hrtimer: Consider preemption when migrating hrtimer cpu_bases

When switching to a new cpu_base in switch_hrtimer_base(), we
briefly enable preemption by unlocking the cpu_base lock in two
places. During this interval it's possible for the running thread
to be swapped to a different CPU.

Consider the following example:

CPU #0                                 CPU #1
----                                   ----
hrtimer_start()                        ...
 lock_hrtimer_base()
 switch_hrtimer_base()
  this_cpu = 0;
  target_cpu_base = 0;
  raw_spin_unlock(&cpu_base->lock)
<migrate to CPU 1>
...                                    this_cpu == 0
                                       cpu == this_cpu
                                       timer->base = CPU #0
                                       timer->base != LOCAL_CPU

Since the cached this_cpu is no longer accurate, we'll skip the
hrtimer_check_target() check. Once we eventually go to program
the hardware, we'll decide not to do so since it knows the real
CPU that we're running on is not the same as the chosen base. As
a consequence, we may end up missing the hrtimer's deadline.

Fix this by updating the local CPU number each time we retake a
cpu_base lock in switch_hrtimer_base().

Another possibility is to disable preemption across the whole of
switch_hrtimer_base.  This looks suboptimal since preemption
would be disabled while waiting for lock(s).

Change-Id: I3f76d528ab2288ef5f950f4d048e7f3fa6cf1228
Signed-off-by: Michael Bohan <mbohan@codeaurora.org>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
hrtimer: Prevent enqueue of hrtimer on dead CPU

When switching the hrtimer cpu_base, we briefly allow for
preemption to become enabled by unlocking the cpu_base lock.
During this time, the CPU corresponding to the new cpu_base
that was selected may in fact go offline. In this scenario, the
hrtimer is enqueued to a CPU that's not online, and therefore
it never fires.

As an example, consider this example:

CPU #0                          CPU #1
----                            ----
...                             hrtimer_start()
                                 lock_hrtimer_base()
                                 switch_hrtimer_base()
                                  cpu = hrtimer_get_target() -> 1
                                  spin_unlock(&cpu_base->lock)
                                <migrate thread to CPU #0>
                                <offline>
spin_lock(&new_base->lock)
this_cpu = 0
cpu != this_cpu
enqueue_hrtimer(cpu_base #1)

To prevent this scenario, verify that the CPU corresponding to
the new cpu_base is indeed online before selecting it in
hrtimer_switch_base(). If it's not online, fallback to using the
base of the current CPU.

Change-Id: I6359cb299ba7e08abf25d3360fcdd925b4c03b69
Signed-off-by: Michael Bohan <mbohan@codeaurora.org>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
usb: gadget: u_data_hsic: Use GFP_KERNEL where ever possible

The USB requests are allocated using dma pool API.  The dma pool has
limited memory for non-sleeping use case.  The current code does not
free USB requests during subsystem restart.  The requests are freed
only after cable is disconnected.  If subsystem restart happens
multiple  times without disconnecting cable, system may run out of the
dma pool memory.  This is leading to URB submission failures.  Use
GFP_KERNEL where ever possible.

CRs-Fixed: 463423
Change-Id: I0fca533e460e7b4234fe771e048e0e50494cb1da
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
USB: mdm_bridge: Fix probe error path

The platform device is not unregistered in probe error path.  The
platform device is added again during next probe and it fails.  But
the return value is not checked.  Kernel panic happens when platform
device is removed during disconnect.

CRs-Fixed: 465508
Change-Id: I4db613e72d8b405f10cde0d1335d231cf5079e64
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
block: urgent request: remove unnecessary urgent marking

An urgent request is marked by the scheduler in rq->cmd_flags with the
REQ_URGENT flag. There is no need to add an additional marking by
the block layer.

Change-Id: I05d5e9539d2f6c1bfa80240b0671db197a5d3b3f
Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>

Conflicts:
	block/test-iosched.c
block: blk-core: add printk_ratelimit

On failure of requests the console is flooded with prints,
which result in a watchdog bark.
This patch limits the number of prints to console thus, avoiding
the bark.

CRs-Fixed: 458071
Change-Id: I614002cc1305ab7b5c6a64d278139291c1baa3c4
Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
block: urgent request: Update dispatch_urgent in case of requeue/reinsert

The block layer implements a mechanism for verifying that the device
driver won't be notified of an URGENT request if there is already an
URGENT request in flight. This is due to the fact that interrupting an
URGENT request isn't efficient.
This patch fixes the above described mechanism in case the URGENT request
was returned back to the block layer from some reason: by requeue or
reinsert.

CRs-fixed: 473376, 473036, 471736
Change-Id: Ie8b8208230a302d4526068531616984825f1050d
Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
arm: mutex: merge Will Deacon's patch for including a different implementationfor mutexes for ARM6+ chips. Didn't cherry pick original patches because they conflicted for some reason and I felt too lazy to fix the conflict.

Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
block: row: Prevent starvation of regular priority by high priority

At the moment all REGULAR and LOW priority requests are starved as long as
there are HIGH priority requests to dispatch.
This patch prevents the above starvation by setting a starvation limit the
REGULAR\LOW priority requests can tolerate.

Change-Id: Ibe24207982c2c55d75c0b0230f67e013d1106017
Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
rq_stats: add report_load_at_max_freq to the header file.

Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
Revert "rq_stats: remove the sysfs entries, they are not needed now."

This reverts commit 729093a739923be3d823ec9a150c0dd1f805f5b1.
Should've used gcc 4.6 all along.

Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
rq_stats: don't need to call the update_average_load every POSTCHANGE transition, specially because we're already calling update_average_load every msecs_to_jiffies(HZ) from the Hotplug driver. With all the locks & unlocks involved plus all the time calling and making some calculations (divisions as well) we may as well don't have the stats driver to call it that much.

Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
drivers: thermal: start the thermal check 10 seconds later.

Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
mako_hotplug: add hooks so that the driver and the sysfs are synchronized with the defaults if I decide to change them in the future.

Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>