Author: Paul Fulghum <[EMAIL PROTECTED]>
AuthorDate: Wed May 9 02:33:38 2007 -0700
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Wed May 9 12:30:49 2007 -0700
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 <[EMAIL PROTECTED]>
Acked-by: Alan Cox <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
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
@@ -934,13 +934,6 @@ restart:
- * 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:
+ * 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;
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