linux-stable.git/drivers/tty/sysrq.c, branch linux-3.9.y

sysrq: don't depend on weak undefined arrays to have an address that compares as NULL

2013-02-27T17:59:50+00:00

When taking an address of an extern array, gcc quite naturally should be
able to say "an address of an object can never be NULL" and just
optimize away the test entirely.

However, the new alternate sysrq reset code (commit 154b7a489a5b:
"Input: sysrq - allow specifying alternate reset sequence") did exactly
that, and declared platform_sysrq_reset_seq[] as a weak array, and
expecting that testing the address of the array would show whether it
actually got linked against something or not.

And that doesn't work with all gcc versions.  Clearly it works with
*some* versions of gcc, and maybe it's even supposed to work, but it
really is a very fragile concept.

So instead of testing the address of the weak variable, just create a
weak instance of that array that is empty.  If some platform then has a
real platform_sysrq_reset_seq[] that overrides our weak one, the linker
will switch to that one, and it all works without any run-time
conditionals at all.

Reported-by: Dave Airlie 
Cc: David Howells 
Cc: Russell King 
Cc: Dmitry Torokhov 
Acked-by: Mathieu Poirier 
Signed-off-by: Linus Torvalds

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input

2013-02-20T19:00:43+00:00

Pull input updates from Dmitry Torokhov:
 "Two new touchpad drivers - Cypress APA I2C Trackpad and Cypress PS/2
  touchpad and a big update to ALPS driver from Kevin Cernekee that adds
  support for "Rushmore" touchpads and paves way for adding support for
  "Dolphin" touchpads.

  There is also a new input driver for Goldfish emulator and also
  Android keyreset driver was folded into SysRq code.

  A few more drivers were updated with device tree bindings and others
  got some small cleanups and fixes."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input: (55 commits)
  Input: cyttsp-spi - remove duplicate MODULE_ALIAS()
  Input: tsc2005 - add MODULE_ALIAS
  Input: tegra-kbc - require CONFIG_OF, remove platform data
  Input: synaptics - initialize pointer emulation usage
  Input: MT - do not apply filtering on emulated events
  Input: bma150 - make some defines public and fix some comments
  Input: bma150 - fix checking pm_runtime_get_sync() return value
  Input: ALPS - enable trackstick on Rushmore touchpads
  Input: ALPS - add support for "Rushmore" touchpads
  Input: ALPS - make the V3 packet field decoder "pluggable"
  Input: ALPS - move pixel and bitmap info into alps_data struct
  Input: ALPS - fix command mode check
  Input: ALPS - rework detection of Pinnacle AGx touchpads
  Input: ALPS - move {addr,nibble}_command settings into alps_set_defaults()
  Input: ALPS - use function pointers for different protocol handlers
  Input: ALPS - rework detection sequence
  Input: ALPS - introduce helper function for repeated commands
  Input: ALPS - move alps_get_model() down below hw_init code
  Input: ALPS - copy "model" info into alps_data struct
  Input: ALPS - document the alps.h data structures
  ...

sched/rt: Move rt specific bits into new header file

2013-02-07T19:51:08+00:00

Move rt scheduler definitions out of include/linux/sched.h into
new file include/linux/sched/rt.h

Signed-off-by: Clark Williams 
Cc: Peter Zijlstra 
Cc: Steven Rostedt 
Link: http://lkml.kernel.org/r/20130207094707.7b9f825f@riff.lan
Signed-off-by: Ingo Molnar

Input: sysrq - allow specifying alternate reset sequence

2013-01-17T08:27:52+00:00

This patch adds keyreset functionality to the sysrq driver. It allows
certain button/key combinations to be used in order to trigger emergency
reboots.

Redefining the '__weak platform_sysrq_reset_seq' variable is required
to trigger the feature.  Alternatively keys can be passed to the driver
via a module parameter.

This functionality comes from the keyreset driver submitted by
Arve Hjønnevåg in the Android kernel.

Signed-off-by: Mathieu Poirier 
Signed-off-by: Dmitry Torokhov

mm, oom: ensure sysrq+f always passes valid zonelist

2012-11-16T01:13:48+00:00

With hotpluggable and memoryless nodes, it's possible that node 0 will
not be online, so use the first online node's zonelist rather than
hardcoding node 0 to pass a zonelist with all zones to the oom killer.

Signed-off-by: David Rientjes 
Reviewed-by: Michal Hocko 
Signed-off-by: Greg Kroah-Hartman

sparc64: Add global PMU register dumping via sysrq.

2012-10-16T16:34:01+00:00

Signed-off-by: David S. Miller

sysrq: use SEND_SIG_FORCED instead of force_sig()

2012-04-05T22:25:50+00:00

Change send_sig_all() to use do_send_sig_info(SEND_SIG_FORCED) instead
of force_sig(SIGKILL).  With the recent changes we do not need force_ to
kill the CLONE_NEWPID tasks.

And this is more correct.  force_sig() can race with the exiting thread,
while do_send_sig_info(group => true) kill the whole process.

Some more notes from Oleg Nesterov:

> Just one note. This change makes no difference for sysrq_handle_kill().
> But it obviously changes the behaviour sysrq_handle_term(). I think
> this is fine, if you want to really kill the task which blocks/ignores
> SIGTERM you can use sysrq_handle_kill().
>
> Even ignoring the reasons why force_sig() is simply wrong here,
> force_sig(SIGTERM) looks strange. The task won't be killed if it has
> a handler, but SIG_IGN can't help. However if it has the handler
> but blocks SIGTERM temporary (this is very common) it will be killed.

Also,

> force_sig() can't kill the process if the main thread has already
> exited. IOW, it is trivial to create the process which can't be
> killed by sysrq.

So, this patch fixes the issue.

Suggested-by: Oleg Nesterov 
Acked-by: Greg Kroah-Hartman 
Acked-by: Oleg Nesterov 
Signed-off-by: Anton Vorontsov 
Cc: Alan Cox 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm, oom: force oom kill on sysrq+f

2012-03-22T00:54:58+00:00

The oom killer chooses not to kill a thread if:

 - an eligible thread has already been oom killed and has yet to exit,
   and

 - an eligible thread is exiting but has yet to free all its memory and
   is not the thread attempting to currently allocate memory.

SysRq+F manually invokes the global oom killer to kill a memory-hogging
task.  This is normally done as a last resort to free memory when no
progress is being made or to test the oom killer itself.

For both uses, we always want to kill a thread and never defer.  This
patch causes SysRq+F to always kill an eligible thread and can be used to
force a kill even if another oom killed thread has failed to exit.

Signed-off-by: David Rientjes 
Acked-by: KOSAKI Motohiro 
Acked-by: Pekka Enberg 
Acked-by: KAMEZAWA Hiroyuki 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

vt:tackle kbd_table

2012-03-08T18:50:35+00:00

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 
Signed-off-by: Greg Kroah-Hartman

sysrq: Properly check for kernel threads

2012-02-09T17:03:30+00:00

There's a real possibility of killing kernel threads that might
have issued use_mm(), so kthread's mm might become non-NULL.

This patch fixes the issue by checking for PF_KTHREAD (just as
get_task_mm()).

Suggested-by: Oleg Nesterov 
Signed-off-by: Anton Vorontsov 
Acked-by: David Rientjes 
Signed-off-by: Greg Kroah-Hartman