summaryrefslogtreecommitdiff
path: root/drivers/char
diff options
context:
space:
mode:
authorPaul Fulghum <paulkf@microgate.com>2006-06-28 04:26:47 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-06-28 14:59:05 -0700
commit817d6d3bceaf34c99f5343820f9b9e6021f0655c (patch)
tree651104833124262db46c2a372b7adb55289cd8dd /drivers/char
parente0ac4761fa52acda90f9f53819c81474b511e3af (diff)
[PATCH] remove TTY_DONT_FLIP
Remove TTY_DONT_FLIP tty flag. This flag was introduced in 2.1.X kernels to prevent the N_TTY line discipline functions read_chan() and n_tty_receive_buf() from running at the same time. 2.2.15 introduced tty->read_lock to protect access to the N_TTY read buffer, which is the only state requiring protection between these two functions. The current TTY_DONT_FLIP implementation is broken for SMP, and is not universally honored by drivers that send data directly to the line discipline receive_buf function. Because TTY_DONT_FLIP is not necessary, is broken in implementation, and is not universally honored, it is removed. 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>
Diffstat (limited to 'drivers/char')
-rw-r--r--drivers/char/mxser.c1
-rw-r--r--drivers/char/n_tty.c6
-rw-r--r--drivers/char/pty.c2
-rw-r--r--drivers/char/tty_io.c15
4 files changed, 4 insertions, 20 deletions
diff --git a/drivers/char/mxser.c b/drivers/char/mxser.c
index 645d9d713aec..72cfd09091e0 100644
--- a/drivers/char/mxser.c
+++ b/drivers/char/mxser.c
@@ -996,7 +996,6 @@ static int mxser_open(struct tty_struct *tty, struct file *filp)
info->session = current->signal->session;
info->pgrp = process_group(current);
- clear_bit(TTY_DONT_FLIP, &tty->flags);
/*
status = mxser_get_msr(info->base, 0, info->port);
diff --git a/drivers/char/n_tty.c b/drivers/char/n_tty.c
index b9371d5bf790..603b9ade5eb0 100644
--- a/drivers/char/n_tty.c
+++ b/drivers/char/n_tty.c
@@ -1132,7 +1132,7 @@ static inline int input_available_p(struct tty_struct *tty, int amt)
* buffer, and once to drain the space from the (physical) beginning of
* the buffer to head pointer.
*
- * Called under the tty->atomic_read_lock sem and with TTY_DONT_FLIP set
+ * Called under the tty->atomic_read_lock sem
*
*/
@@ -1271,7 +1271,6 @@ do_it_again:
}
add_wait_queue(&tty->read_wait, &wait);
- set_bit(TTY_DONT_FLIP, &tty->flags);
while (nr) {
/* First test for status change. */
if (tty->packet && tty->link->ctrl_status) {
@@ -1315,9 +1314,7 @@ do_it_again:
break;
}
n_tty_set_room(tty);
- clear_bit(TTY_DONT_FLIP, &tty->flags);
timeout = schedule_timeout(timeout);
- set_bit(TTY_DONT_FLIP, &tty->flags);
continue;
}
__set_current_state(TASK_RUNNING);
@@ -1394,7 +1391,6 @@ do_it_again:
if (time)
timeout = time;
}
- clear_bit(TTY_DONT_FLIP, &tty->flags);
mutex_unlock(&tty->atomic_read_lock);
remove_wait_queue(&tty->read_wait, &wait);
diff --git a/drivers/char/pty.c b/drivers/char/pty.c
index 9b5a2c0e7008..0c17f61549b4 100644
--- a/drivers/char/pty.c
+++ b/drivers/char/pty.c
@@ -101,7 +101,7 @@ static void pty_unthrottle(struct tty_struct * tty)
*
* FIXME: Our pty_write method is called with our ldisc lock held but
* not our partners. We can't just take the other one blindly without
- * risking deadlocks. There is also the small matter of TTY_DONT_FLIP
+ * risking deadlocks.
*/
static int pty_write(struct tty_struct * tty, const unsigned char *buf, int count)
{
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index bd74e82d8a72..b846d87f2b56 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -784,11 +784,8 @@ restart:
}
clear_bit(TTY_LDISC, &tty->flags);
- clear_bit(TTY_DONT_FLIP, &tty->flags);
- if (o_tty) {
+ if (o_tty)
clear_bit(TTY_LDISC, &o_tty->flags);
- clear_bit(TTY_DONT_FLIP, &o_tty->flags);
- }
spin_unlock_irqrestore(&tty_ldisc_lock, flags);
/*
@@ -1955,7 +1952,6 @@ static void release_dev(struct file * filp)
* race with the set_ldisc code path.
*/
clear_bit(TTY_LDISC, &tty->flags);
- clear_bit(TTY_DONT_FLIP, &tty->flags);
cancel_delayed_work(&tty->buf.work);
/*
@@ -2784,13 +2780,6 @@ static void flush_to_ldisc(void *private_)
if (disc == NULL) /* !TTY_LDISC */
return;
- if (test_bit(TTY_DONT_FLIP, &tty->flags)) {
- /*
- * Do it after the next timer tick:
- */
- schedule_delayed_work(&tty->buf.work, 1);
- goto out;
- }
spin_lock_irqsave(&tty->buf.lock, flags);
while((tbuf = tty->buf.head) != NULL) {
while ((count = tbuf->commit - tbuf->read) != 0) {
@@ -2809,7 +2798,7 @@ static void flush_to_ldisc(void *private_)
tty_buffer_free(tty, tbuf);
}
spin_unlock_irqrestore(&tty->buf.lock, flags);
-out:
+
tty_ldisc_deref(disc);
}