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authorPaul Fulghum <paulkf@microgate.com>2006-06-28 07:26:47 -0400
committerLinus Torvalds <torvalds@g5.osdl.org>2006-06-28 17:59:05 -0400
commit817d6d3bceaf34c99f5343820f9b9e6021f0655c (patch)
tree651104833124262db46c2a372b7adb55289cd8dd /drivers/char/tty_io.c
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/tty_io.c')
-rw-r--r--drivers/char/tty_io.c15
1 files changed, 2 insertions, 13 deletions
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:
784 } 784 }
785 785
786 clear_bit(TTY_LDISC, &tty->flags); 786 clear_bit(TTY_LDISC, &tty->flags);
787 clear_bit(TTY_DONT_FLIP, &tty->flags); 787 if (o_tty)
788 if (o_tty) {
789 clear_bit(TTY_LDISC, &o_tty->flags); 788 clear_bit(TTY_LDISC, &o_tty->flags);
790 clear_bit(TTY_DONT_FLIP, &o_tty->flags);
791 }
792 spin_unlock_irqrestore(&tty_ldisc_lock, flags); 789 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
793 790
794 /* 791 /*
@@ -1955,7 +1952,6 @@ static void release_dev(struct file * filp)
1955 * race with the set_ldisc code path. 1952 * race with the set_ldisc code path.
1956 */ 1953 */
1957 clear_bit(TTY_LDISC, &tty->flags); 1954 clear_bit(TTY_LDISC, &tty->flags);
1958 clear_bit(TTY_DONT_FLIP, &tty->flags);
1959 cancel_delayed_work(&tty->buf.work); 1955 cancel_delayed_work(&tty->buf.work);
1960 1956
1961 /* 1957 /*
@@ -2784,13 +2780,6 @@ static void flush_to_ldisc(void *private_)
2784 if (disc == NULL) /* !TTY_LDISC */ 2780 if (disc == NULL) /* !TTY_LDISC */
2785 return; 2781 return;
2786 2782
2787 if (test_bit(TTY_DONT_FLIP, &tty->flags)) {
2788 /*
2789 * Do it after the next timer tick:
2790 */
2791 schedule_delayed_work(&tty->buf.work, 1);
2792 goto out;
2793 }
2794 spin_lock_irqsave(&tty->buf.lock, flags); 2783 spin_lock_irqsave(&tty->buf.lock, flags);
2795 while((tbuf = tty->buf.head) != NULL) { 2784 while((tbuf = tty->buf.head) != NULL) {
2796 while ((count = tbuf->commit - tbuf->read) != 0) { 2785 while ((count = tbuf->commit - tbuf->read) != 0) {
@@ -2809,7 +2798,7 @@ static void flush_to_ldisc(void *private_)
2809 tty_buffer_free(tty, tbuf); 2798 tty_buffer_free(tty, tbuf);
2810 } 2799 }
2811 spin_unlock_irqrestore(&tty->buf.lock, flags); 2800 spin_unlock_irqrestore(&tty->buf.lock, flags);
2812out: 2801
2813 tty_ldisc_deref(disc); 2802 tty_ldisc_deref(disc);
2814} 2803}
2815 2804