Commit f557474c authored Jan 09, 2016 by Peter Hurley Committed by Greg Kroah-Hartman Jan 28, 2016

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>

parent bee6741c

drivers/tty/tty_io.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -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);

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