Create a new socket level option to report number of queue overflows
Recently I augmented the AF_PACKET protocol to report the number of frames lost
on the socket receive queue between any two enqueued frames. This value was
exported via a SOL_PACKET level cmsg. AFter I completed that work it was
requested that this feature be generalized so that any datagram oriented socket
could make use of this option. As such I've created this patch, It creates a
new SOL_SOCKET level option called SO_RXQ_OVFL, which when enabled exports a
SOL_SOCKET level cmsg that reports the nubmer of times the sk_receive_queue
overflowed between any two given frames. It also augments the AF_PACKET
protocol to take advantage of this new feature (as it previously did not touch
sk->sk_drops, which this patch uses to record the overflow count). Tested
successfully by me.
Notes:
1) Unlike my previous patch, this patch simply records the sk_drops value, which
is not a number of drops between packets, but rather a total number of drops.
Deltas must be computed in user space.
2) While this patch currently works with datagram oriented protocols, it will
also be accepted by non-datagram oriented protocols. I'm not sure if thats
agreeable to everyone, but my argument in favor of doing so is that, for those
protocols which aren't applicable to this option, sk_drops will always be zero,
and reporting no drops on a receive queue that isn't used for those
non-participating protocols seems reasonable to me. This also saves us having
to code in a per-protocol opt in mechanism.
3) This applies cleanly to net-next assuming that commit
977750076d (my af packet cmsg patch) is reverted
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Revert 45d80eea87 ("m68k: convert to
asm-generic/hardirq.h") - it fails to compile due to an inclusion tangle:
In file included from include/linux/irq.h:12,
from include/asm-generic/hardirq.h:6,
from /usr/src/devel/arch/m68k/include/asm/hardirq_mm.h:6,
from /usr/src/devel/arch/m68k/include/asm/hardirq.h:4,
from include/linux/hardirq.h:10,
from /usr/src/devel/arch/m68k/include/asm/system_mm.h:69,
from /usr/src/devel/arch/m68k/include/asm/system.h:4,
from include/linux/list.h:7,
from include/linux/preempt.h:11,
from include/linux/spinlock.h:50,
from include/linux/seqlock.h:29,
from include/linux/time.h:8,
from include/linux/timex.h:56,
from include/linux/sched.h:56,
from arch/m68k/kernel/asm-offsets.c:14:
include/linux/smp.h:17: error: field 'list' has incomplete type
Cc: Christoph Hellwig <hch@lst.de>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* remove asm/atomic.h inclusion from linux/utsname.h --
not needed after kref conversion
* remove linux/utsname.h inclusion from files which do not need it
NOTE: it looks like fs/binfmt_elf.c do not need utsname.h, however
due to some personality stuff it _is_ needed -- cowardly leave ELF-related
headers and files alone.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* git://git.kernel.org/pub/scm/linux/kernel/git/sam/kbuild-next: (30 commits)
Use macros for .data.page_aligned section.
Use macros for .bss.page_aligned section.
Use new __init_task_data macro in arch init_task.c files.
kbuild: Don't define ALIGN and ENTRY when preprocessing linker scripts.
arm, cris, mips, sparc, powerpc, um, xtensa: fix build with bash 4.0
kbuild: add static to prototypes
kbuild: fail build if recordmcount.pl fails
kbuild: set -fconserve-stack option for gcc 4.5
kbuild: echo the record_mcount command
gconfig: disable "typeahead find" search in treeviews
kbuild: fix cc1 options check to ensure we do not use -fPIC when compiling
checkincludes.pl: add option to remove duplicates in place
markup_oops: use modinfo to avoid confusion with underscored module names
checkincludes.pl: provide usage helper
checkincludes.pl: close file as soon as we're done with it
ctags: usability fix
kernel hacking: move STRIP_ASM_SYMS from General
gitignore usr/initramfs_data.cpio.bz2 and usr/initramfs_data.cpio.lzma
kbuild: Check if linker supports the -X option
kbuild: introduce ld-option
...
Fix trivial conflict in scripts/basic/fixdep.c
Convert m68k to use GENERIC_TIME via the arch_getoffset() infrastructure,
reducing the amount of arch specific code we need to maintain.
I've taken my best swing at converting this, but I'm not 100% confident
I got it right. My cross-compiler is now out of date (gcc4.2) so I
wasn't able to check if it compiled. Any assistance from arch
maintainers or testers to get this merged would be great.
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
A number of architectures have identical asm/mman.h files so they can all
be merged by using the new generic file.
The remaining asm/mman.h files are substantially different from each
other.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add a flag for mmap that will be used to request a huge page region that
will look like anonymous memory to user space. This is accomplished by
using a file on the internal vfsmount. MAP_HUGETLB is a modifier of
MAP_ANONYMOUS and so must be specified with it. The region will behave
the same as a MAP_ANONYMOUS region using small pages.
The patch also adds the MAP_STACK flag, which was previously defined only
on some architectures but not on others. Since MAP_STACK is meant to be a
hint only, architectures can define it without assigning a specific
meaning to it.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Eric B Munson <ebmunson@us.ibm.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: David Rientjes <rientjes@google.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 9617729941 ("Drop free_pages()")
modified nr_free_pages() to return 'unsigned long' instead of 'unsigned
int'. This made the casts to 'unsigned long' in most callers superfluous,
so remove them.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Kyle McMartin <kyle@mcmartin.ca>
Acked-by: WANG Cong <xiyou.wangcong@gmail.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Haavard Skinnemoen <hskinnemoen@atmel.com>
Cc: Mikael Starvik <starvik@axis.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: David Howells <dhowells@redhat.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Chris Zankel <zankel@tensilica.com>
Cc: Michal Simek <monstr@monstr.eu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Bye-bye Performance Counters, welcome Performance Events!
In the past few months the perfcounters subsystem has grown out its
initial role of counting hardware events, and has become (and is
becoming) a much broader generic event enumeration, reporting, logging,
monitoring, analysis facility.
Naming its core object 'perf_counter' and naming the subsystem
'perfcounters' has become more and more of a misnomer. With pending
code like hw-breakpoints support the 'counter' name is less and
less appropriate.
All in one, we've decided to rename the subsystem to 'performance
events' and to propagate this rename through all fields, variables
and API names. (in an ABI compatible fashion)
The word 'event' is also a bit shorter than 'counter' - which makes
it slightly more convenient to write/handle as well.
Thanks goes to Stephane Eranian who first observed this misnomer and
suggested a rename.
User-space tooling and ABI compatibility is not affected - this patch
should be function-invariant. (Also, defconfigs were not touched to
keep the size down.)
This patch has been generated via the following script:
FILES=$(find * -type f | grep -vE 'oprofile|[^K]config')
sed -i \
-e 's/PERF_EVENT_/PERF_RECORD_/g' \
-e 's/PERF_COUNTER/PERF_EVENT/g' \
-e 's/perf_counter/perf_event/g' \
-e 's/nb_counters/nb_events/g' \
-e 's/swcounter/swevent/g' \
-e 's/tpcounter_event/tp_event/g' \
$FILES
for N in $(find . -name perf_counter.[ch]); do
M=$(echo $N | sed 's/perf_counter/perf_event/g')
mv $N $M
done
FILES=$(find . -name perf_event.*)
sed -i \
-e 's/COUNTER_MASK/REG_MASK/g' \
-e 's/COUNTER/EVENT/g' \
-e 's/\<event\>/event_id/g' \
-e 's/counter/event/g' \
-e 's/Counter/Event/g' \
$FILES
... to keep it as correct as possible. This script can also be
used by anyone who has pending perfcounters patches - it converts
a Linux kernel tree over to the new naming. We tried to time this
change to the point in time where the amount of pending patches
is the smallest: the end of the merge window.
Namespace clashes were fixed up in a preparatory patch - and some
stylistic fallout will be fixed up in a subsequent patch.
( NOTE: 'counters' are still the proper terminology when we deal
with hardware registers - and these sed scripts are a bit
over-eager in renaming them. I've undone some of that, but
in case there's something left where 'counter' would be
better than 'event' we can undo that on an individual basis
instead of touching an otherwise nicely automated patch. )
Suggested-by: Stephane Eranian <eranian@google.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Paul Mackerras <paulus@samba.org>
Reviewed-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: <linux-arch@vger.kernel.org>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Tim Abbott <tabbott@ksplice.com>
Acked-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Replace the use of CROSS_COMPILE to select a customized
installkernel script with the possibility to set INSTALLKERNEL
to select a custom installkernel script when running make:
make INSTALLKERNEL=arm-installkernel install
With this patch we are now more consistent across
different architectures - they did not all support use
of CROSS_COMPILE.
The use of CROSS_COMPILE was a hack as this really belongs
to gcc/binutils and the installkernel script does not change
just because we change toolchain.
The use of CROSS_COMPILE caused troubles with an upcoming patch
that saves CROSS_COMPILE when a kernel is built - it would no
longer be installable.
[Thanks to Peter Z. for this hint]
This patch undos what Ian did in commit:
0f8e2d62fa
("use ${CROSS_COMPILE}installkernel in arch/*/boot/install.sh")
The patch has been lightly tested on x86 only - but all changes
looks obvious.
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Mike Frysinger <vapier@gentoo.org> [blackfin]
Acked-by: Russell King <linux@arm.linux.org.uk> [arm]
Acked-by: Paul Mundt <lethal@linux-sh.org> [sh]
Acked-by: "H. Peter Anvin" <hpa@zytor.com> [x86]
Cc: Ian Campbell <icampbell@arcom.com>
Cc: Tony Luck <tony.luck@intel.com> [ia64]
Cc: Fenghua Yu <fenghua.yu@intel.com> [ia64]
Cc: Hirokazu Takata <takata@linux-m32r.org> [m32r]
Cc: Geert Uytterhoeven <geert@linux-m68k.org> [m68k]
Cc: Kyle McMartin <kyle@mcmartin.ca> [parisc]
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> [powerpc]
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> [s390]
Cc: Thomas Gleixner <tglx@linutronix.de> [x86]
Cc: Ingo Molnar <mingo@redhat.com> [x86]
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gerg/m68knommu: (53 commits)
m68knommu: Make PAGE_SIZE available to assembly files.
m68knommu: fix ColdFire definition of CLOCK_TICK_RATE
m68knommu: set multi-function pins for ethernet when enabled
m68knommu: remove special interrupt handling code for ne2k support
m68knommu: relax IO_SPACE_LIMIT setting
m68knommu: remove ColdFire direct interrupt register access
m68knommu: create a speciailized ColdFire 5272 interrupt controller
m68knommu: add support for second interrupt controller of ColdFire 5249
m68knommu: clean up old ColdFire timer irq setup
m68knommu: map ColdFire interrupts to correct masking bits
m68knommu: clean up ColdFire 532x CPU timer setup
m68knommu: simplify ColdFire "timers" clock initialization
m68knommu: support code to mask external interrupts on old ColdFire CPU's
m68knommu: merge old ColdFire interrupt controller masking macros
m68knommu: remove duplicate ColdFire mcf_autovector() code
m68knommu: move ColdFire INTC definitions to new include file
m68knommu: mask off all interrupts in ColdFire intc-simr controller
m68knommu: remove timer device interrupt setup for ColdFire 532x
m68knommu: remove interrupt masking from ColdFire pit timer
m68knommu: remove unecessary interrupt level setting in ColdFire 520x setup
...
The good definition of CLOCK_TICK_RATE for coldfires has been lost in the
merge of m68k and m68knommu include files. Restore it. Culprit :
commit ebafc17468
Signed-off-by: Philippe De Muyter <phdm@macqel.be>
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
The improved interrupt support for ColdFire CPU cores means we no
longer need all the interrupt setup and ack hacks to support the NE2000
driver on ColdFire platforms. Remove all that code.
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
There is really no limit to the addresses which can be used by the
in*() and out*() family of IO space calls in m68k non-MMU environments.
So don't impose an artificial address limit, allow the full 32bit range.
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
The ColdFire 5272 CPU has a very different interrupt controller than
any of the other ColdFire parts. It needs its own controller code to
correctly setup and ack interrupts.
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
The ColdFire 5249 CPU has a second (compleletly different) interrupt
controller. It is the only ColdFire CPU that has this type. It controlls
GPIO interrupts amongst a number of interrupts from other internal
peripherals. Add support code for it.
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
The older simple ColdFire interrupt controller has no one-to-one mapping
of interrupt numbers to bits in the interrupt mask register. Create a
mapping array that each ColdFire CPU type can populate with its available
interrupts and the bits that each use in the interrupt mask register.
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
The newer ColdFire 532x family of CPU's uses the old timer, but has a
newer interrupt controller. It doesn't need the special timer setup
that was required when using the older interrupt controller. Remove the
dead timer irq and level setting code, and define the hard coded vector.
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
The ColdFire "timers" clock setup can be simplified. There is really no
need for the flexible per-platform setup code. The clock interrupt can be
hard defined per CPU platform (in CPU include files). This makes the
actual timer code simpler.
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Currently the code that supports setting the old style ColdFire interrupt
controller mask registers is macros in the include files of each of the
CPU types. Merge all these into a set of real masking functions in the
old Coldfire interrupt controller code proper. All the macros are basically
the same (excepting a register size difference on really early parts).
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Create an mcfintc.h include file with the definitions for the old style
ColdFire interrupt controller. They are only needed on CPU's that use
this old controller - so isolate them on their own.
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
The ColdFire intc-simr interrupt controller should mask off all
interrupt sources at init time. Doing it here instead of separately
in each platform setup.
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
With proper interrupt controller code in place there is no need for
devices like the timers to have custom interrupt masking code.
Remove it (and the defines that go along with it).
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
The ColdFire 532x family of parts uses 2 of the same INTC interrupt
controlers used in the ColdFire 520x family. So modify the code to
support both parts. The extra code for the second INTC controler in
the case of the 520x is easily optimized away to nothing.
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Create general interrupt controller code for the ColdFire 520x family,
that does proper masking and unmasking of interrupts. With this in
place some of the driver hacks in place to support ColdFire interrupts
can finally go away.
Within the ColdFire family there is a variety of different interrupt
controllers in use. Some are used on multiple parts, some on only one.
There is quite some differences in some varients, so much so that
common code for all ColdFire parts would be impossible.
This commit introduces code to support one of the newer interrupt
controllers in the ColdFire 5208 and 5207 parts. It has very simple
mask and unmask operations, so is one of the easiest to support.
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
The non-mmu version of dma.h contains a lot of ColdFire specific DMA
support, but also all of the base m68k support. So use the non-mmu
version of dma.h for all.
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
It is reasonably strait forward to merge the mmu and non-mmu versions
of irq.h. Most of the defines and structs are not needed on non-mmu.
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
The mmu and non-mmu versions of processor.h have a lot of common code.
This is a strait forward merge. start_thread() could be improved, but
that is not quite as strait forward, leaving for a follow on change.
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: (46 commits)
powerpc64: convert to dynamic percpu allocator
sparc64: use embedding percpu first chunk allocator
percpu: kill lpage first chunk allocator
x86,percpu: use embedding for 64bit NUMA and page for 32bit NUMA
percpu: update embedding first chunk allocator to handle sparse units
percpu: use group information to allocate vmap areas sparsely
vmalloc: implement pcpu_get_vm_areas()
vmalloc: separate out insert_vmalloc_vm()
percpu: add chunk->base_addr
percpu: add pcpu_unit_offsets[]
percpu: introduce pcpu_alloc_info and pcpu_group_info
percpu: move pcpu_lpage_build_unit_map() and pcpul_lpage_dump_cfg() upward
percpu: add @align to pcpu_fc_alloc_fn_t
percpu: make @dyn_size mandatory for pcpu_setup_first_chunk()
percpu: drop @static_size from first chunk allocators
percpu: generalize first chunk allocator selection
percpu: build first chunk allocators selectively
percpu: rename 4k first chunk allocator to page
percpu: improve boot messages
percpu: fix pcpu_reclaim() locking
...
Fix trivial conflict as by Tejun Heo in kernel/sched.c
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6: (1623 commits)
netxen: update copyright
netxen: fix tx timeout recovery
netxen: fix file firmware leak
netxen: improve pci memory access
netxen: change firmware write size
tg3: Fix return ring size breakage
netxen: build fix for INET=n
cdc-phonet: autoconfigure Phonet address
Phonet: back-end for autoconfigured addresses
Phonet: fix netlink address dump error handling
ipv6: Add IFA_F_DADFAILED flag
net: Add DEVTYPE support for Ethernet based devices
mv643xx_eth.c: remove unused txq_set_wrr()
ucc_geth: Fix hangs after switching from full to half duplex
ucc_geth: Rearrange some code to avoid forward declarations
phy/marvell: Make non-aneg speed/duplex forcing work for 88E1111 PHYs
drivers/net/phy: introduce missing kfree
drivers/net/wan: introduce missing kfree
net: force bridge module(s) to be GPL
Subject: [PATCH] appletalk: Fix skb leak when ipddp interface is not loaded
...
Fixed up trivial conflicts:
- arch/x86/include/asm/socket.h
converted to <asm-generic/socket.h> in the x86 tree. The generic
header has the same new #define's, so that works out fine.
- drivers/net/tun.c
fix conflict between 89f56d1e9 ("tun: reuse struct sock fields") that
switched over to using 'tun->socket.sk' instead of the redundantly
available (and thus removed) 'tun->sk', and 2b980dbd ("lsm: Add hooks
to the TUN driver") which added a new 'tun->sk' use.
Noted in 'next' by Stephen Rothwell.
The definition of MCFSIM_PADDR and MCFSIM_PADAT now has MCF_BAR already added in.
Signed-off-by: Steven King <sfking@fdwdc.com>
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
This adds the basic infrastructure used by all of the different Coldfire CPUs.
Signed-off-by: Steven King <sfking@fdwdc.com>
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
In order to be able to use asm-offsets.h in C files the
existing namespace conflicts must be solved first. In
asm-offsets.h there are defines for signal constants, so they
can be used in assembler files.
Unfortunately the existing defines use a 1:1 mapping for the
macro names which results in name space conflicts if the header
file would also be used in C files. So rename the created
defines and add an "L" prefix to each one since that has
already been done for the SIGTRAP define in entry_mm.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Horst Hartmann <horsth@linux.vnet.ibm.com>
Cc: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: David Miller <davem@davemloft.net>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: <linux-arch@vger.kernel.org>
LKML-Reference: <20090831124416.998821502@de.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Neil Horman