From 817d6d3bceaf34c99f5343820f9b9e6021f0655c Mon Sep 17 00:00:00 2001 From: Paul Fulghum Date: Wed, 28 Jun 2006 04:26:47 -0700 Subject: [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 Cc: Alan Cox Cc: Theodore Ts'o Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/char/n_tty.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) (limited to 'drivers/char/n_tty.c') 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); -- cgit v1.2.3