Linaro 4.8 fixes
Implement kexec-hardboot "Allows hard booting (i.e., with a full hardware reboot) to a kernel previously loaded in memory by kexec. This works around the problem of soft-booted kernel hangs due to improper device shutdown and/or reinitialization." More info in /arch/arm/Kconfig.

Original author: Mike Kasick <mike@kasick.org>

Vojtech Bocek <vbocek@gmail.com>:
  I've ported it to flo, it is based of my grouper port, which is based of
  Asus TF201 patches ported by Jens Andersen <jens.andersen@gmail.com>.

  I've moved atags copying from guest to the host kernel, which means there
  is no need to patch the guest kernel, assuming the --mem-min in kexec call
  is within the first 256MB of System RAM, otherwise it will take a long time
  to load. I've also fixed /proc/atags entry, which would give the kexec-tools
  userspace binary only the first 1024 bytes of atags,
  see arch/arm/kernel/atags.c for more details.

  Other than that, memory-reservation code for the hardboot page and
  some assembler to do the watchdog reset on MSM chip are new for this device.

Signed-off-by: Vojtech Bocek <vbocek@gmail.com>

Signed-off-by: Paul Reioux <reioux@gmail.com>
kexec: use mem_text_write_kernel_word to set reboot_code_buffer args

* In order to avoid protection faults (writes to read-only
  kernel memory) when CONFIG_STRICT_MEMORY_RWX is enabled.

Signed-off-by: Vojtech Bocek <vbocek@gmail.com>
Add kexec-hardboot changes for mako

Signed-off-by: Paul Reioux <reioux@gmail.com>
sched/rt: Remove redundant nr_cpus_allowed test

Date	Fri, 4 Oct 2013 14:24:53 -0500

From: Shawn Bohrer <sbohrer@rgmadvisors.com>

In 76854c7e8f3f4172fef091e78d88b3b751463ac6 "sched: Use
rt.nr_cpus_allowed to recover select_task_rq() cycles" an optimization
was added to select_task_rq_rt() that immediately returns when
p->nr_cpus_allowed == 1 at the beginning of the function.  This makes
the latter p->nr_cpus_allowed > 1 check redundant and can be removed.
Signed-off-by: Shawn Bohrer <sbohrer@rgmadvisors.com>

Signed-off-by: Paul Reioux <reioux@gmail.com>
fs: vfat: reduce the worst case latencies

When a block partition is mounted with FAT file system
and MS_DIRSYNC option is used, some file system operations
like create, rename shall sleep in caller's context until
all the metadata have been committed to the non-volatile memory.
Since this operation is blocking call for user context,
the WRITE_SYNC option must be used instead of WRITE
(async operation) which incur inherent latencies while
flushing the meta-data corresponding to directory entries

Change-Id: I41c514889873a39d564271db0a421e6c66e5ae33
Signed-off-by: xiaogang <xiaogang@codeaurora.org>
CHROMIUM: mm: Fix calculation of dirtyable memory

The system uses global_dirtyable_memory() to calculate
number of dirtyable pages/pages that can be allocated
to the page cache.  A bug causes an underflow thus making
the page count look like a big unsigned number.  This in turn
confuses the dirty writeback throttling to aggressively write
back pages as they become dirty (usually 1 page at a time).

Fix is to ensure there is no underflow while doing the math.

Signed-off-by: Sonny Rao <sonnyrao@chromium.org>
Signed-off-by: Puneet Kumar <puneetster@chromium.org>

BUG=chrome-os-partner:16011
TEST=Manual; boot kernel, powerwash, login with testaccount and
make sure no jank occurs on sync of applications

Change-Id: I614e7c3156e014f0f28a4ef9bdd8cb8a2cd07b2a
Reviewed-on: https://gerrit.chromium.org/gerrit/37612
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Olof Johansson <olofj@chromium.org>
Commit-Ready: Puneet Kumar <puneetster@chromium.org>
Reviewed-by: Puneet Kumar <puneetster@chromium.org>
Tested-by: Puneet Kumar <puneetster@chromium.org>
Optimize EPOLL_CTL_DEL such that it does not require the 'epmutex' by
converting the file->f_ep_links list into an rcu one. In this way, we can
traverse the epoll network on the add path in parallel with deletes. Since
deletes can't create loops or worse wakeup paths, this is safe.

This patch in combination with the patch "epoll: Do not take global 'epmutex'
for simple topologies", shows a dramatic performance improvement in
scalability for SPECjbb.

Tested-by: Nathan Zimmer <nzimmer@sgi.com>
Signed-off-by: Jason Baron <jbaron@akamai.com>

backported for Linux 3.4 for use on Android
Signed-off-by: Paul Reioux <reioux@gmail.com>

*epoll: do not take globals epmutex for simple topologies fix

- use `bool' for boolean variables
- remove unneeded/undesirable cast of void*
- add missed ep_scan_ready_list() kerneldoc

Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Eric Wong <normalperson@yhbt.net>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Nathan Zimmer <nzimmer@sgi.com>
Cc: Nelson Elhage <nelhage@nelhage.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Signed-off-by: Paul Reioux <reioux@gmail.com>

*epoll: Do not take global 'epmutex' for simple topologies

Date	Tue, 1 Oct 2013 17:08:14 +0000 (GMT)

When calling EPOLL_CTL_ADD for an epoll file descriptor that is attached
directly to a wakeup source, we do not need to take the global 'epmutex',
unless the epoll file descriptor is nested. The purpose of taking
the 'epmutex' on add is to prevent complex topologies such as loops and
deep wakeup paths from forming in parallel through multiple EPOLL_CTL_ADD
operations. However, for the simple case of an epoll file descriptor
attached directly to a wakeup source (with no nesting), we do not need
to hold the 'epmutex'.

This patch along with 'epoll: optimize EPOLL_CTL_DEL using rcu' improves
scalability on larger systems. Quoting Nathan Zimmer's mail on SPECjbb
performance:

"
On the 16 socket run the performance went from 35k jOPS to 125k jOPS.
In addition the benchmark when from scaling well on 10 sockets to scaling well
on just over 40 sockets.

...

Currently the benchmark stops scaling at around 40-44 sockets but it seems like
I found a second unrelated bottleneck.
"

Tested-by: Nathan Zimmer <nzimmer@sgi.com>
Signed-off-by: Jason Baron <jbaron@akamai.com>

backported to Linux 3.4 for use on Android
Signed-off-by: Paul Reioux <reioux@gmail.com>
epoll: optimize EPOLL_CTL_DEL using rcu

Date	Tue, 1 Oct 2013 17:08:10 +0000 (GMT)