The patch titled
tty_set_ldisc() receive_room fix
has been added to the -mm tree. Its filename is
tty_set_ldisc-receive_room-fix.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: tty_set_ldisc() receive_room fix
From: Paul Fulghum <paulkf@xxxxxxxxxxxxx>
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@xxxxxxxxxxxxx>
Cc: Alan Cox <alan@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/char/tty_io.c | 14 +++++++-------
1 files changed, 7 insertions(+), 7 deletions(-)
diff -puN drivers/char/tty_io.c~tty_set_ldisc-receive_room-fix drivers/char/tty_io.c
--- a/drivers/char/tty_io.c~tty_set_ldisc-receive_room-fix
+++ a/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;
_
Patches currently in -mm which might be from paulkf@xxxxxxxxxxxxx are
drivers-char-synclinkc-check-kmalloc-return-value.patch
synclink_gt-use-dynamic-tty-device-registration.patch
tty_set_ldisc-receive_room-fix.patch
tty-add-compat_ioctl.patch
tty-add-compat_ioctl-fix.patch
synclink_gt-add-compat_ioctl.patch
synclink_gt-add-compat_ioctl-fix.patch
-
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