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| author | Paul Fulghum <paulkf@microgate.com> | 2006-06-28 04:26:47 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-06-28 14:59:05 -0700 |
| commit | 817d6d3bceaf34c99f5343820f9b9e6021f0655c (patch) | |
| tree | 651104833124262db46c2a372b7adb55289cd8dd /drivers/char/n_tty.c | |
| parent | e0ac4761fa52acda90f9f53819c81474b511e3af (diff) | |
| download | lwn-817d6d3bceaf34c99f5343820f9b9e6021f0655c.tar.gz lwn-817d6d3bceaf34c99f5343820f9b9e6021f0655c.zip | |
[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.c | 6 |
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); |