Messages in this thread Patch in this message |  | | From | Jeff Harris <> | Subject | [PATCH] tty: Fix tcdrain hang due to tty chars_in_buffer errors | Date | Fri, 17 Jul 2009 11:07:54 -0400 |
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If a tty driver's chars_in_buffer callback reports an error, the wait loop in tty_wait_until_sent may never exit until its timeout. A tty device disconnection will hangup the tty causing the tty_wait_until_sent loop to wake-up, but if the subsequent call to chars_in_buffer reports an error instead of zero, the loop will go back to sleep instead of exiting.
A process calling tcdrain will block indefinitely if it calls tcdrain when the device is disconnected.
Signed-off-by: Jeff Harris <jeff_harris@kentrox.com> --- drivers/char/tty_ioctl.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/char/tty_ioctl.c b/drivers/char/tty_ioctl.c index ad6ba4e..306d52e 100644 --- a/drivers/char/tty_ioctl.c +++ b/drivers/char/tty_ioctl.c @@ -156,7 +156,7 @@ void tty_wait_until_sent(struct tty_struct *tty, long timeout) if (!timeout) timeout = MAX_SCHEDULE_TIMEOUT; if (wait_event_interruptible_timeout(tty->write_wait, - !tty_chars_in_buffer(tty), timeout) >= 0) { + tty_chars_in_buffer(tty) <= 0, timeout) >= 0) { if (tty->ops->wait_until_sent) tty->ops->wait_until_sent(tty, timeout); } @@ -332,7 +332,7 @@ void tty_termios_encode_baud_rate(struct ktermios *termios, int iclose = ibaud/50, oclose = obaud/50; int ibinput = 0; - if (obaud == 0) /* CD dropped */ + if (obaud == 0) /* CD dropped */ ibaud = 0; /* Clear ibaud to be sure */ termios->c_ispeed = ibaud; -- 1.5.5.1
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