summaryrefslogtreecommitdiff
path: root/drivers/tty/n_tty.c
diff options
context:
space:
mode:
authorPeter Hurley <peter@hurleysoftware.com>2016-01-09 21:45:09 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-01-28 11:58:02 -0800
commitbee6741ca022f051ea1b46e16fb2ff0097643181 (patch)
tree9d35e064e4a4013328ee3c74f9dc8833534918c5 /drivers/tty/n_tty.c
parent33d7136336a94feade73b08b9c4bd1420df4e572 (diff)
tty, n_tty: Remove fasync() ldisc notification
Only the N_TTY line discipline implements the signal-driven i/o notification enabled/disabled by fcntl(F_SETFL, O_ASYNC). The ldisc fasync() notification is sent to the ldisc when the enable state has changed (the tty core is notified via the fasync() VFS file operation). The N_TTY line discipline used the enable state to change the wakeup condition (minimum_to_wake = 1) for notifying the signal handler i/o is available. However, just the presence of data is sufficient and necessary to signal i/o is available, so changing minimum_to_wake is unnecessary (and creates a race condition with read() and poll() which may be concurrently updating minimum_to_wake). Furthermore, since the kill_fasync() VFS helper performs no action if the fasync list is empty, calling unconditionally is preferred; if signal driven i/o just has been disabled, no signal will be sent by kill_fasync() anyway so notification of the change via the ldisc fasync() method is superfluous. Signed-off-by: Peter Hurley <peter@hurleysoftware.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.c5
1 files changed, 0 insertions, 5 deletions
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index d04f398d5de3..a93e4c7e82ae 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -2448,10 +2448,6 @@ static int n_tty_ioctl(struct tty_struct *tty, struct file *file,
}
}
-static void n_tty_fasync(struct tty_struct *tty, int on)
-{
-}
-
static struct tty_ldisc_ops n_tty_ops = {
.magic = TTY_LDISC_MAGIC,
.name = "n_tty",
@@ -2465,7 +2461,6 @@ static struct tty_ldisc_ops n_tty_ops = {
.poll = n_tty_poll,
.receive_buf = n_tty_receive_buf,
.write_wakeup = n_tty_write_wakeup,
- .fasync = n_tty_fasync,
.receive_buf2 = n_tty_receive_buf2,
};