diff options
| author | Peter Hurley <peter@hurleysoftware.com> | 2016-01-10 06:45:09 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-01-28 20:58:02 +0100 |
| commit | bee6741ca022f051ea1b46e16fb2ff0097643181 (patch) | |
| tree | 9d35e064e4a4013328ee3c74f9dc8833534918c5 | |
| parent | n_tty: Always wake up read()/poll() if new input (diff) | |
| download | linux-bee6741ca022f051ea1b46e16fb2ff0097643181.tar.xz linux-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>
| -rw-r--r-- | drivers/tty/n_tty.c | 5 | ||||
| -rw-r--r-- | drivers/tty/tty_io.c | 8 | ||||
| -rw-r--r-- | include/linux/tty_ldisc.h | 6 |
3 files changed, 0 insertions, 19 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, }; 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; 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); |