag_buf_ptr[tb->used] = flag; tb->char_buf_ptr[tb->used++] = ch; return 1; --- a/include/linux/kbd_kern.h 2006-06-26 10:13:22.000000000 -0500 +++ b/include/linux/kbd_kern.h 2006-06-26 10:02:41.000000000 -0500 @@ -155,10 +155,8 @@ static inline void con_schedule_flip(str { unsigned long flags; spin_lock_irqsave(&t->buf.lock, flags); - if (t->buf.tail != NULL) { - t->buf.tail->active = 0; + if (t->buf.tail != NULL) t->buf.tail->commit = t->buf.tail->used; - } spin_unlock_irqrestore(&t->buf.lock, flags); schedule_work(&t->buf.work); } --- a/drivers/char/tty_io.c 2006-06-26 10:13:22.000000000 -0500 +++ b/drivers/char/tty_io.c 2006-06-26 09:55:05.000000000 -0500 @@ -267,7 +267,6 @@ static struct tty_buffer *tty_buffer_all p->used = 0; p->size = size; p->next = NULL; - p->active = 0; p->commit = 0; p->read = 0; p->char_buf_ptr = (char *)(p->data); @@ -327,10 +326,9 @@ int tty_buffer_request_room(struct tty_s /* OPTIMISATION: We could keep a per tty "zero" sized buffer to remove this conditional if its worth it. This would be invisible to the callers */ - if ((b = tty->buf.tail) != NULL) { + if ((b = tty->buf.tail) != NULL) left = b->size - b->used; - b->active = 1; - } else + else left = 0; if (left < size) { @@ -338,12 +336,10 @@ int tty_buffer_request_room(struct tty_s if ((n = tty_buffer_find(tty, size)) != NULL) { if (b != NULL) { b->next = n; - b->active = 0; b->commit = b->used; } else tty->buf.head = n; tty->buf.tail = n; - n->active = 1; } else size = left; } @@ -404,10 +400,8 @@ void tty_schedule_flip(struct tty_struct { unsigned long flags; spin_lock_irqsave(&tty->buf.lock, flags); - if (tty->buf.tail != NULL) { - tty->buf.tail->active = 0; + if (tty->buf.tail != NULL) tty->buf.tail->commit = tty->buf.tail->used; - } spin_unlock_irqrestore(&tty->buf.lock, flags); schedule_delayed_work(&tty->buf.work, 1); } @@ -2903,10 +2897,8 @@ void tty_flip_buffer_push(struct tty_str { unsigned long flags; spin_lock_irqsave(&tty->buf.lock, flags); - if (tty->buf.tail != NULL) { - tty->buf.tail->active = 0; + if (tty->buf.tail != NULL) tty->buf.tail->commit = tty->buf.tail->used; - } spin_unlock_irqrestore(&tty->buf.lock, flags); if (tty->low_latency)