Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Pull ext4 bugfixes from Ted Ts'o:
 "Ext4 bug fixes for 3.17, to provide better handling of memory
  allocation failures, and to fix some journaling bugs involving
  journal checksums and FALLOC_FL_ZERO_RANGE"

* tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: fix same-dir rename when inline data directory overflows
  jbd2: fix descriptor block size handling errors with journal_csum
  jbd2: fix infinite loop when recovering corrupt journal blocks
  ext4: update i_disksize coherently with block allocation on error path
  ext4: fix transaction issues for ext4_fallocate and ext_zero_range
  ext4: fix incorect journal credits reservation in ext4_zero_range
  ext4: move i_size,i_disksize update routines to helper function
  ext4: fix BUG_ON in mb_free_blocks()
  ext4: propagate errors up to ext4_find_entry()'s callers

Pull device mapper fix from Mike Snitzer:
 "Fix a 3.17-rc1 regression introduced by switching the DM crypt target
  to using per-bio data"

* tag 'dm-3.17-fix' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
  dm crypt: fix access beyond the end of allocated space

Pull block layer fixes from Jens Axboe:
 "A smaller collection of fixes that have come up since the initial
  merge window pull request.  This contains:

   - error handling cleanup and support for larger than 16 byte cdbs in
     sg_io() from Christoph.  The latter just matches what bsg and
     friends support, sg_io() got left out in the merge.

   - an option for brd to expose partitions in /proc/partitions.  They
     are hidden by default for compat reasons.  From Dmitry Monakhov.

   - a few blk-mq fixes from me - killing a dead/unused flag, fix for
     merging happening even if turned off, and correction of a few
     comments.

   - removal of unnecessary ->owner setting in systemace.  From Michal
     Simek.

   - two related fixes for a problem with nesting freezing of queues in
     blk-mq.  One from Ming Lei removing an unecessary freeze operation,
     and another from Tejun fixing the nesting regression introduced in
     the merge window.

   - fix for a BUG_ON() at bio_endio time when protection info is
     attached and the IO has an error.  From Sagi Grimberg.

   - two scsi_ioctl bug fixes for regressions with scsi-mq from Tony
     Battersby.

   - a cfq weight update fix and subsequent comment update from Toshiaki
     Makita"

* 'for-linus' of git://git.kernel.dk/linux-block:
  cfq-iosched: Add comments on update timing of weight
  cfq-iosched: Fix wrong children_weight calculation
  block: fix error handling in sg_io
  fix regression in SCSI_IOCTL_SEND_COMMAND
  scsi-mq: fix requests that use a separate CDB buffer
  block: support > 16 byte CDBs for SG_IO
  block: cleanup error handling in sg_io
  brd: add ram disk visibility option
  block: systemace: Remove .owner field for driver
  blk-mq: blk_mq_freeze_queue() should allow nesting
  blk-mq: correct a few wrong/bad comments
  block: Fix BUG_ON when pi errors occur
  blk-mq: don't allow merges if turned off for the queue
  blk-mq: get rid of unused BLK_MQ_F_SHOULD_SORT flag
  blk-mq: fix WARNING "percpu_ref_kill() called more than once!"

write{b,w,l,q}_relaxed are implemented by some architectures in order to
permit memory-mapped I/O writes with weaker barrier semantics than the
non-relaxed variants.

This patch implements these write macros for Alpha, in the same vein as
the relaxed read macros, which are already implemented.
Acked-by: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Matt Turner <mattst88@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: Michael Cree <mcree@orcon.net.nz>
Signed-off-by: Matt Turner <mattst88@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

When performing a same-directory rename, it's possible that adding or
setting the new directory entry will cause the directory to overflow
the inline data area, which causes the directory to be converted to an
extent-based directory.  Under this circumstance it is necessary to
re-read the directory when deleting the old dirent because the "old
directory" context still points to i_block in the inode table, which
is now an extent tree root!  The delete fails with an FS error, and
the subsequent fsck complains about incorrect link counts and
hardlinked directories.

Test case (originally found with flat_dir_test in the metadata_csum
test program):

# mkfs.ext4 -O inline_data /dev/sda
# mount /dev/sda /mnt
# mkdir /mnt/x
# touch /mnt/x/changelog.gz /mnt/x/copyright /mnt/x/README.Debian
# sync
# for i in /mnt/x/*; do mv $i $i.longer; done
# ls -la /mnt/x/
total 0
-rw-r--r-- 1 root root 0 Aug 25 12:03 changelog.gz.longer
-rw-r--r-- 1 root root 0 Aug 25 12:03 copyright
-rw-r--r-- 1 root root 0 Aug 25 12:03 copyright.longer
-rw-r--r-- 1 root root 0 Aug 25 12:03 README.Debian.longer

(Hey!  Why are there four files now??)
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org

It turns out that there are some serious problems with the on-disk
format of journal checksum v2.  The foremost is that the function to
calculate descriptor tag size returns sizes that are too big.  This
causes alignment issues on some architectures and is compounded by the
fact that some parts of jbd2 use the structure size (incorrectly) to
determine the presence of a 64bit journal instead of checking the
feature flags.

Therefore, introduce journal checksum v3, which enlarges the
descriptor block tag format to allow for full 32-bit checksums of
journal blocks, fix the journal tag function to return the correct
sizes, and fix the jbd2 recovery code to use feature flags to
determine 64bitness.

Add a few function helpers so we don't have to open-code quite so
many pieces.

Switching to a 16-byte block size was found to increase journal size
overhead by a maximum of 0.1%, to convert a 32-bit journal with no
checksumming to a 32-bit journal with checksum v3 enabled.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reported-by: TR Reardon <thomas_reardon@hotmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org

When recovering the journal, don't fall into an infinite loop if we
encounter a corrupt journal block.  Instead, just skip the block and
return an error, which fails the mount and thus forces the user to run
a full filesystem fsck.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org

In case of delalloc block i_disksize may be less than i_size. So we
have to update i_disksize each time we allocated and submitted some
blocks beyond i_disksize.  We weren't doing this on the error paths,
so fix this.

testcase: xfstest generic/019
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org

The DM crypt target accesses memory beyond allocated space resulting in
a crash on 32 bit x86 systems.

This bug is very old (it dates back to 2.6.25 commit 3a7f6c99 "dm
crypt: use async crypto").  However, this bug was masked by the fact
that kmalloc rounds the size up to the next power of two.  This bug
wasn't exposed until 3.17-rc1 commit 298a9fa0 ("dm crypt: use per-bio
data").  By switching to using per-bio data there was no longer any
padding beyond the end of a dm-crypt allocated memory block.

To minimize allocation overhead dm-crypt puts several structures into one
block allocated with kmalloc.  The block holds struct ablkcipher_request,
cipher-specific scratch pad (crypto_ablkcipher_reqsize(any_tfm(cc))),
struct dm_crypt_request and an initialization vector.

The variable dmreq_start is set to offset of struct dm_crypt_request
within this memory block.  dm-crypt allocates the block with this size:
cc->dmreq_start + sizeof(struct dm_crypt_request) + cc->iv_size.

When accessing the initialization vector, dm-crypt uses the function
iv_of_dmreq, which performs this calculation: ALIGN((unsigned long)(dmreq
+ 1), crypto_ablkcipher_alignmask(any_tfm(cc)) + 1).

dm-crypt allocated "cc->iv_size" bytes beyond the end of dm_crypt_request
structure.  However, when dm-crypt accesses the initialization vector, it
takes a pointer to the end of dm_crypt_request, aligns it, and then uses
it as the initialization vector.  If the end of dm_crypt_request is not
aligned on a crypto_ablkcipher_alignmask(any_tfm(cc)) boundary the
alignment causes the initialization vector to point beyond the allocated
space.

Fix this bug by calculating the variable iv_size_padding and adding it
to the allocated size.

Also correct the alignment of dm_crypt_request.  struct dm_crypt_request
is specific to dm-crypt (it isn't used by the crypto subsystem at all),
so it is aligned on __alignof__(struct dm_crypt_request).

Also align per_bio_data_size on ARCH_KMALLOC_MINALIGN, so that it is
aligned as if the block was allocated with kmalloc.
Reported-by: Krzysztof Kolasa <kkolasa@winsoft.pl>
Tested-by: Milan Broz <gmazyland@gmail.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Pull backlight fix from Lee Jones:
 "One simple fix to invalidate GPIO non-request"

* tag 'backlight-fixes-3.17' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight:
  pwm-backlight: Fix bogus request for GPIO#0 when instantiated from DT

Pull mfd fixes from Lee Jones:
 "Couple of simple fixes due for the 3.17 rcs

  (and a sneaky document addition that slipped from the previous
  pull-request)"

* tag 'mfd-fixes-3.17' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/mfd:
  mfd: twl4030-power: Fix PM idle pin configuration to not conflict with regulators
  mfd: tc3589x: Add device tree bindings
  mfd: ab8500-core: Use 'ifdef' for config options
  mfd: htc-i2cpld: Fix %d confusingly prefixed with 0x in format string
  mfd: omap-usb-host: Fix %d confusingly prefixed with 0x in format string

Pull pin-control fixes from Linus Walleij:
 "My first (a bit delayed) pack of pin control fixes for the v3.17
  series, only driver fixes:

   - SH-PFC (Renesas) r8a7791 CAN bus pin group problem
   - Rockchip (GPIO0 configuration)
   - Tegra-xusb (interrupt handling)
   - Exynos (GPIO interrupt locking)
   - Qualcomm (fix misleading example interrupts)
   - minor non-critical fixes for abx500 and AT91 also sneaked in,
     because I initially intended this pull for post RC-1, hope it's
     still OK"

* tag 'pinctrl-v3.17-2' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl:
  pinctrl: qcom: apq8064: Correct interrupts in example
  pinctrl: exynos: Lock GPIOs as interrupts when used as EINTs
  pinctrl: pinctrl-at91.c: fix decimal printf format specifiers prefixed with 0x
  pinctrl: abx500: remove useless check
  pinctrl: tegra-xusb: testing wrong variable in probe()
  pinctrl: tegra-xusb: fix an off by one test
  pinctrl: rockchip: fix rk3288 gpio0 configuration
  sh-pfc: r8a7791: fix CAN pin groups

Pull dma-buf fixes from Sumit Semwal:
 "The major changes for 3.17 already went via Greg-KH's tree this time
  as well; this is a small pull request for dma-buf - all documentation
  related"

* tag 'for-3.17-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/sumits/dma-buf:
  dma-buf/fence: Fix one more kerneldoc warning
  dma-buf/fence: Fix a kerneldoc warning
  Documentation/dma-buf-sharing.txt: update API descriptions

Pull sound fixes from Takashi Iwai:
 "Here contains not many exciting changes but just a few minor ones: An
  off-by-one proc write fix, a couple of trivial incldue guard fixes,
  Acer laptop pinconfig fix, and a fix for DSD formats that are still
  rarely used"

* tag 'sound-3.17-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound:
  ALSA: hda - Set up initial pins for Acer Aspire V5
  ALSA: pcm: Fix the silence data for DSD formats
  ALSA: ctxfi: ct20k1reg: Fix typo in include guard
  ALSA: hda: ca0132_regs.h: Fix typo in include guard
  ALSA: core: fix buffer overflow in snd_info_get_line()

Pull drm fixes from Dave Airlie:
 "Nothing major, one core oops fixes, some radeon oops fixes, some sti
  driver fixups, msm driver fixes and a minor Kconfig update for the ww
  mutex debugging"

* 'drm-fixes' of git://people.freedesktop.org/~airlied/linux:
  drm/ast: Add missing entry to dclk_table[]
  drm: fix division-by-zero on dumb_create()
  ww-mutex: clarify help text for DEBUG_WW_MUTEX_SLOWPATH
  radeon: Test for PCI root bus before assuming bus->self
  drm/radeon: handle broken disabled rb mask gracefully (6xx/7xx) (v2)
  drm/radeon: save/restore the PD addr on suspend/resume
  drm/msm: Fix missing unlock on error in msm_fbdev_create()
  drm/msm: fix compile error for non-dt builds
  drm/msm/mdp4: request vblank during modeset
  drm/msm: avoid flood of kernel logs on faults
  drm: sti: Add missing dependency on RESET_CONTROLLER
  drm: sti: Make of_device_id array const
  drm: sti: Fix return value check in sti_drm_platform_probe()
  drm: sti: hda: fix return value check in sti_hda_probe()
  drm: sti: hdmi: fix return value check in sti_hdmi_probe()
  drm: sti: tvout: fix return value check in sti_tvout_probe()

Commit 43fef47f (mfd: twl4030-power: Add a configuration to turn
off oscillator during off-idle) added support for configuring the PMIC
to cut off resources during deeper idle states to save power.

This however caused regression for n900 display power that needed the
PMIC configuration to be disabled with commit d937678a (ARM: dts:
Revert enabling of twl configuration for n900).

Turns out the root cause of the problem is that we must use
TWL4030_RESCONFIG_UNDEF instead of DEV_GRP_NULL to avoid disabling
regulators that may have been enabled before the init function
for twl4030-power.c runs. With TWL4030_RESCONFIG_UNDEF we let the
regulator framework control the regulators like it should. Here we
need to only configure the sys_clken and sys_off_mode triggers for
the regulators that cannot be done by the regulator framework as
it's not running at that point.

This allows us to enable the PMIC configuration for n900.

Fixes: 43fef47f (mfd: twl4030-power: Add a configuration to turn off oscillator during off-idle)

Cc: stable@vger.kernel.org # v3.16
Signed-off-by: Tony Lindgren <tony@atomide.com>
Tested-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

This defines the device tree bindings for the Toshiba TC3589x
series of multi-purpose expanders. Only the stuff I can test
is defined: GPIO and keypad. Others may implement more
subdevices further down the road.

This is to complement
commit a435ae1d
"mfd: Enable the tc3589x for Device Tree" which left off
the definition of the device tree bindings.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

Explain that weight has to be updated on activation.
This complements previous fix e15693ef ("cfq-iosched: Fix wrong
children_weight calculation").
Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Signed-off-by: Jens Axboe <axboe@fb.com>

The seqno_fence_init() function's cond argument isn't described in the
kerneldoc comment. Fix that to silence a warning when building DocBook
documentation.
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>

kerneldoc doesn't know how to parse variables, so don't let it try.
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>

Update some descriptions for API arguments and descriptions.
Signed-off-by: Gioh Kim <gioh.kim@lge.com>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>

This avoid reading past the end of the list for certain modes
Signed-off-by: Y.C. Chen <yc_chen@aspeedtech.com>
Reviewed-by: Egbert Eich <eich@freedesktop.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>

Merge branch 'drm-3.17-rc2-sti-fixes' of git://git.linaro.org/people/benjamin.gaignard/kernel into drm-fixes

I have tested the 6 patches send on mailing list since you merge the sti driver.
I haven't seen issue with those patches except for the missing
dependency on Kconfig
where I have change "depends on" to "select".

* 'drm-3.17-rc2-sti-fixes' of git://git.linaro.org/people/benjamin.gaignard/kernel:
  drm: sti: Add missing dependency on RESET_CONTROLLER
  drm: sti: Make of_device_id array const
  drm: sti: Fix return value check in sti_drm_platform_probe()
  drm: sti: hda: fix return value check in sti_hda_probe()
  drm: sti: hdmi: fix return value check in sti_hdmi_probe()
  drm: sti: tvout: fix return value check in sti_tvout_probe()

misc msm fixes from Rob.

* 'msm-fixes-3.17' of git://people.freedesktop.org/~robclark/linux:
  drm/msm: Fix missing unlock on error in msm_fbdev_create()
  drm/msm: fix compile error for non-dt builds
  drm/msm/mdp4: request vblank during modeset
  drm/msm: avoid flood of kernel logs on faults

Kinda unexpected, but DIV_ROUND_UP() can overflow if passed an argument
bigger than UINT_MAX - DIVISOR. Fix this by testing for "!cpp" before
using it in the following division.

Note that DIV_ROUND_UP() is defined as:
        #define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))

..this will obviously overflow if (n + d - 1) is bigger than UINT_MAX.
Reported-by: Tommi Rantala <tt.rantala@gmail.com>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

We really don't want distro's enabling this in their kernels.  Try and
make that more clear.
Signed-off-by: Rob Clark <robdclark@gmail.com>
Acked-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

Just a few more radeon fixes for 3.17.

* 'drm-fixes-3.17' of git://people.freedesktop.org/~agd5f/linux:
  radeon: Test for PCI root bus before assuming bus->self
  drm/radeon: handle broken disabled rb mask gracefully (6xx/7xx) (v2)
  drm/radeon: save/restore the PD addr on suspend/resume

Pull tomoyo fix from Serge Hallyn.

* 'sec-v3.17-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/sergeh/linux-security:
  tomoyo: Fix pathname calculation breakage.

After commit f282ac19 we use different transactions for
preallocation and i_disksize update which result in complain from fsck
after power-failure.  spotted by generic/019. IMHO this is regression
because fs becomes inconsistent, even more 'e2fsck -p' will no longer
works (which drives admins go crazy) Same transaction requirement
applies ctime,mtime updates

testcase: xfstest generic/019
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org

Currently we reserve only 4 blocks but in worst case scenario
ext4_zero_partial_blocks() may want to zeroout and convert two
non adjacent blocks.
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org

If we assign a Radeon device to a virtual machine, we can no longer
assume a fixed hardware topology, like the GPU having a parent device.
This patch simply adds a few pci_is_root_bus() tests to avoid passing
a NULL pointer to PCI access functions, allowing the radeon driver to
work in a QEMU 440FX machine with an assigned HD8570 on the emulated
PCI root bus.
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Pull HID fixes from Jiri Kosina:

 - fixes for potential memory corruption problems in magicmouse and
   picolcd drivers (the HW would have to be manufactured to be
   deliberately evil to trigger those) which were found by Steven
   Vittitoe

 - fix for false error message appearing in dmesg from logitech-dj
   driver, from Benjamin Tissoires

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid:
  HID: picolcd: sanity check report size in raw_event() callback
  HID: magicmouse: sanity check report size in raw_event() callback
  HID: logitech-dj: prevent false errors to be shown

Pull btrfs fixes from Chris Mason:
 "The biggest of these comes from Liu Bo, who tracked down a hang we've
  been hitting since moving to kernel workqueues (it's a btrfs bug, not
  in the generic code).  His patch needs backporting to 3.16 and 3.15
  stable, which I'll send once this is in.

  Otherwise these are assorted fixes.  Most were integrated last week
  during KS, but I wanted to give everyone the chance to test the
  result, so I waited for rc2 to come out before sending"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs: (24 commits)
  Btrfs: fix task hang under heavy compressed write
  Btrfs: fix filemap_flush call in btrfs_file_release
  Btrfs: fix crash on endio of reading corrupted block
  btrfs: fix leak in qgroup_subtree_accounting() error path
  btrfs: Use right extent length when inserting overlap extent map.
  Btrfs: clone, don't create invalid hole extent map
  Btrfs: don't monopolize a core when evicting inode
  Btrfs: fix hole detection during file fsync
  Btrfs: ensure tmpfile inode is always persisted with link count of 0
  Btrfs: race free update of commit root for ro snapshots
  Btrfs: fix regression of btrfs device replace
  Btrfs: don't consider the missing device when allocating new chunks
  Btrfs: Fix wrong device size when we are resizing the device
  Btrfs: don't write any data into a readonly device when scrub
  Btrfs: Fix the problem that the replace destroys the seed filesystem
  btrfs: Return right extent when fiemap gives unaligned offset and len.
  Btrfs: fix wrong extent mapping for DirectIO
  Btrfs: fix wrong write range for filemap_fdatawrite_range()
  Btrfs: fix wrong missing device counter decrease
  Btrfs: fix unzeroed members in fs_devices when creating a fs from seed fs
  ...

Merge tag 'trace-fixes-v3.17-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull trace buffer epoll hang fix from Steven Rostedt:
 "Josef Bacik found a bug in the ring_buffer_poll_wait() where the
  condition variable (waiters_pending) was set before being added to the
  poll queue via poll_wait().  This allowed for a small race window to
  happen where an event could come in, check the condition variable see
  it set to true, clear it, and then wake all the waiters.  But because
  the waiter set the variable before adding itself to the queue, the
  waker could have cleared the variable after it was set and then miss
  waking it up as it wasn't added to the queue yet.

  Discussing this bug, we realized that a memory barrier needed to be
  added too, for the rare case that something polls for a single trace
  event to happen (and just one, no more to come in), and miss the
  wakeup due to memory ordering.  Ideally, a memory barrier needs to be
  added on the writer side too, but as that will kill tracing
  performance and this is for a situation that tracing wasn't even
  designed for (who traces one instance of an event, use a printk
  instead!), this isn't worth adding the barrier.  But we can in the
  future add the barrier for when the buffer goes from empty to the
  first event, as that would cover this case"

* tag 'trace-fixes-v3.17-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  trace: Fix epoll hang when we race with new entries