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author | Paul Fulghum <paulkf@microgate.com> | 2007-05-09 02:33:38 -0700 |
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committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-05-09 12:30:49 -0700 |
commit | ae030e435f5400cff77c52506a8d3d7278f0947c (patch) | |
tree | 73520671c56d8a54dff2a4969201251815ca93de /drivers | |
parent | 55c0d1f83e481dd6c77f52f7dcfeb043b8b740fa (diff) | |
download | op-kernel-dev-ae030e435f5400cff77c52506a8d3d7278f0947c.zip op-kernel-dev-ae030e435f5400cff77c52506a8d3d7278f0947c.tar.gz |
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>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/char/tty_io.c | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c index 7710a6a..bf5a001 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; |