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authorAlan Cox <alan@lxorguk.ukuu.org.uk>2012-06-22 15:40:20 (GMT)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-06-27 02:25:38 (GMT)
commit0a44ab41eb833d07e3ec807d87151c7164d4f075 (patch)
tree8073a65697742960db6bb61fecbc70bd06b15fb1 /drivers/tty/n_tty.c
parentfc915c8b930c3114f2a838f7e2cd8789ad6fedc3 (diff)
downloadlinux-0a44ab41eb833d07e3ec807d87151c7164d4f075.tar.xz
tty: note race we need to fix
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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/n_tty.c')
-rw-r--r--drivers/tty/n_tty.c6
1 files changed, 6 insertions, 0 deletions
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)