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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/n_tty.c
parente0ac4761fa52acda90f9f53819c81474b511e3af (diff)
downloadlinux-linaro-stable-817d6d3bceaf34c99f5343820f9b9e6021f0655c.tar.gz
[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/n_tty.c')
-rw-r--r--drivers/char/n_tty.c6
1 files changed, 1 insertions, 5 deletions
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);