[PATCH] remove active field from tty buffer structure
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 <paulkf@microgate.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 1f03ebf..8d19f72 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -267,7 +267,6 @@
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 @@
/* 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 @@
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 @@
{
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);
}
@@ -2902,10 +2896,8 @@
{
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)
diff --git a/include/linux/kbd_kern.h b/include/linux/kbd_kern.h
index 4eb851e..efe0ee4 100644
--- a/include/linux/kbd_kern.h
+++ b/include/linux/kbd_kern.h
@@ -155,10 +155,8 @@
{
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);
}
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 341cc45..b3b807e 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -57,7 +57,6 @@
unsigned char *flag_buf_ptr;
int used;
int size;
- int active;
int commit;
int read;
/* Data points here */
diff --git a/include/linux/tty_flip.h b/include/linux/tty_flip.h
index 3154830..eb677cf 100644
--- a/include/linux/tty_flip.h
+++ b/include/linux/tty_flip.h
@@ -12,7 +12,7 @@
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;