linux-stable.git/drivers/tty/tty_ldisc.c, branch linux-3.13.y Linux kernel stable tree tty: Convert termios_mutex to termios_rwsem 2013-07-23T23:43:01+00:00 Peter Hurley peter@hurleysoftware.com 2013-06-15T13:14:23+00:00 6a1c0680cf3ba94356ecd58833e1540c93472a57 termios is commonly accessed unsafely (especially by N_TTY) because the existing mutex forces exclusive access. Convert existing usage. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
termios is commonly accessed unsafely (especially by N_TTY)
because the existing mutex forces exclusive access.
Convert existing usage.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty: Don't change receive_room for ioctl(TIOCSETD) 2013-07-23T23:42:59+00:00 Peter Hurley peter@hurleysoftware.com 2013-06-15T13:14:13+00:00 3b80df7ca7e2fec76be2eda304cc7e0eb90f911d tty_set_ldisc() is guaranteed exclusive use of the line discipline by tty_ldisc_lock_pair_timeout(); shutting off input by resetting receive_room is unnecessary. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
tty_set_ldisc() is guaranteed exclusive use of the line discipline
by tty_ldisc_lock_pair_timeout(); shutting off input by resetting
receive_room is unnecessary.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty: Clarify multiple-references comment in TIOCSETD ioctl 2013-07-23T23:38:35+00:00 Peter Hurley peter@hurleysoftware.com 2013-06-15T11:04:51+00:00 b0e95858238d95f32edf00ff4a0375165129d0c6 Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty: Fix hangup race with TIOCSETD ioctl 2013-07-23T23:38:35+00:00 Peter Hurley peter@hurleysoftware.com 2013-06-15T11:04:50+00:00 e97733ca677878d0ecf08af17f4661eb83e268bc The hangup may already have happened; check for that state also. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
The hangup may already have happened; check for that state also.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty: Clarify ldisc variable 2013-07-23T23:38:35+00:00 Peter Hurley peter@hurleysoftware.com 2013-06-15T11:04:49+00:00 9fbfa34c18b31978bf6bab26148f84d7a4b3ccea Rename o_ldisc to avoid confusion with the ldisc of the 'other' tty. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Rename o_ldisc to avoid confusion with the ldisc of the
'other' tty.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty: Replace ldisc locking with ldisc_sem 2013-07-23T23:38:34+00:00 Peter Hurley peter@hurleysoftware.com 2013-06-15T11:04:48+00:00 36697529b5bbe36911e39a6309e7a7c9250d280a Line discipline locking was performed with a combination of a mutex, a status bit, a count, and a waitqueue -- basically, a rw semaphore. Replace the existing combination with an ld_semaphore. Fixes: 1) the 'reference acquire after ldisc locked' bug 2) the over-complicated halt mechanism 3) lock order wrt. tty_lock() 4) dropping locks while changing ldisc 5) previously unidentified deadlock while locking ldisc from both linked ttys concurrently 6) previously unidentified recursive deadlocks Adds much-needed lockdep diagnostics. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Line discipline locking was performed with a combination of
a mutex, a status bit, a count, and a waitqueue -- basically,
a rw semaphore.

Replace the existing combination with an ld_semaphore.

Fixes:
 1) the 'reference acquire after ldisc locked' bug
 2) the over-complicated halt mechanism
 3) lock order wrt. tty_lock()
 4) dropping locks while changing ldisc
 5) previously unidentified deadlock while locking ldisc from
    both linked ttys concurrently
 6) previously unidentified recursive deadlocks

Adds much-needed lockdep diagnostics.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty: Add lock/unlock ldisc pair functions 2013-07-23T23:38:34+00:00 Peter Hurley peter@hurleysoftware.com 2013-06-15T11:04:47+00:00 d2c438905f9f718b3d9f5d89ce163fc22bd33995 Just as the tty pair must be locked in a stable sequence (ie, independent of which is consider the 'other' tty), so must the ldisc pair be locked in a stable sequence as well. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Just as the tty pair must be locked in a stable sequence
(ie, independent of which is consider the 'other' tty), so must
the ldisc pair be locked in a stable sequence as well.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty: Fix tty_ldisc_lock name collision 2013-07-23T23:38:34+00:00 Peter Hurley peter@hurleysoftware.com 2013-06-15T11:04:46+00:00 137084bbaddf4f6dde948ef3a14e18ba0754cc0d The file scope spinlock identifier, tty_ldisc_lock, will collide with the file scope lock function tty_ldisc_lock() so rename it. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
The file scope spinlock identifier, tty_ldisc_lock, will collide
with the file scope lock function tty_ldisc_lock() so rename it.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty: Remove redundant tty_wait_until_sent() 2013-03-18T23:48:42+00:00 Peter Hurley peter@hurleysoftware.com 2013-03-11T20:44:44+00:00 be3971166d93a401105952672dab2eac6542cb57 tty_ioctl() already waits until sent. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
tty_ioctl() already waits until sent.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty: Locate get/put ldisc functions together 2013-03-18T23:48:42+00:00 Peter Hurley peter@hurleysoftware.com 2013-03-11T20:44:43+00:00 734de249fbe2fbf594c30202a343f0772b6d18fe Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>