From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: greg@kroah.com, linux-serial@vger.kernel.org
Subject: [PATCH 03/12] tty: Note n_tty race
Date: Wed, 27 Jun 2012 12:21:29 +0100 [thread overview]
Message-ID: <20120627112128.5678.68881.stgit@localhost.localdomain> (raw)
In-Reply-To: <20120627112102.5678.4141.stgit@localhost.localdomain>
From: Alan Cox <alan@linux.intel.com>
This was identified by Vincent Pillet with a high speed interface that uses
low latency mode. In the low latency case we have a tiny race but it can
be hit.
Signed-off-by: Alan Cox <alan@linux.intel.com>
---
drivers/tty/n_tty.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index ee1c268..4f34491 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -1432,6 +1432,12 @@ static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
*/
if (tty->receive_room < TTY_THRESHOLD_THROTTLE)
tty_throttle(tty);
+
+ /* FIXME: there is a tiny race here if the receive room check runs
+ before the other work executes and empties the buffer (upping
+ the receiving room and unthrottling. We then throttle and get
+ stuck. This has been observed and traced down by Vincent Pillet/
+ We need to address this when we sort out out the rx path locking */
}
int is_ignored(int sig)
next prev parent reply other threads:[~2012-06-27 11:05 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-27 11:21 [PATCH 01/12] f81232: correct stubbed termios handler Alan Cox
2012-06-27 11:21 ` [PATCH 02/12] usb: fix sillies in the metro USB driver Alan Cox
2012-06-27 11:21 ` Alan Cox [this message]
2012-06-27 11:21 ` [PATCH 04/12] gpio-sch: Fix leak of resource Alan Cox
2012-06-27 19:32 ` Greg KH
2012-06-27 11:21 ` [PATCH 05/12] usb, kobil: Sort out some bogus tty handling Alan Cox
2012-06-27 11:22 ` [PATCH 06/12] 8250: use the 8250 register interface not the legacy one Alan Cox
2012-06-27 22:39 ` Paul Gortmaker
2012-06-27 22:50 ` Alan Cox
2012-06-27 11:22 ` [PATCH 07/12] 8250: propogate the bugs field Alan Cox
2012-06-27 11:22 ` [PATCH 08/12] 8250: add support for ASIX devices with a FIFO bug Alan Cox
2012-06-27 11:22 ` [PATCH 10/12] tty: tidy up the RESET_TERMIOS case Alan Cox
2012-06-27 11:23 ` [PATCH 11/12] vt: fix the keyboard/led locking Alan Cox
2012-06-27 11:23 ` [PATCH 12/12] tty: Move the handling of the tty release logic Alan Cox
2012-06-27 19:35 ` [PATCH 01/12] f81232: correct stubbed termios handler Greg KH
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