mutex: Place lock in contended state after fastpath_lock failure

ARM recently moved to asm-generic/mutex-xchg.h for its mutex
implementation after the previous implementation was found to be missing
some crucial memory barriers. However, this has revealed some problems
running hackbench on SMP platforms due to the way in which the
MUTEX_SPIN_ON_OWNER code operates.

The symptoms are that a bunch of hackbench tasks are left waiting on an
unlocked mutex and therefore never get woken up to claim it. This boils
down to the following sequence of events:

        Task A        Task B        Task C        Lock value
0                                                     1
1       lock()                                        0
2                     lock()                          0
3                     spin(A)                         0
4       unlock()                                      1
5                                   lock()            0
6                     cmpxchg(1,0)                    0
7                     contended()                    -1
8       lock()                                        0
9       spin(C)                                       0
10                                  unlock()          1
11      cmpxchg(1,0)                                  0
12      unlock()                                      1

At this point, the lock is unlocked, but Task B is in an uninterruptible
sleep with nobody to wake it up.

This patch fixes the problem by ensuring we put the lock into the
contended state if we fail to acquire it on the fastpath, ensuring that
any blocked waiters are woken up when the mutex is released.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Chris Mason <chris.mason@fusionio.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: <stable@vger.kernel.org>
Reviewed-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-6e9lrw2avczr0617fzl5vqb8@git.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
ARM: 7467/1: mutex: use generic xchg-based implementation for ARMv6+

The open-coded mutex implementation for ARMv6+ cores suffers from a
severe lack of barriers, so in the uncontended case we don't actually
protect any accesses performed during the critical section.

Furthermore, the code is largely a duplication of the ARMv6+ atomic_dec
code but optimised to remove a branch instruction, as the mutex fastpath
was previously inlined. Now that this is executed out-of-line, we can
reuse the atomic access code for the locking (in fact, we use the xchg
code as this produces shorter critical sections).

This patch uses the generic xchg based implementation for mutexes on
ARMv6+, which introduces barriers to the lock/unlock operations and also
has the benefit of removing a fair amount of inline assembly code.

Cc: <stable@vger.kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Nicolas Pitre <nico@linaro.org>
Reported-by: Shan Kang <kangshan0910@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
net: wireless: bcmdhd: Adjust roaming treshold to -65 dB

Change-Id: I88bb0cf759ee4262f31f054ef2dd5fc6258e8628
Signed-off-by: Dmitry Shmidt <dimitrysh@google.com>
net: PPPoPNS and PPPoLAC update to use PPP_MRU instead of PPP_MRU

Some headers files were moved around and some defines renamed.

Signed-off-by: JP Abgrall <jpa@google.com>
Revert cpufreq_interactive.c: Add a time view concept
cpufreq: interactive: change frequency up/down kernel thread priority. Now it has more priority than any user thread which should boost interactivity.

Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
cpufreq: interactive: add input_boost_freq entry. This entry is the frequency which the CPU will be boosted when the screen is touched. It's user configurable from userspace and it needs to match the entries in the frequency table.

Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
bq27541: Add current_now property

The current is returned by the charger as a twos
complement signed integer in milliamps.  Applications
such as CurrentWidget expect this to be microamps.

Signed-off-by: Andrew Dodd <atd7@cornell.edu>
Change-Id: I053b3d1f24ec04391e982fdcb4b3486241c3aa34
bq27541: Correct scaling of voltage_now

This is supposed to return the voltage in uV, not mV.

Change-Id: I13f084f8c5f41f89a7e6c7cfd86e8806229a159b
Signed-off-by: Andrew Dodd <atd7@cornell.edu>
Revert cpufreq: interactive: remove input_boost handling
cpufreq: interactive: add tunable explanation.

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