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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 /include
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 'include')
-rw-r--r--include/linux/tty_ldisc.h6
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);