hrtimer: Don't reinitialize a cpu_base's lock on CPU_UP

The current code makes the assumption that a cpu_base lock cannot
be held if a CPU is offline, which is tragically wrong.

If a hrtimer is not queued, then it will not be migrated by
migrate_hrtimers() when a CPU is offlined. Therefore, the
hrtimer's cpu_base may still point to a CPU which has
subsequently gone offline if the timer wasn't enqueued at the
time the CPU went down.

Normally this wouldn't be a problem, but a cpu_base's lock is
blindly reinitialized each time a CPU is brought up. If a CPU is
brought online during the period that another thread is
performing a hrtimer operation on a stale hrtimer, then the lock
will be reinitialized under its feet, and a SPIN_BUG() like the
following will be observed:

 [  448.212369] BUG: spinlock already unlocked on CPU#3,
 swapper/3/0
[  448.217368]  lock: 0xc47b1a40, .magic: dead4ead, .owner:
swapper/3/0, .owner_cpu: -1
[  448.217398] [<c0014398>] (unwind_backtrace+0x0/0x120) from
[<c0269ab0>] (do_raw_spin_unlock+0x44/0xdc)
[  448.217419] [<c0269ab0>] (do_raw_spin_unlock+0x44/0xdc) from
[<c071bbb0>] (_raw_spin_unlock_irqrestore+0xc/0x38)
[  448.217438] [<c071bbb0>]
(_raw_spin_unlock_irqrestore+0xc/0x38) from [<c00aa498>]
(hrtimer_try_to_cancel+0xf8/0x10c)
[  448.217455] [<c00aa498>] (hrtimer_try_to_cancel+0xf8/0x10c)
from [<c00aa4bc>] (hrtimer_cancel+0x10/0x20)
[  448.217475] [<c00aa4bc>] (hrtimer_cancel+0x10/0x20) from
[<c00e6934>] (rcu_idle_exit_common+0x5c/0xe0)
[  448.217494] [<c00e6934>] (rcu_idle_exit_common+0x5c/0xe0) from
[<c00e6ae8>] (rcu_idle_exit+0x9c/0xb4)
[  448.217514] [<c00e6ae8>] (rcu_idle_exit+0x9c/0xb4) from
[<c000f2dc>] (cpu_idle+0x98/0xf0)
[  448.217529] [<c000f2dc>] (cpu_idle+0x98/0xf0) from
[<000081ac>] (0x81ac)

CRs-Fixed: 460670
Change-Id: I588f6a864054abe6d4c249aad815c6d2f5a54077
Signed-off-by: Michael Bohan <mbohan@codeaurora.org>
Signed-off-by: Ajay Dudani <adudani@codeaurora.org>

Conflicts:
	kernel/hrtimer.c
sched: Unthrottle rt runqueues in __disable_runtime()

migrate_tasks() uses _pick_next_task_rt() to get tasks from the
real-time runqueues to be migrated. When rt_rq is throttled
_pick_next_task_rt() won't return anything, in which case
migrate_tasks() can't move all threads over and gets stuck in an
infinite loop.

Instead unthrottle rt runqueues before migrating tasks.

Additionally: move unthrottle_offline_cfs_rqs() to rq_offline_fair()

Change-Id: If8a4a399f1a14b7f4789c1b205dcfadbde555214
Signed-off-by: Peter Boonstoppel <pboonstoppel@nvidia.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Turner <pjt@google.com>
Link: http://lkml.kernel.org/r/5FBF8E85CA34454794F0F7ECBA79798F379D3648B7@HQMAIL04.nvidia.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Git-commit: a4c96ae319b8047f62dedbe1eac79e321c185749
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
Revert "msm: move printk out of spin lock low_water_lock"

This reverts commit 749c4210f338496abf2e16ef51308ff756b34f7b.

This patch is a hack intended to solve a particular instance of a more
generic problem. The cause of the spindump timeout has been fixed with
the commit f37a3dc536e4ecd72961a2d9c77f5587c5c55d8f. Furthermore this
change also introduces a race condition since the printk is actually
intended to be protected with the spinlock.

Change-Id: I8ca057f47760c7bb5b826cceeac92ae5e124e904
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
PM / QoS: Fix deadlock during PM QoS vote to default value

pm_qos_work_fn() calls pm_qos_update_request() which does
cancel_delayed_work_sync() on the same pm_qos_work_fn()
causing deadlock. Fix this by updating the target with
default timeout value directly instead of calling
pm_qos_update_request().

CRs-Fixed: 526216
Change-Id: I7de2fb1c89f87b0ebf7427116b8920aec50d5b2b
Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org>
lib: spinlock_debug: Avoid livelock in do_raw_spin_lock

The logic in do_raw_spin_lock attempts to acquire a spinlock
by invoking arch_spin_trylock in a loop with a delay between
each attempt. Now consider the following situation in a 2
CPU system:

1. Cpu 0 continually acquires and releases a spinlock in a
   tight loop; it stays in this loop until some condition X
   is satisfied. X can only be satisfied by another CPU.

2. Cpu 1 tries to acquire the same spinlock, in an attempt
   to satisfy the aforementioned condition X. However, it
   never sees the unlocked value of the lock because the
   debug spinlock code uses trylock instead of just lock;
   it checks at all the wrong moments - whenever Cpu 0 has
   locked the lock.

Now in the absence of debug spinlocks, the architecture specific
spinlock code can correctly allow Cpu1 to wait in a "queue"
(e.g., ticket spinlocks), ensuring that it acquires the lock at
some point. However, with the debug spinlock code, livelock
can easily occur due to the use of try_lock, which obviously
cannot put the CPU in that "queue".

Address this by actually attempting arch_spin_lock once it is
suspected that there is a spinlock lockup. If we're in a
situation that is described above, the arch_spin_lock should
succeed; otherwise other timeout mechanisms (e.g., watchdog)
should alert the system of a lockup.

Additionally, the delay between each trylock attempt adds up
to a total delay of 1 second. On some embedded architectures,
this is an unacceptably large value. Reduce this to a ~62 ms
delay.

CRs-Fixed: 393351
Change-Id: I56f0d8f5e483cd7e8167fc7a363b9de7777a0830
Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>
lib: spinlock_debug: increase spin dump timeout

On certain targets the worst case console buffer draining time can
exceed the aggressive spin dump timeout value. Relax the timeout value
to cater to these scenarios.

Change-Id: I7312ffe06bafd2dc7adf0f4e8b73a53fc5839235
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
msm: acpuclock-krait: Enable HFPLL for init only if switching to it

The existing code left the HFPLL enabled in hfpll_init(), even if
the CPU was detected to be at a non-HFPLL rate. Correct this for
power savings between when hfpll_init() and the first runtime CPU
frequency switch happen. This also ensure votes for HFPLL
regulators are not left unnecessarily asserted.

Change-Id: Iaca5dc7e4769bdbd494d669726ba9b500256f793
Signed-off-by: Matt Wagantall <mattw@codeaurora.org>
trace: power: Adding trace events for cpufreq

Added two events to help debugging cpufreq:
1) cpufreq_sampling_event: To capture governor sampling instants
   when cpu load is evaluated and an appropriate frequency is
   selected.
2) cpufreq_freq_synced: to capture frequency synchronization of
   destination cpu with the source cpu triggered by foreground
   thread migrations.

Change-Id: I75bc7c3104b6e0750d9ede95602098d335f4f533
Signed-off-by: Rohit Gupta <rohgup@codeaurora.org>
tracing/sched: Add trace events to track cpu hotplug.

Add ftrace event trace_sched_cpu_hotplug to track cpu
hot-add and hot-remove events.

This is useful in a variety of power, performance and
debug analysis scenarios.

Change-Id: I5d202c7a229ffacc3aafb7cf9afee0b0ee7b0931
Signed-off-by: Arun Bharadwaj <abharadw@codeaurora.org>

Conflicts:

	kernel/cpu.c