Commit Graph

83 Commits

Author SHA1 Message Date
Peter Hurley
52bce7f8d4 pty, n_tty: Simplify input processing on final close
When releasing one end of a pty pair, that end may just have written
to the other, which the input processing worker, flush_to_ldisc(), is
still working on but has not completed the copy to the other end's
read buffer. So input may not appear to be available to a waiting
reader but yet TTY_OTHER_CLOSED is now observed. The n_tty line
discipline has worked around this by waiting for input processing
to complete and then re-checking if input is available before
exiting with -EIO.

Since the tty/ldisc lock reordering, the wait for input processing
to complete can now occur during final close before setting
TTY_OTHER_CLOSED. In this way, a waiting reader is guaranteed to
see input available (if any) before observing TTY_OTHER_CLOSED.

Reviewed-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 18:50:42 -08:00
Peter Hurley
1bb954153a pty: Don't drop pty master tty lock to hangup slave
With the revised tty lock order and lockdep annotation, claiming
the pty slave lock is now safe while still holding the pty master lock.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 18:50:42 -08:00
Peter Hurley
2febdb632b tty: Preset lock subclass for nested tty locks
Eliminate the requirement of specifying the tty lock nesting at
lock time; instead, set the lock subclass for slave ptys at pty
install (normal ttys and master ptys use subclass 0).

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 18:50:42 -08:00
Peter Hurley
55199ea3bd pty: Always return -EIO if slave BSD pty opened first
Opening the slave BSD pty first already returns -EIO from the slave
pty_open(), which in turn causes the newly installed tty pair to be
released before returning from tty_open(). However, this can also
cause a parallel master BSD pty open to fail because the pty pair
destruction may already been taking place in tty_release().

Failing at driver->install() if the slave pty is opened first ensures
that a pty master open cannot fail, because the driver tables will
not have been updated so tty_driver_lookup_tty() won't find the
master pty (and attempt to "re-open" it).

In turn, this guarantees that any tty with a tty->count == 0 is
in final close (rather than never opened).

Reviewed-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 18:24:10 -08:00
Peter Hurley
4ed60fc257 pty: Hold ctrl_lock for packet mode updates
Updates to the packet mode enable require holding the ctrl_lock;
the serialization prevents corruption of adjacent fields.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Reviewed-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 16:34:36 -08:00
Peter Hurley
2622d73e51 pty: Fix packet mode setting race
Because pty_set_pktmode() does not claim the slave's ctrl_lock
to clear ->ctrl_status (to avoid unnecessary lock nesting),
pty_set_pktmode() may accidentally erase new ->ctrl_status updates.
For example,

CPU 0                             | CPU 1
pty_set_pktmode()                 | pty_start()
  spin_lock(master's ctrl_lock)   |
  tty->packet = 1                 |
                                  |   if (tty->link->packet)
                                  |     spin_lock(slave's ctrl_lock)
                                  |     tty->ctrl_status = TIOCPKT_START
  tty->link->ctrl_status = 0      |

Ensure the clear of ->ctrl_status occurs before packet mode is set
(and observable on another cpu).

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Reviewed-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 16:34:36 -08:00
Peter Hurley
54e8e5fcaa pty: Don't claim slave's ctrl_lock for master's packet mode
The slave's ctrl_lock serializes updates to the ctrl_status field
only, whereas the master's ctrl_lock serializes updates to the
packet mode enable (ie., the master does not have ctrl_status and
the slave does not have packet mode). Thus, claiming the slave's
ctrl_lock to access ->packet is useless.

Unlocked reads of ->packet are already smp-safe.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Reviewed-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 16:34:36 -08:00
Peter Hurley
6054c16e80 tty: Use spin_lock_irq() for ctrl_lock when interrupts enabled
Interrupts are enabled in the n_tty_read() loop, ioctl(TIOCPKT)
and pty driver flush_buffer() routine; no need to save and restore
local interrupt state.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Reviewed-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 16:34:36 -08:00
Peter Hurley
4d8c1dff6a pty: Use spin_lock_irq() for pty_set_termios()
The tty driver's set_termios() method is called with interrupts
enabled; there is no need to save and restore the local interrupt state.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Reviewed-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 16:34:36 -08:00
Peter Hurley
dbfcd851a9 tty: Move pty-specific set_termios() handling to pty driver
Packet mode is unique to the pty driver; move the packet mode state
change code from the generic tty ioctl handler to the pty driver.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Reviewed-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 16:34:36 -08:00
Peter Hurley
6460fbbf47 tty: WARN for attempted set_termios() of pty master
The pty master's termios should never be set; currently, all code
paths which call the driver's set_termios() method ensure that the
pty slave's termios is being set.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Reviewed-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 16:34:36 -08:00
Peter Hurley
5b23954220 tty: Replace open-coded tty_get_pgrp()
Replace open-coded instances of tty_get_pgrp().

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Reviewed-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 16:26:13 -08:00
Peter Hurley
01adc80706 tty: Move packet mode flow control notifications to pty driver
When a master pty is set to packet mode, flow control changes to
the slave pty cause notifications to the master pty via reads and
polls. However, these tests are occurring for all ttys, not
just ptys.

Implement flow control packet mode notifications in the pty driver.
Only the slave side implements the flow control handlers since
packet mode is asymmetric; the master pty receives notifications
for slave-side changes, but not vice versa.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-23 21:19:35 -07:00
Rasmus Villemoes
07584d4a35 drivers: tty: Fix use-after-free in pty_common_install
In 2c964a2f "drivers: tty: Merge alloc_tty_struct and
initialize_tty_struct", I messed up the refactorization of
pty_common_install, causing use-after-free and NULL pointer derefs on
various error paths. This should fix it.

Reported-by: Julia Lawall <julia.lawall@lip6.fr>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-07-12 17:21:47 -07:00
Rasmus Villemoes
2c964a2f41 drivers: tty: Merge alloc_tty_struct and initialize_tty_struct
The two functions alloc_tty_struct and initialize_tty_struct are
always called together. Merge them into alloc_tty_struct, updating its
prototype and the only two callers of these functions.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-07-11 17:54:28 -07:00
Peter Hurley
dee4a0be69 tty: Fix lock order in tty_do_resize()
Commits 6a1c0680cf and
9356b535fc, respectively
  'tty: Convert termios_mutex to termios_rwsem' and
  'n_tty: Access termios values safely'
introduced a circular lock dependency with console_lock and
termios_rwsem.

The lockdep report [1] shows that n_tty_write() will attempt
to claim console_lock while holding the termios_rwsem, whereas
tty_do_resize() may already hold the console_lock while
claiming the termios_rwsem.

Since n_tty_write() and tty_do_resize() do not contend
over the same data -- the tty->winsize structure -- correct
the lock dependency by introducing a new lock which
specifically serializes access to tty->winsize only.

[1] Lockdep report

======================================================
[ INFO: possible circular locking dependency detected ]
3.10.0-0+tip-xeon+lockdep #0+tip Not tainted
-------------------------------------------------------
modprobe/277 is trying to acquire lock:
 (&tty->termios_rwsem){++++..}, at: [<ffffffff81452656>] tty_do_resize+0x36/0xe0

but task is already holding lock:
 ((fb_notifier_list).rwsem){.+.+.+}, at: [<ffffffff8107aac6>] __blocking_notifier_call_chain+0x56/0xc0

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #2 ((fb_notifier_list).rwsem){.+.+.+}:
       [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0
       [<ffffffff8175b797>] down_read+0x47/0x5c
       [<ffffffff8107aac6>] __blocking_notifier_call_chain+0x56/0xc0
       [<ffffffff8107ab46>] blocking_notifier_call_chain+0x16/0x20
       [<ffffffff813d7c0b>] fb_notifier_call_chain+0x1b/0x20
       [<ffffffff813d95b2>] register_framebuffer+0x1e2/0x320
       [<ffffffffa01043e1>] drm_fb_helper_initial_config+0x371/0x540 [drm_kms_helper]
       [<ffffffffa01bcb05>] nouveau_fbcon_init+0x105/0x140 [nouveau]
       [<ffffffffa01ad0af>] nouveau_drm_load+0x43f/0x610 [nouveau]
       [<ffffffffa008a79e>] drm_get_pci_dev+0x17e/0x2a0 [drm]
       [<ffffffffa01ad4da>] nouveau_drm_probe+0x25a/0x2a0 [nouveau]
       [<ffffffff813b13db>] local_pci_probe+0x4b/0x80
       [<ffffffff813b1701>] pci_device_probe+0x111/0x120
       [<ffffffff814977eb>] driver_probe_device+0x8b/0x3a0
       [<ffffffff81497bab>] __driver_attach+0xab/0xb0
       [<ffffffff814956ad>] bus_for_each_dev+0x5d/0xa0
       [<ffffffff814971fe>] driver_attach+0x1e/0x20
       [<ffffffff81496cc1>] bus_add_driver+0x111/0x290
       [<ffffffff814982b7>] driver_register+0x77/0x170
       [<ffffffff813b0454>] __pci_register_driver+0x64/0x70
       [<ffffffffa008a9da>] drm_pci_init+0x11a/0x130 [drm]
       [<ffffffffa022a04d>] nouveau_drm_init+0x4d/0x1000 [nouveau]
       [<ffffffff810002ea>] do_one_initcall+0xea/0x1a0
       [<ffffffff810c54cb>] load_module+0x123b/0x1bf0
       [<ffffffff810c5f57>] SyS_init_module+0xd7/0x120
       [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b

-> #1 (console_lock){+.+.+.}:
       [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0
       [<ffffffff810430a7>] console_lock+0x77/0x80
       [<ffffffff8146b2a1>] con_flush_chars+0x31/0x50
       [<ffffffff8145780c>] n_tty_write+0x1ec/0x4d0
       [<ffffffff814541b9>] tty_write+0x159/0x2e0
       [<ffffffff814543f5>] redirected_tty_write+0xb5/0xc0
       [<ffffffff811ab9d5>] vfs_write+0xc5/0x1f0
       [<ffffffff811abec5>] SyS_write+0x55/0xa0
       [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b

-> #0 (&tty->termios_rwsem){++++..}:
       [<ffffffff810b65c3>] __lock_acquire+0x1c43/0x1d30
       [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0
       [<ffffffff8175b724>] down_write+0x44/0x70
       [<ffffffff81452656>] tty_do_resize+0x36/0xe0
       [<ffffffff8146c841>] vc_do_resize+0x3e1/0x4c0
       [<ffffffff8146c99f>] vc_resize+0x1f/0x30
       [<ffffffff813e4535>] fbcon_init+0x385/0x5a0
       [<ffffffff8146a4bc>] visual_init+0xbc/0x120
       [<ffffffff8146cd13>] do_bind_con_driver+0x163/0x320
       [<ffffffff8146cfa1>] do_take_over_console+0x61/0x70
       [<ffffffff813e2b93>] do_fbcon_takeover+0x63/0xc0
       [<ffffffff813e67a5>] fbcon_event_notify+0x715/0x820
       [<ffffffff81762f9d>] notifier_call_chain+0x5d/0x110
       [<ffffffff8107aadc>] __blocking_notifier_call_chain+0x6c/0xc0
       [<ffffffff8107ab46>] blocking_notifier_call_chain+0x16/0x20
       [<ffffffff813d7c0b>] fb_notifier_call_chain+0x1b/0x20
       [<ffffffff813d95b2>] register_framebuffer+0x1e2/0x320
       [<ffffffffa01043e1>] drm_fb_helper_initial_config+0x371/0x540 [drm_kms_helper]
       [<ffffffffa01bcb05>] nouveau_fbcon_init+0x105/0x140 [nouveau]
       [<ffffffffa01ad0af>] nouveau_drm_load+0x43f/0x610 [nouveau]
       [<ffffffffa008a79e>] drm_get_pci_dev+0x17e/0x2a0 [drm]
       [<ffffffffa01ad4da>] nouveau_drm_probe+0x25a/0x2a0 [nouveau]
       [<ffffffff813b13db>] local_pci_probe+0x4b/0x80
       [<ffffffff813b1701>] pci_device_probe+0x111/0x120
       [<ffffffff814977eb>] driver_probe_device+0x8b/0x3a0
       [<ffffffff81497bab>] __driver_attach+0xab/0xb0
       [<ffffffff814956ad>] bus_for_each_dev+0x5d/0xa0
       [<ffffffff814971fe>] driver_attach+0x1e/0x20
       [<ffffffff81496cc1>] bus_add_driver+0x111/0x290
       [<ffffffff814982b7>] driver_register+0x77/0x170
       [<ffffffff813b0454>] __pci_register_driver+0x64/0x70
       [<ffffffffa008a9da>] drm_pci_init+0x11a/0x130 [drm]
       [<ffffffffa022a04d>] nouveau_drm_init+0x4d/0x1000 [nouveau]
       [<ffffffff810002ea>] do_one_initcall+0xea/0x1a0
       [<ffffffff810c54cb>] load_module+0x123b/0x1bf0
       [<ffffffff810c5f57>] SyS_init_module+0xd7/0x120
       [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b

other info that might help us debug this:

Chain exists of:
  &tty->termios_rwsem --> console_lock --> (fb_notifier_list).rwsem

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock((fb_notifier_list).rwsem);
                               lock(console_lock);
                               lock((fb_notifier_list).rwsem);
  lock(&tty->termios_rwsem);

 *** DEADLOCK ***

7 locks held by modprobe/277:
 #0:  (&__lockdep_no_validate__){......}, at: [<ffffffff81497b5b>] __driver_attach+0x5b/0xb0
 #1:  (&__lockdep_no_validate__){......}, at: [<ffffffff81497b69>] __driver_attach+0x69/0xb0
 #2:  (drm_global_mutex){+.+.+.}, at: [<ffffffffa008a6dd>] drm_get_pci_dev+0xbd/0x2a0 [drm]
 #3:  (registration_lock){+.+.+.}, at: [<ffffffff813d93f5>] register_framebuffer+0x25/0x320
 #4:  (&fb_info->lock){+.+.+.}, at: [<ffffffff813d8116>] lock_fb_info+0x26/0x60
 #5:  (console_lock){+.+.+.}, at: [<ffffffff813d95a4>] register_framebuffer+0x1d4/0x320
 #6:  ((fb_notifier_list).rwsem){.+.+.+}, at: [<ffffffff8107aac6>] __blocking_notifier_call_chain+0x56/0xc0

stack backtrace:
CPU: 0 PID: 277 Comm: modprobe Not tainted 3.10.0-0+tip-xeon+lockdep #0+tip
Hardware name: Dell Inc. Precision WorkStation T5400  /0RW203, BIOS A11 04/30/2012
 ffffffff8213e5e0 ffff8802aa2fb298 ffffffff81755f19 ffff8802aa2fb2e8
 ffffffff8174f506 ffff8802aa2fa000 ffff8802aa2fb378 ffff8802aa2ea8e8
 ffff8802aa2ea910 ffff8802aa2ea8e8 0000000000000006 0000000000000007
Call Trace:
 [<ffffffff81755f19>] dump_stack+0x19/0x1b
 [<ffffffff8174f506>] print_circular_bug+0x1fb/0x20c
 [<ffffffff810b65c3>] __lock_acquire+0x1c43/0x1d30
 [<ffffffff810b775e>] ? mark_held_locks+0xae/0x120
 [<ffffffff810b78d5>] ? trace_hardirqs_on_caller+0x105/0x1d0
 [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0
 [<ffffffff81452656>] ? tty_do_resize+0x36/0xe0
 [<ffffffff8175b724>] down_write+0x44/0x70
 [<ffffffff81452656>] ? tty_do_resize+0x36/0xe0
 [<ffffffff81452656>] tty_do_resize+0x36/0xe0
 [<ffffffff8146c841>] vc_do_resize+0x3e1/0x4c0
 [<ffffffff8146c99f>] vc_resize+0x1f/0x30
 [<ffffffff813e4535>] fbcon_init+0x385/0x5a0
 [<ffffffff8146a4bc>] visual_init+0xbc/0x120
 [<ffffffff8146cd13>] do_bind_con_driver+0x163/0x320
 [<ffffffff8146cfa1>] do_take_over_console+0x61/0x70
 [<ffffffff813e2b93>] do_fbcon_takeover+0x63/0xc0
 [<ffffffff813e67a5>] fbcon_event_notify+0x715/0x820
 [<ffffffff81762f9d>] notifier_call_chain+0x5d/0x110
 [<ffffffff8107aadc>] __blocking_notifier_call_chain+0x6c/0xc0
 [<ffffffff8107ab46>] blocking_notifier_call_chain+0x16/0x20
 [<ffffffff813d7c0b>] fb_notifier_call_chain+0x1b/0x20
 [<ffffffff813d95b2>] register_framebuffer+0x1e2/0x320
 [<ffffffffa01043e1>] drm_fb_helper_initial_config+0x371/0x540 [drm_kms_helper]
 [<ffffffff8173cbcb>] ? kmemleak_alloc+0x5b/0xc0
 [<ffffffff81198874>] ? kmem_cache_alloc_trace+0x104/0x290
 [<ffffffffa01035e1>] ? drm_fb_helper_single_add_all_connectors+0x81/0xf0 [drm_kms_helper]
 [<ffffffffa01bcb05>] nouveau_fbcon_init+0x105/0x140 [nouveau]
 [<ffffffffa01ad0af>] nouveau_drm_load+0x43f/0x610 [nouveau]
 [<ffffffffa008a79e>] drm_get_pci_dev+0x17e/0x2a0 [drm]
 [<ffffffffa01ad4da>] nouveau_drm_probe+0x25a/0x2a0 [nouveau]
 [<ffffffff8175f162>] ? _raw_spin_unlock_irqrestore+0x42/0x80
 [<ffffffff813b13db>] local_pci_probe+0x4b/0x80
 [<ffffffff813b1701>] pci_device_probe+0x111/0x120
 [<ffffffff814977eb>] driver_probe_device+0x8b/0x3a0
 [<ffffffff81497bab>] __driver_attach+0xab/0xb0
 [<ffffffff81497b00>] ? driver_probe_device+0x3a0/0x3a0
 [<ffffffff814956ad>] bus_for_each_dev+0x5d/0xa0
 [<ffffffff814971fe>] driver_attach+0x1e/0x20
 [<ffffffff81496cc1>] bus_add_driver+0x111/0x290
 [<ffffffffa022a000>] ? 0xffffffffa0229fff
 [<ffffffff814982b7>] driver_register+0x77/0x170
 [<ffffffffa022a000>] ? 0xffffffffa0229fff
 [<ffffffff813b0454>] __pci_register_driver+0x64/0x70
 [<ffffffffa008a9da>] drm_pci_init+0x11a/0x130 [drm]
 [<ffffffffa022a000>] ? 0xffffffffa0229fff
 [<ffffffffa022a000>] ? 0xffffffffa0229fff
 [<ffffffffa022a04d>] nouveau_drm_init+0x4d/0x1000 [nouveau]
 [<ffffffff810002ea>] do_one_initcall+0xea/0x1a0
 [<ffffffff810c54cb>] load_module+0x123b/0x1bf0
 [<ffffffff81399a50>] ? ddebug_proc_open+0xb0/0xb0
 [<ffffffff813855ae>] ? trace_hardirqs_on_thunk+0x3a/0x3f
 [<ffffffff810c5f57>] SyS_init_module+0xd7/0x120
 [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-07-24 15:12:53 -07:00
Peter Hurley
5ede52538e tty: Remove extra wakeup from pty write() path
Acquiring the write_wait queue spin lock now accounts for the largest
slice of cpu time on the tty write path. Two factors contribute to
this situation; a overly-pessimistic line discipline write loop which
_always_ sets up a wait loop even if i/o will immediately succeed, and
on ptys, a wakeup storm from reads and writes.

Writer wakeup does not need to be performed by the pty driver.
Firstly, since the actual i/o is performed within the write, the
line discipline write loop will continue while space remains in
the flip buffers. Secondly, when space becomes avail in the
line discipline receive buffer (and thus also in the flip buffers),
the pty unthrottle re-wakes the writer (non-flow-controlled line
disciplines unconditionally unthrottle the driver when data is
received). Thus, existing in-kernel i/o is guaranteed to advance.
Finally, writer wakeup occurs at the conclusion of the line discipline
write (in tty_write_unlock()). This guarantees that any user-space write
waiters are woken to continue additional i/o.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-07-24 09:29:56 -07:00
Peter Hurley
7bfe0b7116 tty: Track flip buffer memory limit atomically
Lockless flip buffers require atomically updating the bytes-in-use
watermark.

The pty driver also peeks at the watermark value to limit
memory consumption to a much lower value than the default; query
the watermark with new fn, tty_buffer_space_avail().

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-07-23 16:47:08 -07:00
Peter Hurley
6a1c0680cf tty: Convert termios_mutex to termios_rwsem
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>
2013-07-23 16:43:01 -07:00
Peter Hurley
7c61c3d8f4 tty: Fix transient pty write() EIO
Commit 699390354d
('pty: Ignore slave pty close() if never successfully opened')
introduced a bug with ptys whereby a write() in parallel with an
open() on an existing pty could mistakenly indicate an I/O error.

Only indicate an I/O error if the condition on open() actually exists.

Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Tested-by: Mikael Pettersson <mikpe@it.uu.se>
Cc: stable <stable@vger.kernel.org> # 3.9
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-06-17 12:37:29 -07:00
Linus Torvalds
b0b885657b tty: fix up atime/mtime mess, take three
We first tried to avoid updating atime/mtime entirely (commit
b0de59b573: "TTY: do not update atime/mtime on read/write"), and then
limited it to only update it occasionally (commit 37b7f3c765: "TTY:
fix atime/mtime regression"), but it turns out that this was both
insufficient and overkill.

It was insufficient because we let people attach to the shared ptmx node
to see activity without even reading atime/mtime, and it was overkill
because the "only once a minute" means that you can't really tell an
idle person from an active one with 'w'.

So this tries to fix the problem properly.  It marks the shared ptmx
node as un-notifiable, and it lowers the "only once a minute" to a few
seconds instead - still long enough that you can't time individual
keystrokes, but short enough that you can tell whether somebody is
active or not.

Reported-by: Simon Kirby <sim@hostway.ca>
Acked-by: Jiri Slaby <jslaby@suse.cz>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-05-01 07:32:21 -07:00
Jiri Slaby
f4b208eb91 TTY: pty, fix compilation warning
When CONFIG_UNIX98_PTYS is unset, we see this warning in pty:
  drivers/tty/pty.c:409:13: warning: ‘pty_unix98_shutdown’ defined but not used

Fix that by moving the function to a section which depends on that
config.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Reported-by: Toralf Foerster <toralf.foerster@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-04-15 11:02:54 -07:00
Peter Hurley
19ffd68f81 pty: Remove redundant itty reset
port->itty has already been reset by release_tty() before
pty_cleanup() is called.

Call stack:
release_tty()
  tty_kref_put()
    queue_release_one_tty()
      release_one_tty() : workqueue
        tty->ops->cleanup()
          pty_cleanup()

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-15 13:00:48 -07:00
Peter Hurley
80cace7256 pty: Ignore slave open count for master pty open
Multiple slave pty opens may be performed in parallel with the
master open. Of course, all the slave opens will fail because the
master pty is still locked but during this time the slave pty
count will be artificially greater than 1. This is should not
cause the master pty open to fail.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-02-04 15:40:29 -08:00
Peter Hurley
699390354d pty: Ignore slave pty close() if never successfully opened
If the master and slave ptys are opened in parallel, the slave open
fails because the pty is still locked. This is as designed.
However, pty_close() is still called for the slave pty which sets
TTY_OTHER_CLOSED in the master pty. This can cause the master open
to fail as well.

Use a common pattern in other tty drivers by setting TTY_IO_ERROR
until the open is successful and only closing the pty if not set.

Note: the master pty always closes regardless of whether the open
was successful, so that proper cleanup can occur.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-02-04 15:40:28 -08:00
Peter Hurley
7acf6cd80b pty: Fix BUG()s when ptmx_open() errors out
If pmtx_open() fails to get a slave inode or fails the pty_open(),
the tty is released as part of the error cleanup. As evidenced by the
first BUG stacktrace below, pty_close() assumes that the linked pty has
a valid, initialized inode* stored in driver_data.

Also, as evidenced by the second BUG stacktrace below, pty_unix98_shutdown()
assumes that the master pty's driver_data has been initialized.

1) Fix the invalid assumption in pty_close().
2) Initialize driver_data immediately so proper devpts fs cleanup occurs.

Fixes this BUG:

[  815.868844] BUG: unable to handle kernel NULL pointer dereference at 0000000000000028
[  815.869018] IP: [<ffffffff81207bcc>] devpts_pty_kill+0x1c/0xa0
[  815.869190] PGD 7c775067 PUD 79deb067 PMD 0
[  815.869315] Oops: 0000 [#1] PREEMPT SMP
[  815.869443] Modules linked in: kvm_intel kvm snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_seq_midi microcode snd_rawmidi psmouse serio_raw snd_seq_midi_event snd_seq snd_timer$
[  815.870025] CPU 0
[  815.870143] Pid: 27819, comm: stress_test_tty Tainted: G        W    3.8.0-next-20130125+ttypatch-2-xeon #2 Bochs Bochs
[  815.870386] RIP: 0010:[<ffffffff81207bcc>]  [<ffffffff81207bcc>] devpts_pty_kill+0x1c/0xa0
[  815.870540] RSP: 0018:ffff88007d3e1ac8  EFLAGS: 00010282
[  815.870661] RAX: ffff880079c20800 RBX: 0000000000000000 RCX: 0000000000000000
[  815.870804] RDX: ffff880079c209a8 RSI: 0000000000000286 RDI: 0000000000000000
[  815.870933] RBP: ffff88007d3e1ae8 R08: 0000000000000000 R09: 0000000000000000
[  815.871078] R10: 0000000000000000 R11: 0000000000000001 R12: ffff88007bfb7e00
[  815.871209] R13: 0000000000000005 R14: ffff880079c20c00 R15: ffff880079c20c00
[  815.871343] FS:  00007f2e86206700(0000) GS:ffff88007fc00000(0000) knlGS:0000000000000000
[  815.871495] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[  815.871617] CR2: 0000000000000028 CR3: 000000007ae56000 CR4: 00000000000006f0
[  815.871752] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  815.871902] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[  815.872012] Process stress_test_tty (pid: 27819, threadinfo ffff88007d3e0000, task ffff88007c874530)
[  815.872012] Stack:
[  815.872012]  ffff88007bfb7e00 ffff880079c20c00 ffff88007bfb7e00 0000000000000005
[  815.872012]  ffff88007d3e1b08 ffffffff81417be7 ffff88007caa9bd8 ffff880079c20800
[  815.872012]  ffff88007d3e1bc8 ffffffff8140e5f8 0000000000000000 0000000000000000
[  815.872012] Call Trace:
[  815.872012]  [<ffffffff81417be7>] pty_close+0x157/0x170
[  815.872012]  [<ffffffff8140e5f8>] tty_release+0x138/0x580
[  815.872012]  [<ffffffff816d29f3>] ? _raw_spin_lock+0x23/0x30
[  815.872012]  [<ffffffff816d267a>] ? _raw_spin_unlock+0x1a/0x40
[  815.872012]  [<ffffffff816d0178>] ? __mutex_unlock_slowpath+0x48/0x60
[  815.872012]  [<ffffffff81417dff>] ptmx_open+0x11f/0x180
[  815.872012]  [<ffffffff8119394b>] chrdev_open+0x9b/0x1c0
[  815.872012]  [<ffffffff8118d643>] do_dentry_open+0x203/0x290
[  815.872012]  [<ffffffff811938b0>] ? cdev_put+0x30/0x30
[  815.872012]  [<ffffffff8118d705>] finish_open+0x35/0x50
[  815.872012]  [<ffffffff8119dcce>] do_last+0x6fe/0xe90
[  815.872012]  [<ffffffff8119a7af>] ? link_path_walk+0x7f/0x880
[  815.872012]  [<ffffffff810909d5>] ? cpuacct_charge+0x75/0x80
[  815.872012]  [<ffffffff8119e51c>] path_openat+0xbc/0x4e0
[  815.872012]  [<ffffffff816d0fd0>] ? __schedule+0x400/0x7f0
[  815.872012]  [<ffffffff8140e956>] ? tty_release+0x496/0x580
[  815.872012]  [<ffffffff8119ec11>] do_filp_open+0x41/0xa0
[  815.872012]  [<ffffffff816d267a>] ? _raw_spin_unlock+0x1a/0x40
[  815.872012]  [<ffffffff811abe39>] ? __alloc_fd+0xe9/0x140
[  815.872012]  [<ffffffff8118ea44>] do_sys_open+0xf4/0x1e0
[  815.872012]  [<ffffffff8118eb51>] sys_open+0x21/0x30
[  815.872012]  [<ffffffff816da499>] system_call_fastpath+0x16/0x1b
[  815.872012] Code: 0f 1f 80 00 00 00 00 45 31 e4 eb d7 0f 0b 90 0f 1f 44 00 00 55 48 89 e5 48 83 ec 20 48 89 5d e8 48 89 fb 4c 89 65 f0 4c 89 6d f8 <48> 8b 47 28 48 81 78 58 d1 1c 0$
[  815.872012] RIP  [<ffffffff81207bcc>] devpts_pty_kill+0x1c/0xa0
[  815.872012]  RSP <ffff88007d3e1ac8>
[  815.872012] CR2: 0000000000000028
[  815.897036] ---[ end trace eadf50b7f34e47d5 ]---

Fixes this BUG also:

[  608.366836] BUG: unable to handle kernel NULL pointer dereference at 0000000000000028
[  608.366948] IP: [<ffffffff812078d8>] devpts_kill_index+0x18/0x70
[  608.367050] PGD 7c75b067 PUD 7b919067 PMD 0
[  608.367135] Oops: 0000 [#1] PREEMPT SMP
[  608.367201] Modules linked in: kvm_intel kvm snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_seq_midi snd_rawmidi snd_seq_midi_event microcode snd_seq psmouse snd_timer snd_seq_device serio_raw snd mac_hid soundcore snd_page_alloc rfcomm virtio_balloon parport_pc bnep bluetooth ppdev i2c_piix4 lp parport floppy
[  608.367617] CPU 2
[  608.367669] Pid: 1918, comm: stress_test_tty Tainted: G        W    3.8.0-next-20130125+ttypatch-2-xeon #2 Bochs Bochs
[  608.367796] RIP: 0010:[<ffffffff812078d8>]  [<ffffffff812078d8>] devpts_kill_index+0x18/0x70
[  608.367885] RSP: 0018:ffff88007ae41a88  EFLAGS: 00010286
[  608.367951] RAX: ffffffff81417e80 RBX: ffff880036472400 RCX: 0000000180400028
[  608.368010] RDX: ffff880036470004 RSI: 0000000000000004 RDI: 0000000000000000
[  608.368010] RBP: ffff88007ae41a98 R08: 0000000000000000 R09: 0000000000000001
[  608.368010] R10: ffffea0001f22e40 R11: ffffffff814151d5 R12: 0000000000000004
[  608.368010] R13: ffff880036470000 R14: 0000000000000004 R15: ffff880036472400
[  608.368010] FS:  00007ff7a5268700(0000) GS:ffff88007fd00000(0000) knlGS:0000000000000000
[  608.368010] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[  608.368010] CR2: 0000000000000028 CR3: 000000007a0fd000 CR4: 00000000000006e0
[  608.368010] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  608.368010] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[  608.368010] Process stress_test_tty (pid: 1918, threadinfo ffff88007ae40000, task ffff88003688dc40)
[  608.368010] Stack:
[  608.368010]  ffff880036472400 0000000000000001 ffff88007ae41aa8 ffffffff81417e98
[  608.368010]  ffff88007ae41ac8 ffffffff8140c42b ffff88007ac73100 ffff88007ac73100
[  608.368010]  ffff88007ae41b98 ffffffff8140ead5 ffff88007ae41b38 ffff88007ca40e40
[  608.368010] Call Trace:
[  608.368010]  [<ffffffff81417e98>] pty_unix98_shutdown+0x18/0x20
[  608.368010]  [<ffffffff8140c42b>] release_tty+0x3b/0xe0
[  608.368010]  [<ffffffff8140ead5>] __tty_release+0x575/0x5d0
[  608.368010]  [<ffffffff816d2c63>] ? _raw_spin_lock+0x23/0x30
[  608.368010]  [<ffffffff816d28ea>] ? _raw_spin_unlock+0x1a/0x40
[  608.368010]  [<ffffffff816d03e8>] ? __mutex_unlock_slowpath+0x48/0x60
[  608.368010]  [<ffffffff8140ef79>] tty_open+0x449/0x5f0
[  608.368010]  [<ffffffff8119394b>] chrdev_open+0x9b/0x1c0
[  608.368010]  [<ffffffff8118d643>] do_dentry_open+0x203/0x290
[  608.368010]  [<ffffffff811938b0>] ? cdev_put+0x30/0x30
[  608.368010]  [<ffffffff8118d705>] finish_open+0x35/0x50
[  608.368010]  [<ffffffff8119dcce>] do_last+0x6fe/0xe90
[  608.368010]  [<ffffffff8119a7af>] ? link_path_walk+0x7f/0x880
[  608.368010]  [<ffffffff8119e51c>] path_openat+0xbc/0x4e0
[  608.368010]  [<ffffffff8119ec11>] do_filp_open+0x41/0xa0
[  608.368010]  [<ffffffff816d28ea>] ? _raw_spin_unlock+0x1a/0x40
[  608.368010]  [<ffffffff811abe39>] ? __alloc_fd+0xe9/0x140
[  608.368010]  [<ffffffff8118ea44>] do_sys_open+0xf4/0x1e0
[  608.368010]  [<ffffffff816d2c63>] ? _raw_spin_lock+0x23/0x30
[  608.368010]  [<ffffffff8118eb51>] sys_open+0x21/0x30
[  608.368010]  [<ffffffff816da719>] system_call_fastpath+0x16/0x1b
[  608.368010] Code: ec 48 83 c4 10 5b 41 5c 5d c3 66 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 48 83 ec 10 4c 89 65 f8 41 89 f4 48 89 5d f0 <48> 8b 47 28 48 81 78 58 d1 1c 00 00 74 0b 48 8b 05 4b 66 cf 00
[  608.368010] RIP  [<ffffffff812078d8>] devpts_kill_index+0x18/0x70
[  608.368010]  RSP <ffff88007ae41a88>
[  608.368010] CR2: 0000000000000028
[  608.394153] ---[ end trace afe83b0fb5fbda93 ]---

Reported-by: Ilya Zykov <ilya@ilyx.ru>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-02-04 15:40:28 -08:00
Greg Kroah-Hartman
9f9cba810f Merge 3.8-rc5 into tty-next
This resolves a number of tty driver merge issues found in linux-next

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-01-25 13:27:36 -08:00
Jiri Slaby
ded2f295a3 pty: return EINVAL for TIOCGPTN for BSD ptys
Commit bbb63c514a (drivers:tty:fix up
ENOIOCTLCMD error handling) changed the default return value from tty
ioctl to be ENOTTY and not EINVAL. This is appropriate.

But in case of TIOCGPTN for the old BSD ptys glibc started failing
because it expects EINVAL to be returned. Only then it continues to
obtain the pts name the other way around.

So fix this case by explicit return of EINVAL in this case.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Reported-by: Florian Westphal <fw@strlen.de>
Cc: Alan Cox <alan@linux.intel.com>
Cc: stable <stable@vger.kernel.org> # 3.7+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-01-17 13:56:57 -08:00
Jiri Slaby
b81273a132 TTY: do not reset master's packet mode
Now that login from util-linux is forced to drop all references to a
TTY which it wants to hangup (to reach reference count 1) we are
seeing issues with telnet. When login closes its last reference to the
slave PTY, it also resets packet mode on the *master* side. And we
have a race here.

What telnet does is fork+exec of `login'. Then there are two
scenarios:
* `login' closes the slave TTY and resets thus master's packet mode,
  but even now telnet properly sets the mode, or
* `telnetd' sets packet mode on the master, `login' closes the slave
  TTY and resets master's packet mode.

The former case is OK. However the latter happens in much more cases,
by the order of magnitude to be precise. So when one tries to login to
such a messed telnet setup, they see the following:
inux login:
            ogin incorrect

Note the missing first letters -- telnet thinks it is still in the
packet mode, so when it receives "linux login" from `login', it
considers "l" as the type of the packet and strips it.

SuS does not mention how the implementation should behave. Both BSDs I
checked (Free and Net) do not reset the flag upon the last close.

By this I am resurrecting an old bug, see References. We are hitting
it regularly now, i.e. with updated util-linux, ergo login.

Here, I am changing a behavior introduced back in 2.1 times. It would
better have a long time testing before goes upstream.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Mauro Carvalho Chehab <mchehab@redhat.com>
Cc: Bryan Mason <bmason@redhat.com>
References: https://lkml.org/lkml/2009/11/11/223
References: https://bugzilla.redhat.com/show_bug.cgi?id=504703
References: https://bugzilla.novell.com/show_bug.cgi?id=797042
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-01-15 22:49:36 -08:00
Cong Ding
b9f8033f28 tty: cleanup checkpatch warning in pty.c
spaces are used for indent in 3 places of tty/pty.c, we change it to tab.

Signed-off-by: Cong Ding <dinggnu@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-01-15 22:49:36 -08:00
Cong Ding
82f8c35f86 tty: cleanup the panic message
the "\n" in panic message is excess, so we remove it in tty/pty.c as what it
is used in other places.

Signed-off-by: Cong Ding <dinggnu@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-01-15 22:49:36 -08:00
Jiri Slaby
2e124b4a39 TTY: switch tty_flip_buffer_push
Now, we start converting tty buffer functions to actually use
tty_port. This will allow us to get rid of the need of tty in many
call sites. Only tty_port will needed and hence no more
tty_port_tty_get in those paths.

Now, the one where most of tty_port_tty_get gets removed:
tty_flip_buffer_push.

IOW we also closed all the races in drivers not using tty_port_tty_get
at all yet.

Also we move tty_flip_buffer_push declaration from include/linux/tty.h
to include/linux/tty_flip.h to all others while we are changing it
anyway.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-01-15 22:30:15 -08:00
Jiri Slaby
05c7cd3990 TTY: switch tty_insert_flip_string
Now, we start converting tty buffer functions to actually use
tty_port. This will allow us to get rid of the need of tty in many
call sites. Only tty_port will needed and hence no more
tty_port_tty_get in those paths.

tty_insert_flip_string this time.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-01-15 22:22:35 -08:00
Josh Triplett
159a8e92fd pty: Mark pty_resize static
Nothing outside of drivers/tty/pty.c references pty_resize.

Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-11-21 15:43:26 -08:00
Jiri Slaby
81c79838ca TTY: pty, fix tty buffers leak
After commit "TTY: move tty buffers to tty_port", the tty buffers are
not freed in some drivers. This is because tty_port_destructor is not
called whenever a tty_port is freed. This was an assumption I counted
with but was unfortunately untrue. So fix the drivers to fulfil this
assumption.

PTY is one of those, here we just need to use tty_port_put instead of
kfree. (Assuming tty_port_destructor does not need port->ops to be set
which we change here too.)

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-11-15 17:18:55 -08:00
Cyrill Gorcunov
84fd7bdf12 tty: Add get- ioctls to fetch tty status v3
For checkpoint/restore we need to know if tty has
exclusive or packet mode set, as well as if pty
is currently locked. Just to be able to restore
this characteristics.

For this sake the following ioctl codes are introduced

 - TIOCGPKT to get packet mode state
 - TIOCGPTLCK to get Pty locked state
 - TIOCGEXCL to get Exclusive mode state

Note this ioctls are a bit unsafe in terms of data
obtained consistency. The tty characteristics might
be changed right after ioctl complete. Keep it in
mind and use this ioctl carefully.

v2:
 - Use TIOC prefix for ioctl codes (by jslaby@)

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
CC: Alan Cox <alan@lxorguk.ukuu.org.uk>
CC: "H. Peter Anvin" <hpa@zytor.com>
CC: Pavel Emelyanov <xemul@parallels.com>
CC: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-10-25 12:07:18 -07:00
Cyrill Gorcunov
06026d911c tty: pty - Move TIOCPKT handling into pty.c
Since this ioctl is for pty devices only move it to pty.c.

v2:
 - drop PTY_TYPE_MASTER test since it's master peer
   ioctl anyway (by jslaby@)

Suggested-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
CC: "H. Peter Anvin" <hpa@zytor.com>
CC: Pavel Emelyanov <xemul@parallels.com>
CC: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-10-25 12:07:18 -07:00
Jiri Slaby
ecbbfd44a0 TTY: move tty buffers to tty_port
So this is it. The big step why we did all the work over the past
kernel releases. Now everything is prepared, so nothing protects us
from doing that big step.

           |  |            \  \ nnnn/^l      |  |
           |  |             \  /     /       |  |
           |  '-,.__   =>    \/   ,-`    =>  |  '-,.__
           | O __.´´)        (  .`           | O __.´´)
            ~~~   ~~          ``              ~~~   ~~
The buffers are now in the tty_port structure and we can start
teaching the buffer helpers (insert char/string, flip etc.) to use
tty_port instead of tty_struct all around.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-10-22 16:58:28 -07:00
Jiri Slaby
967fab6916 TTY: add port -> tty link
For that purpose we have to temporarily introduce a second tty back
pointer into tty_port. It is because serial layer, and maybe others,
still do not use tty_port_tty_set/get. So that we cannot set the
tty_port->tty to NULL at will now.

Yes, the fix would be to convert whole serial layer and all its users
to tty_port_tty_set/get. However we are in the process of removing the
need of tty in most of the call sites, so this would lead to a
duplicated work.

Instead we have now tty_port->itty (internal tty) which will be used
only in flush_to_ldisc. For that one it is ensured that itty is valid
wherever the work is run. IOW, the work is synchronously cancelled
before we set itty to NULL and also before hangup is processed.

After we need only tty_port and not tty_struct in most code, this
shall be changed to tty_port_tty_set/get and itty removed completely.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-10-22 16:53:40 -07:00
Jiri Slaby
fa2ecfc5a6 TTY: move devpts kill to pty
Now that we have control over tty->driver_data in pty, we can just
kill the /dev/pts/ in pty code too. Namely, in ->shutdown hook of
tty. For pty, this is called only once, for whichever end is closed
last. But we don't care, both driver_data are the inode as it used to
be till now.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-10-22 16:50:13 -07:00
Jiri Slaby
f11afb6124 TTY: devpts, do not set driver_data
The goal is to stop setting and using tty->driver_data in devpts code.
It should be used solely by the driver's code, pty in this case.

Now driver_data are managed only in the pty driver. devpts_pty_new is
switched to accept what we used to dig out of tty_struct, i.e. device
node number and index.

This also removes a note about driver_data being set outside of the
driver.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-10-22 16:50:13 -07:00
Jiri Slaby
162b97cfa2 TTY: devpts, return created inode from devpts_pty_new
The goal is to stop setting and using tty->driver_data in devpts code.
It should be used solely by the driver's code, pty in this case.

For the cleanup of layering, we will need the inode created in
devpts_pty_new to be stored into slave's driver_data. So we convert
devpts_pty_new to return the inode or an ERR_PTR-encoded error in case
of failure.

The move of 'inode = new_inode(sb);' from declarators to the code is
only cosmetical, but it makes the code easier to read.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-10-22 16:50:12 -07:00
Jiri Slaby
8fcbaa2b7f TTY: devpts, don't care about TTY in devpts_get_tty
The goal is to stop setting and using tty->driver_data in devpts code.
It should be used solely by the driver's code, pty in this case.

First, here we remove TTY from devpts_get_tty and rename it to
devpts_get_priv. Note we do not remove type safety, we just shift the
[implicit] (void *) cast one layer up.

index was unused in devpts_get_tty, so remove that from the prototype
too.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-10-22 16:50:12 -07:00
Alan Cox
05fb79e45e pty: Fix locking bug on error path
We end up dropping the mutex twice on some errors. We don't want to do
that.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-09-21 09:51:09 -07:00
Dan Carpenter
c3a6344ae4 TTY: tty_alloc_driver() returns error pointers
We changed these from alloc_tty_driver() to tty_alloc_driver() so the
error handling needs to modified to check for IS_ERR() instead of NULL.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-08-16 12:07:23 -07:00
Jiri Slaby
21aca2fa00 TTY: pty, switch to tty_alloc_driver
Switch to the new driver allocation interface, as this is one of the
special call-sites. Here, we need TTY_DRIVER_DYNAMIC_ALLOC to not
allocate tty_driver->ports, cdevs and potentially other structures
because we reserve too many lines in pty. Instead, it provides the
tty_port<->tty_struct link in tty->ops->install already.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-08-13 16:45:38 -07:00
Jiri Slaby
6f9ea7ad7b TTY: pty, stop passing NULL to free_tty_struct
In case alloc_tty_struct fails in pty_common_install, we pass NULL to
free_tty_struct. This is invalid as the function is not ready to cope
with that. And even if it was, it is not nice to do that anyway.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-08-10 13:27:50 -07:00
Alan Cox
89c8d91e31 tty: localise the lock
The termios and other changes mean the other protections needed on the driver
tty arrays should be adequate. Turn it all back on.

This contains pieces folded in from the fixes made to the original patches

| From: Geert Uytterhoeven <geert@linux-m68k.org>	(fix m68k)
| From: Paul Gortmaker <paul.gortmaker@windriver.com>	(fix cris)
| From: Jiri Kosina <jkosina@suze.cz>			(lockdep)
| From: Eric Dumazet <eric.dumazet@gmail.com>		(lockdep)

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-08-10 12:55:47 -07:00
Alan Cox
d155255a34 tty: Fix race in tty release
Ian Abbott found that the tty layer would explode with the right set of
parallel open and close operations. This is because we race in the
handling of tty->drivers->termios[].

Correct this by
	Making tty_ldisc_release behave like nromal code (takes the lock,
			does stuff, drops the lock)
	Drop the tty lock earlier in tty_ldisc_release
	Taking the tty mutex around the driver->termios update in all cases
	Adding a WARN_ON to catch future screwups.

I also forgot to clean up the pty resources properly. With a pty pair we
need to pull both halves out of the tables.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Tested-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-07-27 11:55:59 -07:00
Alan Cox
36b3c070d2 tty: Move the handling of the tty release logic
Now that we don't have tty->termios tied to drivers->tty we can untangle
the logic here. In addition we can push the removal logic out of the
destructor path.

At that point we can think about sorting out tty_port and console and all
the other ugly hangovers.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-07-17 09:13:38 -07:00