linux-toradex.git/kernel, branch v2.6.32.58

PM / Sleep: Fix freezer failures due to racy usermodehelper_is_disabled()

2012-03-04T17:49:23+00:00

[ Upstream commit b298d289c79211508f11cb50749b0d1d54eb244a ]

Commit a144c6a (PM: Print a warning if firmware is requested when tasks
are frozen) introduced usermodehelper_is_disabled() to warn and exit
immediately if firmware is requested when usermodehelpers are disabled.

However, it is racy. Consider the following scenario, currently used in
drivers/base/firmware_class.c:

...
if (usermodehelper_is_disabled())
        goto out;

/* Do actual work */
...

out:
        return err;

Nothing prevents someone from disabling usermodehelpers just after the check
in the 'if' condition, which means that it is quite possible to try doing the
"actual work" with usermodehelpers disabled, leading to undesirable
consequences.

In particular, this race condition in _request_firmware() causes task freezing
failures whenever suspend/hibernation is in progress because, it wrongly waits
to get the firmware/microcode image from userspace when actually the
usermodehelpers are disabled or userspace has been frozen.
Some of the example scenarios that cause freezing failures due to this race
are those that depend on userspace via request_firmware(), such as x86
microcode module initialization and microcode image reload.

Previous discussions about this issue can be found at:
http://thread.gmane.org/gmane.linux.kernel/1198291/focus=1200591

This patch adds proper synchronization to fix this issue.

It is to be noted that this patchset fixes the freezing failures but doesn't
remove the warnings. IOW, it does not attempt to add explicit synchronization
to x86 microcode driver to avoid requesting microcode image at inopportune
moments. Because, the warnings were introduced to highlight such cases, in the
first place. And we need not silence the warnings, since we take care of the
*real* problem (freezing failure) and hence, after that, the warnings are
pretty harmless anyway.

Signed-off-by: Srivatsa S. Bhat 
Signed-off-by: Rafael J. Wysocki 
Signed-off-by: Greg Kroah-Hartman

PM: Print a warning if firmware is requested when tasks are frozen

2012-03-04T17:49:23+00:00

[ Upstream commit a144c6a6c924aa1da04dd77fb84b89927354fdff ]

Some drivers erroneously use request_firmware() from their ->resume()
(or ->thaw(), or ->restore()) callbacks, which is not going to work
unless the firmware has been built in.  This causes system resume to
stall until the firmware-loading timeout expires, which makes users
think that the resume has failed and reboot their machines
unnecessarily.  For this reason, make _request_firmware() print a
warning and return immediately with error code if it has been called
when tasks are frozen and it's impossible to start any new usermode
helpers.

Signed-off-by: Rafael J. Wysocki 
Acked-by: Greg Kroah-Hartman 
Reviewed-by: Valdis Kletnieks 
Signed-off-by: Srivatsa S. Bhat 
Signed-off-by: Greg Kroah-Hartman

relay: prevent integer overflow in relay_open()

2012-03-04T17:49:19+00:00

commit f6302f1bcd75a042df69866d98b8d775a668f8f1 upstream.

"subbuf_size" and "n_subbufs" come from the user and they need to be
capped to prevent an integer overflow.

Signed-off-by: Dan Carpenter 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

kprobes: initialize before using a hlist

2012-01-25T21:53:25+00:00

commit d496aab567e7e52b3e974c9192a5de6e77dce32c upstream.

Commit ef53d9c5e ("kprobes: improve kretprobe scalability with hashed
locking") introduced a bug where we can potentially leak
kretprobe_instances since we initialize a hlist head after having used
it.

Initialize the hlist head before using it.

Reported by: Jim Keniston 
Acked-by: Jim Keniston 
Signed-off-by: Ananth N Mavinakayanahalli 
Acked-by: Masami Hiramatsu 
Cc: Srinivasa D S 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

PM / Sleep: Fix race between CPU hotplug and freezer

2012-01-12T19:40:11+00:00

commit 79cfbdfa87e84992d509e6c1648a18e1d7e68c20 upstream.

The CPU hotplug notifications sent out by the _cpu_up() and _cpu_down()
functions depend on the value of the 'tasks_frozen' argument passed to them
(which indicates whether tasks have been frozen or not).
(Examples for such CPU hotplug notifications: CPU_ONLINE, CPU_ONLINE_FROZEN,
CPU_DEAD, CPU_DEAD_FROZEN).

Thus, it is essential that while the callbacks for those notifications are
running, the state of the system with respect to the tasks being frozen or
not remains unchanged, *throughout that duration*. Hence there is a need for
synchronizing the CPU hotplug code with the freezer subsystem.

Since the freezer is involved only in the Suspend/Hibernate call paths, this
patch hooks the CPU hotplug code to the suspend/hibernate notifiers
PM_[SUSPEND|HIBERNATE]_PREPARE and PM_POST_[SUSPEND|HIBERNATE] to prevent
the race between CPU hotplug and freezer, thus ensuring that CPU hotplug
notifications will always be run with the state of the system really being
what the notifications indicate, _throughout_ their execution time.

Signed-off-by: Srivatsa S. Bhat 
Signed-off-by: Rafael J. Wysocki 
Signed-off-by: Greg Kroah-Hartman

hung_task: fix false positive during vfork

2012-01-06T23:38:03+00:00

commit f9fab10bbd768b0e5254e53a4a8477a94bfc4b96 upstream.

vfork parent uninterruptibly and unkillably waits for its child to
exec/exit. This wait is of unbounded length. Ignore such waits
in the hung_task detector.

Signed-off-by: Mandeep Singh Baines 
Reported-by: Sasha Levin 
LKML-Reference: <1325344394.28904.43.camel@lappy>
Cc: Linus Torvalds 
Cc: Ingo Molnar 
Cc: Peter Zijlstra 
Cc: Andrew Morton 
Cc: John Kacur 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

Revert "clockevents: Set noop handler in clockevents_exchange_device()"

2012-01-03T17:49:22+00:00

commit 3b87487ac5008072f138953b07505a7e3493327f upstream.

This reverts commit de28f25e8244c7353abed8de0c7792f5f883588c.

It results in resume problems for various people. See for example

  http://thread.gmane.org/gmane.linux.kernel/1233033
  http://thread.gmane.org/gmane.linux.kernel/1233389
  http://thread.gmane.org/gmane.linux.kernel/1233159
  http://thread.gmane.org/gmane.linux.kernel/1227868/focus=1230877

and the fedora and ubuntu bug reports

  https://bugzilla.redhat.com/show_bug.cgi?id=767248
  https://bugs.launchpad.net/ubuntu/+source/linux/+bug/904569

which got bisected down to the stable version of this commit.

Reported-by: Jonathan Nieder 
Reported-by: Phil Miller 
Reported-by: Philip Langdale 
Reported-by: Tim Gardner 
Cc: Thomas Gleixner 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

Make TASKSTATS require root access

2011-12-21T21:04:53+00:00

commit 1a51410abe7d0ee4b1d112780f46df87d3621043 upstream.

Ok, this isn't optimal, since it means that 'iotop' needs admin
capabilities, and we may have to work on this some more.  But at the
same time it is very much not acceptable to let anybody just read
anybody elses IO statistics quite at this level.

Use of the GENL_ADMIN_PERM suggested by Johannes Berg as an alternative
to checking the capabilities by hand.

Reported-by: Vasiliy Kulikov 
Cc: Johannes Berg 
Acked-by: Balbir Singh 
Signed-off-by: Linus Torvalds 
Cc: Moritz Mühlenhoff 
Signed-off-by: Greg Kroah-Hartman

clockevents: Set noop handler in clockevents_exchange_device()

2011-12-09T17:21:52+00:00

commit de28f25e8244c7353abed8de0c7792f5f883588c upstream.

If a device is shutdown, then there might be a pending interrupt,
which will be processed after we reenable interrupts, which causes the
original handler to be run. If the old handler is the (broadcast)
periodic handler the shutdown state might hang the kernel completely.

Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

tick-broadcast: Stop active broadcast device when replacing it

2011-12-09T17:21:51+00:00

commit c1be84309c58b1e7c6d626e28fba41a22b364c3d upstream.

When a better rated broadcast device is installed, then the current
active device is not disabled, which results in two running broadcast
devices.

Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman