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 /include | |
| parent | 33d7136336a94feade73b08b9c4bd1420df4e572 (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 'include')
| -rw-r--r-- | include/linux/tty_ldisc.h | 6 |
1 files changed, 0 insertions, 6 deletions
diff --git a/include/linux/tty_ldisc.h b/include/linux/tty_ldisc.h index 6101ab8dc148..3971cf0eb467 100644 --- a/include/linux/tty_ldisc.h +++ b/include/linux/tty_ldisc.h @@ -98,11 +98,6 @@ * seek to perform this action quickly but should wait until * any pending driver I/O is completed. * - * void (*fasync)(struct tty_struct *, int on) - * - * Notify line discipline when signal-driven I/O is enabled or - * disabled. - * * void (*dcd_change)(struct tty_struct *tty, unsigned int status) * * Tells the discipline that the DCD pin has changed its status. @@ -202,7 +197,6 @@ struct tty_ldisc_ops { char *fp, int count); void (*write_wakeup)(struct tty_struct *); void (*dcd_change)(struct tty_struct *, unsigned int); - void (*fasync)(struct tty_struct *tty, int on); int (*receive_buf2)(struct tty_struct *, const unsigned char *cp, char *fp, int count); |