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authorPaul Fulghum <paulkf@microgate.com>2007-05-09 02:33:38 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-05-09 12:30:49 -0700
commitae030e435f5400cff77c52506a8d3d7278f0947c (patch)
tree73520671c56d8a54dff2a4969201251815ca93de
parent55c0d1f83e481dd6c77f52f7dcfeb043b8b740fa (diff)
tty_set_ldisc() receive_room fix
Fix tty_set_ldisc in tty_io.c so that tty->receive_room is only cleared if actually changing line disciplines. Without this fix a problem occurs when requesting the line discipline to change to the same line discipline. In this case tty->receive_room is cleared but ldisc->open() is not called to set tty->receive_room back to a sane value. The result is that tty->receive_room is stuck at 0 preventing the tty flip buffer from passing receive data to the line discipline. For example: a switch from N_TTY to N_TTY followed by a select() call for read input results in data never being received because tty->receive_room is stuck at zero. A switch from N_TTY to N_TTY followed by a read() call works because the read() call itself sets tty->receive_room correctly (but select does not). Previously (< 2.6.18) this was not a problem because the tty flip buffer pushed data to the line discipline without regard for tty->receive room. Signed-off-by: Paul Fulghum <paulkf@microgate.com> Acked-by: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--drivers/char/tty_io.c14
1 files changed, 7 insertions, 7 deletions
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 7710a6a77d9..bf5a00145c0 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -934,13 +934,6 @@ restart:
return -EINVAL;
/*
- * No more input please, we are switching. The new ldisc
- * will update this value in the ldisc open function
- */
-
- tty->receive_room = 0;
-
- /*
* Problem: What do we do if this blocks ?
*/
@@ -951,6 +944,13 @@ restart:
return 0;
}
+ /*
+ * No more input please, we are switching. The new ldisc
+ * will update this value in the ldisc open function
+ */
+
+ tty->receive_room = 0;
+
o_ldisc = tty->ldisc;
o_tty = tty->link;