Commit 421b40a628 ("tty/vt: Fix vc_deallocate() lock order") changed
the behavior when deallocating VT 1. Previously if trying to
deallocate VT1 and it is busy, we would return EBUSY. The commit
changed this to return 0 (success).
This commit restores the old behavior.
Signed-off-by: Ross Lagerwall <rosslagerwall@gmail.com>
Tested-by: Mikael Pettersson <mikpe@it.uu.se>
Acked-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Now that the tty port owns the flip buffers and i/o is allowed
from the driver even when no tty is attached, the destruction
of the tty port (and the flip buffers) must ensure that no
outstanding work is pending.
Unfortunately, this creates a lock order problem with the
console_lock (see attached lockdep report [1] below).
For single console deallocation, drop the console_lock prior
to port destruction. When multiple console deallocation,
defer port destruction until the consoles have been
deallocated.
tty_port_destroy() is not required if the port has not
been used; remove from vc_allocate() failure path.
[1] lockdep report from Dave Jones <davej@redhat.com>
======================================================
[ INFO: possible circular locking dependency detected ]
3.9.0+ #16 Not tainted
-------------------------------------------------------
(agetty)/26163 is trying to acquire lock:
blocked: ((&buf->work)){+.+...}, instance: ffff88011c8b0020, at: [<ffffffff81062065>] flush_work+0x5/0x2e0
but task is already holding lock:
blocked: (console_lock){+.+.+.}, instance: ffffffff81c2fde0, at: [<ffffffff813bc201>] vt_ioctl+0xb61/0x1230
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (console_lock){+.+.+.}:
[<ffffffff810b3f74>] lock_acquire+0xa4/0x210
[<ffffffff810416c7>] console_lock+0x77/0x80
[<ffffffff813c3dcd>] con_flush_chars+0x2d/0x50
[<ffffffff813b32b2>] n_tty_receive_buf+0x122/0x14d0
[<ffffffff813b7709>] flush_to_ldisc+0x119/0x170
[<ffffffff81064381>] process_one_work+0x211/0x700
[<ffffffff8106498b>] worker_thread+0x11b/0x3a0
[<ffffffff8106ce5d>] kthread+0xed/0x100
[<ffffffff81601cac>] ret_from_fork+0x7c/0xb0
-> #0 ((&buf->work)){+.+...}:
[<ffffffff810b349a>] __lock_acquire+0x193a/0x1c00
[<ffffffff810b3f74>] lock_acquire+0xa4/0x210
[<ffffffff810620ae>] flush_work+0x4e/0x2e0
[<ffffffff81065305>] __cancel_work_timer+0x95/0x130
[<ffffffff810653b0>] cancel_work_sync+0x10/0x20
[<ffffffff813b8212>] tty_port_destroy+0x12/0x20
[<ffffffff813c65e8>] vc_deallocate+0xf8/0x110
[<ffffffff813bc20c>] vt_ioctl+0xb6c/0x1230
[<ffffffff813b01a5>] tty_ioctl+0x285/0xd50
[<ffffffff811ba825>] do_vfs_ioctl+0x305/0x530
[<ffffffff811baad1>] sys_ioctl+0x81/0xa0
[<ffffffff81601d59>] system_call_fastpath+0x16/0x1b
other info that might help us debug this:
[ 6760.076175] Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(console_lock);
lock((&buf->work));
lock(console_lock);
lock((&buf->work));
*** DEADLOCK ***
1 lock on stack by (agetty)/26163:
#0: blocked: (console_lock){+.+.+.}, instance: ffffffff81c2fde0, at: [<ffffffff813bc201>] vt_ioctl+0xb61/0x1230
stack backtrace:
Pid: 26163, comm: (agetty) Not tainted 3.9.0+ #16
Call Trace:
[<ffffffff815edb14>] print_circular_bug+0x200/0x20e
[<ffffffff810b349a>] __lock_acquire+0x193a/0x1c00
[<ffffffff8100a269>] ? sched_clock+0x9/0x10
[<ffffffff8100a269>] ? sched_clock+0x9/0x10
[<ffffffff8100a200>] ? native_sched_clock+0x20/0x80
[<ffffffff810b3f74>] lock_acquire+0xa4/0x210
[<ffffffff81062065>] ? flush_work+0x5/0x2e0
[<ffffffff810620ae>] flush_work+0x4e/0x2e0
[<ffffffff81062065>] ? flush_work+0x5/0x2e0
[<ffffffff810b15db>] ? mark_held_locks+0xbb/0x140
[<ffffffff8113c8a3>] ? __free_pages_ok.part.57+0x93/0xc0
[<ffffffff810b15db>] ? mark_held_locks+0xbb/0x140
[<ffffffff810652f2>] ? __cancel_work_timer+0x82/0x130
[<ffffffff81065305>] __cancel_work_timer+0x95/0x130
[<ffffffff810653b0>] cancel_work_sync+0x10/0x20
[<ffffffff813b8212>] tty_port_destroy+0x12/0x20
[<ffffffff813c65e8>] vc_deallocate+0xf8/0x110
[<ffffffff813bc20c>] vt_ioctl+0xb6c/0x1230
[<ffffffff810aec41>] ? lock_release_holdtime.part.30+0xa1/0x170
[<ffffffff813b01a5>] tty_ioctl+0x285/0xd50
[<ffffffff812b00f6>] ? inode_has_perm.isra.46.constprop.61+0x56/0x80
[<ffffffff811ba825>] do_vfs_ioctl+0x305/0x530
[<ffffffff812b04db>] ? selinux_file_ioctl+0x5b/0x110
[<ffffffff811baad1>] sys_ioctl+0x81/0xa0
[<ffffffff81601d59>] system_call_fastpath+0x16/0x1b
Cc: Dave Jones <davej@redhat.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
C files should include the header files that prototype their functions.
This keeps the types in sync, and eliminates warnings from GCC
(-Wmissing-prototypes) and Sparse (-Wdecl).
Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
pm_restore_console() is called from the suspend/resume path, and this
calls vt_move_to_console(), which calls vt_waitactive().
There's a race in this path which causes the process which requests the
suspend to sleep indefinitely waiting for an event which already
happened:
P1 P2
vt_move_to_console()
set_console()
schedule_console_callback()
vt_waitactive()
check n == fg_console +1
console_callback()
switch_screen()
vt_event_post() // no waiters
vt_event_wait() // forever
Fix the race by ensuring we're registered for the event before we check
if it's already completed.
Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When we do this it becomes clear the lock we should be holding is the vc
lock, and in fact many of our other helpers are properly invoked this way.
We don't at this point guarantee not to race the keyboard code but the results
of that appear harmless and that was true before we started as well.
We now have no users of tty_lock in the console driver...
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Some of this ventures into selection which is still a complete lost cause. We
are not making it any worse. It's completely busted anyway.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
At this point we have the tty_lock guarding a couple of oddities, plus the
translation and unimap still.
We also extend the console_lock in a couple of spots where coverage is wrong
and switch vcs_open to use the right lock !
[Fixed the locking issue Jiri reported]
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Keyboard struct lifetime is easy, but the locking is not and is completely
ignored by the existing code. Tackle this one head on
- Make the kbd_table private so we can run down all direct users
- Hoick the relevant ioctl handlers into the keyboard layer
- Lock them with the keyboard lock so they don't change mid keypress
- Add helpers for things like console stop/start so we isolate the poking
around properly
- Tweak the braille console so it still builds
There are a couple of FIXME locking cases left for ioctls that are so hideous
they should be addressed in a later patch. After this patch the kbd_table is
private and all the keyboard jiggery pokery is in one place.
This update fixes speakup and also a memory leak in the original.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
First step to debletcherising the vt console layer - pick a victim and fix
the locking
This is a nice simple object with its own rules so lets pick it out for
treatment. The user of the table already has a lock so we will also use the
same lock for updates.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
KDFONTOP(GET) currently fails with EIO when being run in a 32bit userland
with a 64bit kernel if the font width is not 8.
This is because of the setting of the KD_FONT_FLAG_OLD flag, which makes
con_font_get return EIO in such case.
This flag should *not* be set for KDFONTOP, since it's actually the whole
point of this flag (see comment in con_font_set for instance).
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Arthur Taylor <art@ified.ca>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
remove invalid location line in each file header after location
moved from driver/char to driver/tty
Signed-off-by: Jovi Zhang <bookjovi@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
After adding support for K_OFF in KDSKBMODE, it was forgotten to
add support for returning it in KDGKBMODE.
Signed-off-by: Arthur Taylor <art@ified.ca>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
* 'config' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl:
BKL: That's all, folks
fs/locks.c: Remove stale FIXME left over from BKL conversion
ipx: remove the BKL
appletalk: remove the BKL
x25: remove the BKL
ufs: remove the BKL
hpfs: remove the BKL
drivers: remove extraneous includes of smp_lock.h
tracing: don't trace the BKL
adfs: remove the big kernel lock
These were missed the last time I cleaned this up
globally, because of code moving around or new code
getting merged.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Only oddities here are a couple of drivers that bogusly called the ldisc
helpers instead of returning -ENOIOCTLCMD. Fix the bug and the rest goes
away.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
using VT_SETACTIVATE ioctl for console switch did not work,
since it put wrong param to the set_console function.
Also ioctl returned misleading error, because of the missing
break statement. I wonder anyone has ever used this one :).
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
virtual console: add keyboard mode OFF
Add a new mode for the virtual console keyboard OFF in which all input
other than shift keys is ignored. Prevents vt input buffers from
overflowing when a program opens but doesn't read from a tty, like X11
using evdev for input.
Signed-off-by: Arthur Taylor <art@ified.ca>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
The -rt patches change the console_semaphore to console_mutex. As a
result, a quite large chunk of the patches changes all
acquire/release_console_sem() to acquire/release_console_mutex()
This commit makes things use more neutral function names which dont make
implications about the underlying lock.
The only real change is the return value of console_trylock which is
inverted from try_acquire_console_sem()
This patch also paves the way to switching console_sem from a semaphore to
a mutex.
[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: make console_trylock return 1 on success, per Geert]
Signed-off-by: Torben Hohn <torbenh@gmx.de>
Cc: Thomas Gleixner <tglx@tglx.de>
Cc: Greg KH <gregkh@suse.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The vt and other related code is moved into the drivers/tty/vt directory.
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
