diff options
| author |   Peter Hurley <peter@hurleysoftware.com> | 2016-01-09 21:45:09 -0800 |
|---|---|---|
| committer |   Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-01-28 11:58:02 -0800 |
| commit | bee6741ca022f051ea1b46e16fb2ff0097643181 (patch) | |
| tree | 9d35e064e4a4013328ee3c74f9dc8833534918c5 /drivers/tty/n_tty.c | |
| parent | n_tty: Always wake up read()/poll() if new input (diff) | |
| download | linux-dev-bee6741ca022f051ea1b46e16fb2ff0097643181.tar.xz linux-dev-bee6741ca022f051ea1b46e16fb2ff0097643181.zip | |
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.c | 5 |
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, }; |