Trusty update to 3.16.7-ckt20 stable release

SRU Justification

    Impact:
       The upstream process for stable tree updates is quite similar
       in scope to the Ubuntu SRU process, e.g., each patch has to
       demonstrably fix a bug, and each patch is vetted by upstream
       by originating either directly from Linus' tree or in a minimally
       backported form of that patch. The 3.16.7-ckt20 upstream stable
       patch set is now available. It should be included in the Ubuntu
       kernel as well.

       git://kernel.ubuntu.com/ubuntu/linux.git

    TEST CASE: TBD

       The following patches are in the 3.16.7-ckt20 stable release:
regmap: debugfs: Ensure we don't underflow when printing access masks
regmap: debugfs: Don't bother actually printing when calculating max length
x86/xen: Support kexec/kdump in HVM guests by doing a soft reset
s390/boot/decompression: disable floating point in decompressor
svcrdma: handle rdma read with a non-zero initial page offset
dm: fix AB-BA deadlock in __dm_destroy()
[SMB3] Do not fall back to SMBWriteX in set_file_size error cases
clk: ti: fix dual-registration of uart4_ick
ASoC: dwc: correct irq clear method
dm raid: fix round up of default region size
ALSA: hda: Add dock support for ThinkPad T550
ALSA: hda - Apply SPDIF pin ctl to MacBookPro 12,1
USB: Add reset-resume quirk for two Plantronics usb headphones.
usb: Add device quirk for Logitech PTZ cameras
staging: speakup: fix speakup-r regression
ALSA: synth: Fix conflicting OSS device registration on AWE32
arm64: readahead: fault retry breaks mmap file read random detection
sched/core: Fix TASK_DEAD race in finish_task_switch()
dm cache: fix NULL pointer when switching from cleaner policy
3w-9xxx: don't unmap bounce buffered commands
workqueue: make sure delayed work run in local cpu
drm/radeon: add pm sysfs files late
crypto: sparc - initialize blkcipher.ivsize
drm/nouveau/fbcon: take runpm reference when userspace has an open fd
crypto: ahash - ensure statesize is non-zero
dm thin: fix missing pool reference count decrement in pool_ctr error path
btrfs: check unsupported filters in balance arguments
btrfs: fix use after free iterating extrefs
i2c: rcar: enable RuntimePM before registering to the core
i2c: s3c2410: enable RuntimePM before registering to the core
i2c: designware-platdrv: enable RuntimePM before registering to the core
i2c: designware: Do not use parameters from ACPI on Dell Inspiron 7348
btrfs: fix possible leak in btrfs_ioctl_balance()
drm: Reject DRI1 hw lock ioctl functions for kms drivers
usb: xhci: Add support for URB_ZERO_PACKET to bulk/sg transfers
rbd: fix double free on rbd_dev->header_name
ath9k: declare required extra tx headroom
iio: accel: sca3000: memory corruption in sca3000_read_first_n_hw_rb()
iwlwifi: dvm: fix D3 firmware PN programming
iwlwifi: mvm: fix D3 firmware PN programming
iwlwifi: fix firmware filename for 3160
iwlwifi: pci: add a few more PCI subvendor IDs for the 7265 series
ARM: orion: Fix DSA platform device after mvmdio conversion
xen-blkfront: check for null drvdata in blkback_changed (XenbusStateClosing)
iio: mxs-lradc: Fix temperature offset
ALSA: hda - Fix inverted internal mic on Lenovo G50-80
drm/i915: Deny wrapping an userptr into a framebuffer
x86/efi: Fix multiple GOP device support
ASoC: Add info callback for SX_TLV controls
xhci: don't finish a TD if we get a short transfer event mid TD
xhci: handle no ping response error properly
xhci: Add spurious wakeup quirk for LynxPoint-LP controllers
ASoC: wm8904: Correct number of EQ registers
drm/nouveau/gem: return only valid domain when there's only one
powerpc/rtas: Validate rtas.entry before calling enter_rtas()
mm: make sendfile(2) killable
rbd: don't leak parent_spec in rbd_dev_probe_parent()
rbd: prevent kernel stack blow up on rbd map
dm btree remove: fix a bug when rebalancing nodes after removal
dm btree: fix leak of bufio-backed block in btree_split_beneath error path
IB/cm: Fix rb-tree duplicate free and use-after-free
iwlwifi: mvm: init card correctly on ctkill exit check
module: Fix locking in symbol_put_addr()
crypto: api - Only abort operations on fatal signal
md/raid1: submit_bio_wait() returns 0 on success
md/raid10: submit_bio_wait() returns 0 on success
iommu/amd: Don't clear DTE flags when modifying it
i2c: mv64xxx: really allow I2C offloading
drm/radeon: don't try to recreate sysfs entries on resume
mvsas: Fix NULL pointer dereference in mvs_slot_task_free
Revert "ARM64: unwind: Fix PC calculation"
drm/radeon: Restore LCD backlight level on resume (>= R5xx)
drm/radeon: move bl encoder assignment into bl init
drm/radeon: fix dpms when driver backlight control is disabled
rbd: require stable pages if message data CRCs are enabled
md/raid5: fix locking in handle_stripe_clean_event()
Revert "md: allow a partially recovered device to be hot-added to an array."
ipv6: Fix IPsec pre-encap fragmentation check
ppp: fix pppoe_dev deletion condition in pppoe_release()
ipv6: gre: support SIT encapsulation
net/mlx4: Copy/set only sizeof struct mlx4_eqe bytes
serial: 8250_pci: Add support for 16 port Exar boards
serial: 8250_pci: Add support for 12 port Exar boards
serial: 8250_pci: Correct uartclk for xr17v35x expansion chips
isdn_ppp: Add checks for allocation failure in isdn_ppp_open()
ppp, slip: Validate VJ compression slot parameters completely
staging/dgnc: fix info leak in ioctl
power: bq24190_charger: suppress build warning
sfc: Fix memcpy() with const destination compiler warning.
sched/preempt: Rename PREEMPT_CHECK_OFFSET to PREEMPT_DISABLE_OFFSET
sched/preempt: Fix cond_resched_lock() and cond_resched_softirq()
Linux 3.16.7-ckt20

The following patch from 3.16.7-ckt20 was already applied to the LTS Utopic kernel:

arm64: errata: use KBUILD_CFLAGS_MODULE for erratum #843419