This patch fixes a kernel Oops in the GFS2 rename code.

The problem was in the way the gfs2 directory code was trying
to re-use sentinel directory entries.

In the failing case, gfs2's rename function was renaming a
file to another name that had the same non-trivial length.
The file being renamed happened to be the first directory
entry on the leaf block.

First, the rename code (gfs2_rename in ops_inode.c) found the
original directory entry and decided it could do its job by
simply replacing the directory entry with another.  Therefore
it determined correctly that no block allocations were needed.

Next, the rename code deleted the old directory entry prior to
replacing it with the new name.  Therefore, the soon-to-be
replaced directory entry was temporarily made into a directory
entry "sentinel" or a place holder at the start of a leaf block.

Lastly, it went to re-add the replacement directory entry in
that leaf block.  However, when gfs2_dirent_find_space was
looking for space in the leaf block, it used the wrong value
for the sentinel.  That threw off its calculations so later
it decides it can't really re-use the sentinel and therefore
must allocate a new leaf block.  But because it previously decided
to re-use the directory entry, it didn't waste the time to
grab a new block allocation for the inode.  Therefore, the
inode's i_alloc pointer was still NULL and it crashes trying to
reference it.

In the case of sentinel directory entries, the entire dirent is
reused, not just the "free space" portion of it, and therefore
the function gfs2_dirent_find_space should use the value 0
rather than GFS2_DIRENT_SIZE(0) for the actual dirent size.

Fixing this calculation enables the reproducer programs to work
properly.
Signed-off-by: NBob Peterson <rpeterso@redhat.com>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

HighMem pages on i686 do not get mapped to the buffer_heads and this was
causing a NULL pointer dereference when we were trying to memset page buffers
to zero.
We now use zero_user() that kmaps the page and directly manipulates page data.
This patch also fixes a boundary condition that was incorrect.
Signed-off-by: NAbhi Das <adas@redhat.com>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

This patch fixes a problem in an error path when looking
up dinodes.  There are two sister-functions, gfs2_inode_lookup
and gfs2_process_unlinked_inode.  Both functions acquire and
hold the i_iopen glock for the dinode being looked up. The last
thing they try to do is hold the i_gl glock for the dinode.
If that glock fails for some reason, the error path was
incorrectly calling gfs2_glock_put for the i_iopen glock twice.
This resulted in the glock being prematurely freed.  The
"minimum hold time" usually kept the glock in memory, but the
lock interface to dlm (aka lock_dlm) freed its memory for the
glock.  In some circumstances, it would cause dlm's dlm_astd daemon
to try to call the bast function for the freed lock_dlm memory,
which resulted in a NULL pointer dereference.
Signed-off-by: NBob Peterson <rpeterso@redhat.com>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

This patch fixes bugzilla bug #590878: GFS2: recovery stuck on
transaction lock.  We set the frozen flag on the glock when we receive
a completion that cannot be delivered due to blocked locks. At that
point we check to see whether the first waiting holder has the noexp
flag set. If the noexp lock is queued later, then we need to unfreeze
the glock at that point in time, namely, in the glock work function.

This patch was originally written by Steve Whitehouse, but since
he's on holiday, I'm submitting it.  It's been well tested with a
complex recovery test called revolver.
Signed-off-by: NSteve Whitehouse <swhiteho@redhat.com>
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

This patch replaces a statement that got dropped out by accident.
Without the patch, truncates on stuffed (very small) files cause
those files to have an unpredictable size.
Signed-off-by: NBob Peterson <rpeterso@redhat.com>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

* master.kernel.org:/home/rmk/linux-2.6-arm:
  ARM: 6226/1: fix kprobe bug in ldr instruction emulation
  ARM: Update mach-types
  ARM: lockdep: fix unannotated irqs-on
  ARM: 6184/2: ux500: use neutral PRCMU base
  ARM: 6212/1: atomic ops: add memory constraints to inline asm
  ARM: 6211/1: atomic ops: fix register constraints for atomic64_add_unless
  ARM: 6210/1: Do not rely on reset defaults of L2X0_AUX_CTRL

* 'lmb-to-memblock' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc:
  lmb: rename to memblock

* 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc:
  powerpc/fsl-booke: Fix address issue when using relocatable kernels
  powerpc/cpm1: Mark micropatch code/data static and __init
  powerpc/cpm1: Fix build with various CONFIG_*_UCODE_PATCH combinations
  powerpc/cpm: Reintroduce global spi_pram struct (fixes build issue)

From: Bin Yang <bin.yang@marvell.com>

Cc: stable@kernel.org
Signed-off-by: NBin Yang <bin.yang@marvell.com>
Signed-off-by: NNicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

via following scripts

      FILES=$(find * -type f | grep -vE 'oprofile|[^K]config')

      sed -i \
        -e 's/lmb/memblock/g' \
        -e 's/LMB/MEMBLOCK/g' \
        $FILES

      for N in $(find . -name lmb.[ch]); do
        M=$(echo $N | sed 's/lmb/memblock/g')
        mv $N $M
      done

and remove some wrong change like lmbench and dlmb etc.

also move memblock.c from lib/ to mm/
Suggested-by: NIngo Molnar <mingo@elte.hu>
Acked-by: N"H. Peter Anvin" <hpa@zytor.com>
Acked-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NYinghai Lu <yinghai@kernel.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  input: i8042 - add runtime check in x86's i8042_platform_init
  Revert "Input: fixup X86_MRST selects"
  Revert "Input: do not force selecting i8042 on Moorestown"
  x86, mrst: Add i8042_detect API for Moorestwon platform
  x86: Add i8042 pre-detection hook to x86_platform_ops
  x86, platform: Export x86_platform to modules

* 'kvm-updates/2.6.35' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: MMU: flush remote tlbs when overwriting spte with different pfn
  KVM: VMX: Fix host MSR_KERNEL_GS_BASE corruption

* 'arm/defconfig/reduced-v2.6.35-rc1' of git://git.pengutronix.de/git/ukl/linux-2.6:
  ARM: reduce defconfigs

This is a big change, but results in no loss of information, despite us
losing almost 200k lines:

 177 files changed, 652 insertions(+), 194157 deletions(-)

and Grant Likely thinks powerpc can also use the same reduction
technique.

The python script that did the reduction looks like this:

    #! /usr/bin/env python
    # vim: set fileencoding=utf-8 :
    # Copyright (C) 2010 by Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

    import re
    import subprocess
    import os
    import sys

    # This prevents including a timestamp in the .config which makes comparing a
    # bit easier.
    os.environ['KCONFIG_NOTIMESTAMP'] = 'Yes, please'

    # XXX: get these using getopt
    kernel_tree = '' # os.path.join(os.environ['HOME'], 'gsrc', 'linux-2.6')
    arch = 'arm'
    target = sys.argv[1]
    defconfig_src = os.path.join(kernel_tree, 'arch/%s/configs/%s' % (arch, target))

    subprocess.check_call(['make', '-s', 'ARCH=%s' % arch, target])
    origconfig = list(open('.config'))
    config = list(origconfig)
    config_size = os.stat('.config').st_size

    i = 0

    while i < len(config):
        print 'test for %r' % config[i]
        defconfig = open(defconfig_src, 'w')
        defconfig.writelines(config[:i])
        defconfig.writelines(config[i + 1:])
        defconfig.close()
        subprocess.check_call(['make', '-s', 'ARCH=%s' % arch, target])
        if os.stat('.config').st_size == config_size and list(open('.config')) == origconfig:
            del config[i]
        else:
            i += 1

    defconfig = open(defconfig_src, 'w')
    defconfig.writelines(config)
    defconfig.close()

which is pretty self-explanatory.
Acked-by: NNicolas Pitre <nico@fluxnic.net>
Acked-by: NRussell King <linux@arm.linux.org.uk>
Acked-by: NGrant Likely <grant.likely@secretlab.ca>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

* 'fix/hda' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6:
  ALSA: hda - Restore cleared pin controls on resume

* 'v4l_for_2.6.35' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-2.6:
  V4L/DVB: uvc: Fix multiple symbols definitions with UVC gadget and host drivers
  V4L/DVB: v4l: mem2mem_testdev: fix g_fmt NULL pointer dereference
  V4L/DVB: uvcvideo: Power line frequency control doesn't support GET_MIN/MAX/RES
  V4L/DVB: ivtv: Add delay to ensure the decoder always restarts with a blank screen
  V4L/DVB: Documentation: Add the Philips FQ1236 MK5 to video4linux/CARDLIST.tuner
  V4L/DVB: tveeprom: Add an entry for tuner code 168: a TCL M30WTP-4N-E tuner
  V4L/DVB: tuner: Add a definition for the Philips FQ1236 MK5 NTSC tuner
  V4L/DVB: OMAP_VOUT: fix: Module params were not working through bootargs
  V4L/DVB: OMAP_VOUT: fix: Replaced dma-sg with dma-contig
  V4L/DVB: OMAP_VOUT:Build FIX: Rebased against latest DSS2 changes

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid:
  HID: Send Report ID when numbered reports are sent over the control endpoint.
  HID: Enable HID_QUIRK_MULTI_INPUT for Retro Adaptor
  HID: add support for CH Eclipse yoke
  HID: eliminate a double lock in debug code
  HID: ntrig: add support for new firwmare versions
  HID: check for HID_QUIRK_IGNORE during probing
  HID: roccat: fix modules interdependencies

File patterns are one per line.
Fixed include file location.
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

After remove a rmap, we should flush all vcpu's tlb
Signed-off-by: NXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

The Report ID wasn't sent as part of the payload for reports which were sent
over the control endpoint. This is required by section 8.1 of the HID spec.
Signed-off-by: NAlan Ott <alan@signal11.us>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

The UVC gadget driver borrowed code from the UVC host driver without
changing the symbol names. This results in a namespace clash with
multiple definitions of several symbols when compiling both drivers in
the kernel.

Make all generic UVC functions and variables static in the UVC gadget
driver, as the symbols are not referenced outside of the gadget driver.
Rename the uvc_trace_param global variable to uvc_gadget_trace_param.
Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

* 'hwmon-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jdelvare/staging:
  hwmon: Fix autoloading of fschmd on recent Fujitsu machines
  hwmon: (coretemp) Properly label the sensors
  hwmon: (coretemp) Skip duplicate CPU entries
  hwmon: (it87) Fix in7 on IT8720F
  hwmon: (k8temp) Fix temperature reporting for ASB1 processor revisions

* 'i2c-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jdelvare/staging:
  i2c/mips: Fix error return codes from Sibyte i2c bus driver
  i2c: Fix probability check

Patch for linux-2.6.35-rc4 mainline kernel to enable Paul Qureshi's
Retro Adapter [http://keio.dk/retroadapter.html], an open source USB
device which allows controllers and joysticks from classic computers
and consoles to work on modern PCs, to appear as two separate devices
under Linux.
Signed-off-by: NPeter Edwards <samwise@bagshot-row.org>
Acked-by: NPaul Qureshi <retro@world3.net>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

This USB flight yoke needs the NOGET quirk, like most of CH's other
products. This patch adds that.
Signed-off-by: NJonathan Rockway <jon@jrock.us>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

When booting a relocatable kernel it needs to jump to the correct
start address, which for BookE parts is usually unchanged
regardless of the physical memory offset.

Recent changes cause problems with how we calculate the start
address, it was always adding the RMO into the start address
which is incorrect. This patch only adds in the RMO offset
if we are in the kexec code path, as it needs the RMO to work
correctly.

Instead of adding the RMO offset in in the common code path, we
can just set r6 to the RMO offset in the kexec code path instead
of to zero, and finally perform the masking in the common code
path
Signed-off-by: NMatthew McClintock <msm@freescale.com>
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>

This saves runtime memory and fixes lots of sparse warnings like this:

    CHECK   arch/powerpc/sysdev/micropatch.c
  arch/powerpc/sysdev/micropatch.c:27:6: warning: symbol 'patch_2000'
  was not declared. Should it be static?
  arch/powerpc/sysdev/micropatch.c:146:6: warning: symbol 'patch_2f00'
  was not declared. Should it be static?
  ...
Signed-off-by: NAnton Vorontsov <avorontsov@mvista.com>
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>

Warnings are treated as errors for arch/powerpc code, so build fails
with CONFIG_I2C_SPI_UCODE_PATCH=y:

    CC      arch/powerpc/sysdev/micropatch.o
  cc1: warnings being treated as errors
  arch/powerpc/sysdev/micropatch.c: In function 'cpm_load_patch':
  arch/powerpc/sysdev/micropatch.c:630: warning: unused variable 'smp'
  make[1]: *** [arch/powerpc/sysdev/micropatch.o] Error 1

And with CONFIG_USB_SOF_UCODE_PATCH=y:

  CC      arch/powerpc/sysdev/micropatch.o
  cc1: warnings being treated as errors
  arch/powerpc/sysdev/micropatch.c: In function 'cpm_load_patch':
  arch/powerpc/sysdev/micropatch.c:629: warning: unused variable 'spp'
  arch/powerpc/sysdev/micropatch.c:628: warning: unused variable 'iip'
  make[1]: *** [arch/powerpc/sysdev/micropatch.o] Error 1

This patch fixes these issues by introducing proper #ifdefs.

Cc: <stable@kernel.org> [ .33, .34 ]
Signed-off-by: NAnton Vorontsov <avorontsov@mvista.com>
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>

spi_t was removed in commit 644b2a68
("powerpc/cpm: Remove SPI defines and spi structs"), the commit assumed
that spi_t isn't used anywhere outside of the spi_mpc8xxx driver. But
it appears that the struct is needed for micropatch code. So, let's
reintroduce the struct.

Fixes the following build issue:

    CC      arch/powerpc/sysdev/micropatch.o
  micropatch.c: In function 'cpm_load_patch':
  micropatch.c:629: error: expected '=', ',', ';', 'asm' or '__attribute__' before '*' token
  micropatch.c:629: error: 'spp' undeclared (first use in this function)
  micropatch.c:629: error: (Each undeclared identifier is reported only once
  micropatch.c:629: error: for each function it appears in.)
Reported-by: NLEROY Christophe <christophe.leroy@c-s.fr>
Reported-by: NTony Breeds <tony@bakeyournoodle.com>
Cc: <stable@kernel.org> [ .33, .34 ]
Signed-off-by: NAnton Vorontsov <avorontsov@mvista.com>
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>

CPU: Testing write buffer coherency: ok
------------[ cut here ]------------
WARNING: at kernel/lockdep.c:3145 check_flags+0xcc/0x1dc()
Modules linked in:
[<c0035120>] (unwind_backtrace+0x0/0xf8) from [<c0355374>] (dump_stack+0x20/0x24)
[<c0355374>] (dump_stack+0x20/0x24) from [<c0060c04>] (warn_slowpath_common+0x58/0x70)
[<c0060c04>] (warn_slowpath_common+0x58/0x70) from [<c0060c3c>] (warn_slowpath_null+0x20/0x24)
[<c0060c3c>] (warn_slowpath_null+0x20/0x24) from [<c008f224>] (check_flags+0xcc/0x1dc)
[<c008f224>] (check_flags+0xcc/0x1dc) from [<c00945dc>] (lock_acquire+0x50/0x140)
[<c00945dc>] (lock_acquire+0x50/0x140) from [<c0358434>] (_raw_spin_lock+0x50/0x88)
[<c0358434>] (_raw_spin_lock+0x50/0x88) from [<c00fd114>] (set_task_comm+0x2c/0x60)
[<c00fd114>] (set_task_comm+0x2c/0x60) from [<c007e184>] (kthreadd+0x30/0x108)
[<c007e184>] (kthreadd+0x30/0x108) from [<c0030104>] (kernel_thread_exit+0x0/0x8)
---[ end trace 1b75b31a2719ed1c ]---
possible reason: unannotated irqs-on.
irq event stamp: 3
hardirqs last  enabled at (2): [<c0059bb0>] finish_task_switch+0x48/0xb0
hardirqs last disabled at (3): [<c002f0b0>] ret_slow_syscall+0xc/0x1c
softirqs last  enabled at (0): [<c005f3e0>] copy_process+0x394/0xe5c
softirqs last disabled at (0): [<(null)>] (null)

Fix this by ensuring that the lockdep interrupt state is manipulated in
the appropriate places.  We essentially treat userspace as an entirely
separate environment which isn't relevant to lockdep (lockdep doesn't
monitor userspace.)  We don't tell lockdep that IRQs will be enabled
in that environment.

Instead, when creating kernel threads (which is a rare event compared
to entering/leaving userspace) we have to update the lockdep state.  Do
this by starting threads with IRQs disabled, and in the kthread helper,
tell lockdep that IRQs are enabled, and enable them.

This provides lockdep with a consistent view of the current IRQ state
in kernel space.

This also revert portions of 0d928b0b
which didn't fix the problem.
Tested-by: NMing Lei <tom.leiming@gmail.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Sibyte i2c bus driver returns non-descriptive error values.
Update to return error values as defined in Documentation/i2c/fault-codes.
Signed-off-by: NGuenter Roeck <guenter.roeck@ericsson.com>
Signed-off-by: NJean Delvare <khali@linux-fr.org>

The new unified probing function differs from the original code, and
the preliminary test whether probing is possible must be updated
accordingly.
Signed-off-by: NJean Delvare <khali@linux-fr.org>

Fujitsu slightly changed the DMI strings in their recent machines,
(for example the D2778) and this breaks the automatic loading of the
needed fschmd driver. Being more tolerant on string comparison fixes
the issue.

This closes bug #15634:
https://bugzilla.kernel.org/show_bug.cgi?id=15634Signed-off-by: NJean Delvare <khali@linux-fr.org>
Tested-by: NSergey Spiridonov <sena@hurd.homeunix.org>
Cc: Hans de Goede <hdegoede@redhat.com>

Don't assume that CPU entry number and core ID always match. It
worked in the simple cases (single CPU, no HT) but fails on
multi-CPU systems.
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Acked-by: NHuaxu Wan <huaxu.wan@intel.com>
Cc: stable@kernel.org

On hyper-threaded CPUs, each core appears twice in the CPU list. Skip
the second entry to avoid duplicate sensors.
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Acked-by: NHuaxu Wan <huaxu.wan@intel.com>
Cc: stable@kernel.org

The IT8720F has no VIN7 pin, so VCCH should always be routed
internally to VIN7 with an internal divider. Curiously, there still
is a configuration bit to control this, which means it can be set
incorrectly. And even more curiously, many boards out there are
improperly configured, even though the IT8720F datasheet claims that
the internal routing of VCCH to VIN7 is the default setting. So we
force the internal routing in this case.

It turns out that all boards with the wrong setting are from Gigabyte,
so I suspect a BIOS bug. But it's easy enough to workaround in the
driver, so let's do it.
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Cc: Jean-Marc Spaggiari <jean-marc@spaggiari.org>
Cc: stable@kernel.org

Reported temperature for ASB1 CPUs is too high.
Add ASB1 CPU revisions (these are also non-desktop variants) to the
list of CPUs for which the temperature fixup is not required.

Example: (from LENOVO ThinkPad Edge 13, 01972NG, system was idle)

  Current kernel reports

  $ sensors
  k8temp-pci-00c3
  Adapter: PCI adapter
  Core0 Temp:  +74.0 C
  Core0 Temp:  +70.0 C
  Core1 Temp:  +69.0 C
  Core1 Temp:  +70.0 C

  With this patch I have

  $ sensors
  k8temp-pci-00c3
  Adapter: PCI adapter
  Core0 Temp:  +54.0 C
  Core0 Temp:  +51.0 C
  Core1 Temp:  +48.0 C
  Core1 Temp:  +49.0 C

Cc: stable@kernel.org [.32.x .33.x, .34.x]
Cc: Rudolf Marek <r.marek@assembler.cz>
Signed-off-by: NAndreas Herrmann <andreas.herrmann3@amd.com>
Signed-off-by: NJean Delvare <khali@linux-fr.org>

The MTU wallclock timing fix-up patch was hardwired to the DB8500
causing a regression. This makes it work on the DB5500 as well.
Signed-off-by: NLinus Walleij <linus.walleij@stericsson.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Currently, the 32-bit and 64-bit atomic operations on ARM do not
include memory constraints in the inline assembly blocks. In the
case of barrier-less operations [for example, atomic_add], this
means that the compiler may constant fold values which have actually
been modified by a call to an atomic operation.

This issue can be observed in the atomic64_test routine in
<kernel root>/lib/atomic64_test.c:

00000000 <test_atomic64>:
   0:	e1a0c00d 	mov	ip, sp
   4:	e92dd830 	push	{r4, r5, fp, ip, lr, pc}
   8:	e24cb004 	sub	fp, ip, #4
   c:	e24dd008 	sub	sp, sp, #8
  10:	e24b3014 	sub	r3, fp, #20
  14:	e30d000d 	movw	r0, #53261	; 0xd00d
  18:	e3011337 	movw	r1, #4919	; 0x1337
  1c:	e34c0001 	movt	r0, #49153	; 0xc001
  20:	e34a1aa3 	movt	r1, #43683	; 0xaaa3
  24:	e16300f8 	strd	r0, [r3, #-8]!
  28:	e30c0afe 	movw	r0, #51966	; 0xcafe
  2c:	e30b1eef 	movw	r1, #48879	; 0xbeef
  30:	e34d0eaf 	movt	r0, #57007	; 0xdeaf
  34:	e34d1ead 	movt	r1, #57005	; 0xdead
  38:	e1b34f9f 	ldrexd	r4, [r3]
  3c:	e1a34f90 	strexd	r4, r0, [r3]
  40:	e3340000 	teq	r4, #0
  44:	1afffffb 	bne	38 <test_atomic64+0x38>
  48:	e59f0004 	ldr	r0, [pc, #4]	; 54 <test_atomic64+0x54>
  4c:	e3a0101e 	mov	r1, #30
  50:	ebfffffe 	bl	0 <__bug>
  54:	00000000 	.word	0x00000000

The atomic64_set (0x38-0x44) writes to the atomic64_t, but the
compiler doesn't see this, assumes the test condition is always
false and generates an unconditional branch to __bug. The rest of the
test is optimised away.

This patch adds suitable memory constraints to the atomic operations on ARM
to ensure that the compiler is informed of the correct data hazards. We have
to use the "Qo" constraints to avoid hitting the GCC anomaly described at
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44492 , where the compiler
makes assumptions about the writeback in the addressing mode used by the
inline assembly. These constraints forbid the use of auto{inc,dec} addressing
modes, so it doesn't matter if we don't use the operand exactly once.

Cc: stable@kernel.org
Reviewed-by: NNicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>