diff options
| author | Peter Hurley <peter@hurleysoftware.com> | 2016-01-10 08:45:09 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-01-28 22:58:02 +0300 |
| commit | bee6741ca022f051ea1b46e16fb2ff0097643181 (patch) | |
| tree | 9d35e064e4a4013328ee3c74f9dc8833534918c5 /drivers/tty/tty_io.c | |
| parent | 33d7136336a94feade73b08b9c4bd1420df4e572 (diff) | |
| download | linux-bee6741ca022f051ea1b46e16fb2ff0097643181.tar.xz | |
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/tty_io.c')
| -rw-r--r-- | drivers/tty/tty_io.c | 8 |
1 files changed, 0 insertions, 8 deletions
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index c5b4274584dc..7533ab1abe72 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -2219,7 +2219,6 @@ static unsigned int tty_poll(struct file *filp, poll_table *wait) static int __tty_fasync(int fd, struct file *filp, int on) { struct tty_struct *tty = file_tty(filp); - struct tty_ldisc *ldisc; unsigned long flags; int retval = 0; @@ -2230,13 +2229,6 @@ static int __tty_fasync(int fd, struct file *filp, int on) if (retval <= 0) goto out; - ldisc = tty_ldisc_ref(tty); - if (ldisc) { - if (ldisc->ops->fasync) - ldisc->ops->fasync(tty, on); - tty_ldisc_deref(ldisc); - } - if (on) { enum pid_type type; struct pid *pid; |