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tty: Add fasync() hung up file operation 

VFS uses a two-stage check-and-call method for invoking file_operations
methods, without explicitly snapshotting either the file_operations ptr
or the function ptr. Since the tty core is one of the few VFS users that
changes the f_op file_operations ptr of the file descriptor (when the
tty has been hung up), and since the likelihood of the compiler generating
a reload of either f_op or the function ptr is basically nil, just define
a hung up fasync() file operation that returns an error.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
hifive-unleashed-5.1
Peter Hurley 2016-01-09 21:45:10 -08:00 committed by Greg Kroah-Hartman
parent bee6741ca0
commit f557474ca3
1 changed files with 6 additions and 0 deletions
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6
drivers/tty/tty_io.c
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@ -468,6 +468,11 @@ static long hung_up_tty_compat_ioctl(struct file *file,
return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
}
static int hung_up_tty_fasync(int fd, struct file *file, int on)
{
return -ENOTTY;
}
static const struct file_operations tty_fops = {
.llseek = no_llseek,
.read = tty_read,
@ -500,6 +505,7 @@ static const struct file_operations hung_up_tty_fops = {
.unlocked_ioctl = hung_up_tty_ioctl,
.compat_ioctl = hung_up_tty_compat_ioctl,
.release = tty_release,
.fasync = hung_up_tty_fasync,
};
static DEFINE_SPINLOCK(redirect_lock);