From 33b37a33c242542fac2980b8ccd90977388b7a8d Mon Sep 17 00:00:00 2001 From: Paul Fulghum Date: Wed, 28 Jun 2006 04:26:49 -0700 Subject: [PATCH] [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 Cc: Alan Cox Cc: Theodore Ts'o Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/char/tty_io.c | 16 ++++------------ include/linux/kbd_kern.h | 4 +--- include/linux/tty.h | 1 - include/linux/tty_flip.h | 2 +- 4 files changed, 6 insertions(+), 17 deletions(-) diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c index 1f03ebf165d..8d19f7281f0 100644 --- a/drivers/char/tty_io.c +++ b/drivers/char/tty_io.c @@ -267,7 +267,6 @@ static struct tty_buffer *tty_buffer_alloc(size_t size) 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_struct *tty, size_t size) /* 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_struct *tty, size_t size) 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 *tty) { 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 @@ void tty_flip_buffer_push(struct tty_struct *tty) { 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 4eb851ece08..efe0ee4cc80 100644 --- a/include/linux/kbd_kern.h +++ b/include/linux/kbd_kern.h @@ -155,10 +155,8 @@ static inline void con_schedule_flip(struct tty_struct *t) { 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 341cc4552c0..b3b807e4b05 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -57,7 +57,6 @@ struct tty_buffer { 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 31548303ee3..eb677cf5610 100644 --- a/include/linux/tty_flip.h +++ b/include/linux/tty_flip.h @@ -12,7 +12,7 @@ static inline int tty_insert_flip_char(struct tty_struct *tty, 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; -- 2.20.1