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[PATCH] remove TTY_DONT_FLIP

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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>
This commit is contained in:
Paul Fulghum
2006-06-28 04:26:47 -07:00
committed by Linus Torvalds
parent e0ac4761fa
commit 817d6d3bce
9 changed files with 7 additions and 42 deletions
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7
drivers/serial/jsm/jsm_tty.c
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@@ -588,13 +588,6 @@ void jsm_input(struct jsm_channel *ch)
len = min(len, (N_TTY_BUF_SIZE - 1) - tp->read_cnt);
ld = tty_ldisc_ref(tp);
/*
* If the DONT_FLIP flag is on, don't flush our buffer, and act
* like the ld doesn't have any space to put the data right now.
*/
if (test_bit(TTY_DONT_FLIP, &tp->flags))
len = 0;
/*
* If we were unable to get a reference to the ld,
* don't flush our buffer, and act like the ld doesn't