linux-toradex.git/drivers/char/tty_io.c, branch v2.6.35

tty: Fix unbalanced BKL handling in error path

2010-05-13T19:10:56+00:00

Arnd noted:

After the "retry_open:" label, we first get the tty_mutex
and then the BKL. However a the end of tty_open, we jump
back to retry_open with the BKL still held. If we run into
this case, the tty_open function will be left with the BKL
still held.

Signed-off-by: Alan Cox 
Acked-by: Arnd Bergmann 
Cc: stable 
Signed-off-by: Greg Kroah-Hartman

tty: release_one_tty() forgets to put pids

2010-04-03T02:44:09+00:00

release_one_tty(tty) can be called when tty still has a reference
to pgrp/session. In this case we leak the pid.

Signed-off-by: Oleg Nesterov 
Reported-by: Catalin Marinas 
Reported-and-tested-by: Tetsuo Handa 
Acked-by: Linus Torvalds 
Acked-by: Eric W. Biederman 
Signed-off-by: Linus Torvalds

Merge branch 'for-next' into for-linus

2010-03-08T15:55:37+00:00

Conflicts:
	Documentation/filesystems/proc.txt
	arch/arm/mach-u300/include/mach/debug-macro.S
	drivers/net/qlge/qlge_ethtool.c
	drivers/net/qlge/qlge_main.c
	drivers/net/typhoon.c

tree-wide: Assorted spelling fixes

2010-02-09T10:13:56+00:00

In particular, several occurances of funny versions of 'success',
'unknown', 'therefore', 'acknowledge', 'argument', 'achieve', 'address',
'beginning', 'desirable', 'separate' and 'necessary' are fixed.

Signed-off-by: Daniel Mack 
Cc: Joe Perches 
Cc: Junio C Hamano 
Signed-off-by: Jiri Kosina

Fix race in tty_fasync() properly

2010-02-07T18:26:01+00:00

This reverts commit 703625118069 ("tty: fix race in tty_fasync") and
commit b04da8bfdfbb ("fnctl: f_modown should call write_lock_irqsave/
restore") that tried to fix up some of the fallout but was incomplete.

It turns out that we really cannot hold 'tty->ctrl_lock' over calling
__f_setown, because not only did that cause problems with interrupt
disables (which the second commit fixed), it also causes a potential
ABBA deadlock due to lock ordering.

Thanks to Tetsuo Handa for following up on the issue, and running
lockdep to show the problem.  It goes roughly like this:

 - f_getown gets filp->f_owner.lock for reading without interrupts
   disabled, so an interrupt that happens while that lock is held can
   cause a lockdep chain from f_owner.lock -> sighand->siglock.

 - at the same time, the tty->ctrl_lock -> f_owner.lock chain that
   commit 703625118069 introduced, together with the pre-existing
   sighand->siglock -> tty->ctrl_lock chain means that we have a lock
   dependency the other way too.

So instead of extending tty->ctrl_lock over the whole __f_setown() call,
we now just take a reference to the 'pid' structure while holding the
lock, and then release it after having done the __f_setown.  That still
guarantees that 'struct pid' won't go away from under us, which is all
we really ever needed.

Reported-and-tested-by: Tetsuo Handa 
Acked-by: Greg Kroah-Hartman 
Acked-by: Américo Wang 
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds

tty: fix race in tty_fasync

2010-01-20T23:03:31+00:00

We need to keep the lock held over the call to __f_setown() to
prevent a PID race.

Thanks to Al Viro for pointing out the problem, and to Travis for
making us look here in the first place.

Cc: Eric W. Biederman 
Cc: Al Viro 
Cc: Alan Cox 
Cc: Linus Torvalds 
Cc: Tavis Ormandy 
Cc: Jeff Dike 
Cc: Julien Tinnes 
Cc: Matt Mackall 
Cc: stable 
Signed-off-by: Greg Kroah-Hartman

tty: Fix BKL taken under a spinlock bug introduced in the BKL split

2009-12-12T22:46:21+00:00

The fasync path takes the BKL (it probably doesn't need to in fact)
while holding the file_list spinlock.  You can't do that with the kernel
lock: it causes lock inversions and deadlocks.

Leave the BKL over that bit for the moment.

Identified by AKPM.

Signed-off-by: Alan Cox 
Acked-and-Tested-by: Thomas Gleixner 
Signed-off-by: Linus Torvalds

tty: split the lock up a bit further

2009-12-11T23:18:08+00:00

The tty count sanity check may need the BKL, that isn't clear. However it
is clear that the count use of the lock is internal and independant of the
bigger use of the lock.

Furthermore the file list locking is also separately locked already

Signed-off-by: Alan Cox 
Signed-off-by: Greg Kroah-Hartman

tty: Move the leader test in disassociate

2009-12-11T23:18:08+00:00

There are two call points, both want to check that tty->signal->leader is
set. Move the test into disassociate_ctty() as that will make locking
changes easier in a bit

Signed-off-by: Alan Cox 
Signed-off-by: Greg Kroah-Hartman

tty: Push the bkl down a bit in the hangup code

2009-12-11T23:18:08+00:00

We know that the redirect field is handled via its own locking in all
places

Signed-off-by: Alan Cox 
Signed-off-by: Greg Kroah-Hartman