AIO: Don't plug the I/O queue in do_io_submit() Asynchronous I/O latency to a solid-state disk greatly increased between the 2.6.32 and 3.0 kernels. By removing the plug from do_io_submit(), we observed a 34% improvement in the I/O latency.

Unfortunately, at this level, we don't know if the request is to
a rotating disk or not.

Change-Id: I7101df956473ed9fd5dcff18e473dd93b688a5c1
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Cc: linux-aio@kvack.org
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
SELinux: Reduce overhead of mls_level_isvalid() function call

Date	Mon, 10 Jun 2013 13:55:08 -0400

v4->v5:
  - Fix scripts/checkpatch.pl warning.

v3->v4:
  - Merge the 2 separate while loops in ebitmap_contains() into
    a single one.

v2->v3:
  - Remove unused local variables i, node from mls_level_isvalid().

v1->v2:
 - Move the new ebitmap comparison logic from mls_level_isvalid()
   into the ebitmap_contains() helper function.
 - Rerun perf and performance tests on the latest v3.10-rc4 kernel.

While running the high_systime workload of the AIM7 benchmark on
a 2-socket 12-core Westmere x86-64 machine running 3.10-rc4 kernel
(with HT on), it was found that a pretty sizable amount of time was
spent in the SELinux code. Below was the perf trace of the "perf
record -a -s" of a test run at 1500 users:

  5.04%            ls  [kernel.kallsyms]     [k] ebitmap_get_bit
  1.96%            ls  [kernel.kallsyms]     [k] mls_level_isvalid
  1.95%            ls  [kernel.kallsyms]     [k] find_next_bit

The ebitmap_get_bit() was the hottest function in the perf-report
output.  Both the ebitmap_get_bit() and find_next_bit() functions
were, in fact, called by mls_level_isvalid(). As a result, the
mls_level_isvalid() call consumed 8.95% of the total CPU time of
all the 24 virtual CPUs which is quite a lot. The majority of the
mls_level_isvalid() function invocations come from the socket creation
system call.

Looking at the mls_level_isvalid() function, it is checking to see
if all the bits set in one of the ebitmap structure are also set in
another one as well as the highest set bit is no bigger than the one
specified by the given policydb data structure. It is doing it in
a bit-by-bit manner. So if the ebitmap structure has many bits set,
the iteration loop will be done many times.

The current code can be rewritten to use a similar algorithm as the
ebitmap_contains() function with an additional check for the
highest set bit. The ebitmap_contains() function was extended to
cover an optional additional check for the highest set bit, and the
mls_level_isvalid() function was modified to call ebitmap_contains().

With that change, the perf trace showed that the used CPU time drop
down to just 0.08% (ebitmap_contains + mls_level_isvalid) of the
total which is about 100X less than before.

  0.07%            ls  [kernel.kallsyms]     [k] ebitmap_contains
  0.05%            ls  [kernel.kallsyms]     [k] ebitmap_get_bit
  0.01%            ls  [kernel.kallsyms]     [k] mls_level_isvalid
  0.01%            ls  [kernel.kallsyms]     [k] find_next_bit

The remaining ebitmap_get_bit() and find_next_bit() functions calls
are made by other kernel routines as the new mls_level_isvalid()
function will not call them anymore.

This patch also improves the high_systime AIM7 benchmark result,
though the improvement is not as impressive as is suggested by the
reduction in CPU time spent in the ebitmap functions. The table below
shows the performance change on the 2-socket x86-64 system (with HT
on) mentioned above.

+--------------+---------------+----------------+-----------------+
|   Workload   | mean % change | mean % change  | mean % change   |
|              | 10-100 users  | 200-1000 users | 1100-2000 users |
+--------------+---------------+----------------+-----------------+
| high_systime |     +0.1%     |     +0.9%      |     +2.6%       |
+--------------+---------------+----------------+-----------------+
Signed-off-by: Waiman Long <Waiman.Long@hp.com>
Signed-off-by: Paul Reioux <reioux@gmail.com>

Change-Id: Icbdb428e318e8db18c8de3677afcfdb7ddc9904a
SELinux: include definition of new capabilities

The kernel has added CAP_WAKE_ALARM and CAP_EPOLLWAKEUP.  We need to
define these in SELinux so they can be mediated by policy.

Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
[sds: rename epollwakeup to block_suspend to match upstream merge]
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>

Change-Id: I8a3e0db15ec5f4eb05d455a57e8446a8c2b484c2
sock_diag: Fix out-of-bounds access to sock_diag_handlers[]

Userland can send a netlink message requesting SOCK_DIAG_BY_FAMILY
with a family greater or equal then AF_MAX -- the array size of
sock_diag_handlers[]. The current code does not test for this
condition therefore is vulnerable to an out-of-bound access opening
doors for a privilege escalation.

Signed-off-by: Mathias Krause <minipli@googlemail.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
ARM: 7809/1: perf: fix event validation for software group leaders
It is possible to construct an event group with a software event as a
group leader and then subsequently add a hardware event to the group.
This results in the event group being validated by adding all members
of the group to a fake PMU and attempting to allocate each event on
their respective PMU.

Unfortunately, for software events wthout a corresponding arm_pmu, this
results in a kernel crash attempting to dereference the ->get_event_idx
function pointer.

This patch fixes the problem by checking explicitly for software events
and ignoring those in event validation (since they can always be
scheduled). We will probably want to revisit this for 3.12, since the
validation checks dont appear to work correctly when dealing with
multiple hardware PMUs anyway.

Cc: <stable@vger.kernel.org>
Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Tested-by: Vince Weaver <vincent.weaver@maine.edu>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>