Successful RMW operations are supposed to be fully ordered, but
Alpha's xchg() and cmpxchg() do not meet this requirement.

Will Deacon noticed the bug:

  > So MP using xchg:
  >
  > WRITE_ONCE(x, 1)
  > xchg(y, 1)
  >
  > smp_load_acquire(y) == 1
  > READ_ONCE(x) == 0
  >
  > would be allowed.

... which thus violates the above requirement.

Fix it by adding a leading smp_mb() to the xchg() and cmpxchg() implementations.

Reported-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrea Parri <parri.andrea@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-alpha@vger.kernel.org
Link: http://lkml.kernel.org/r/1519291488-5752-1-git-send-email-parri.andrea@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Replace each occurrence of __ASM__MB with a (trailing) smp_mb() in
xchg(), cmpxchg(), and remove the now unused __ASM__MB definitions;
this improves readability, with no additional synchronization cost.

Suggested-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrea Parri <parri.andrea@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-alpha@vger.kernel.org
Link: http://lkml.kernel.org/r/1519291469-5702-1-git-send-email-parri.andrea@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Continuing along with the fight against smp_read_barrier_depends() [1]
(or rather, against its improper use), add an unconditional barrier to
cmpxchg.  This guarantees that dependency ordering is preserved when a
dependency is headed by an unsuccessful cmpxchg.  As it turns out, the
change could enable further simplification of LKMM as proposed in [2].

[1] https://marc.info/?l=linux-kernel&m=150884953419377&w=2
    https://marc.info/?l=linux-kernel&m=150884946319353&w=2
    https://marc.info/?l=linux-kernel&m=151215810824468&w=2
    https://marc.info/?l=linux-kernel&m=151215816324484&w=2

[2] https://marc.info/?l=linux-kernel&m=151881978314872&w=2

Signed-off-by: Andrea Parri <parri.andrea@gmail.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-alpha@vger.kernel.org
Link: http://lkml.kernel.org/r/1519152356-4804-1-git-send-email-parri.andrea@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Pull PCI updates from Bjorn Helgaas:

 - skip AER driver error recovery callbacks for correctable errors
   reported via ACPI APEI, as we already do for errors reported via the
   native path (Tyler Baicar)

 - fix DPC shared interrupt handling (Alex Williamson)

 - print full DPC interrupt number (Keith Busch)

 - enable DPC only if AER is available (Keith Busch)

 - simplify DPC code (Bjorn Helgaas)

 - calculate ASPM L1 substate parameter instead of hardcoding it (Bjorn
   Helgaas)

 - enable Latency Tolerance Reporting for ASPM L1 substates (Bjorn
   Helgaas)

 - move ASPM internal interfaces out of public header (Bjorn Helgaas)

 - allow hot-removal of VGA devices (Mika Westerberg)

 - speed up unplug and shutdown by assuming Thunderbolt controllers
   don't support Command Completed events (Lukas Wunner)

 - add AtomicOps support for GPU and Infiniband drivers (Felix Kuehling,
   Jay Cornwall)

 - expose "ari_enabled" in sysfs to help NIC naming (Stuart Hayes)

 - clean up PCI DMA interface usage (Christoph Hellwig)

 - remove PCI pool API (replaced with DMA pool) (Romain Perier)

 - deprecate pci_get_bus_and_slot(), which assumed PCI domain 0 (Sinan
   Kaya)

 - move DT PCI code from drivers/of/ to drivers/pci/ (Rob Herring)

 - add PCI-specific wrappers for dev_info(), etc (Frederick Lawler)

 - remove warnings on sysfs mmap failure (Bjorn Helgaas)

 - quiet ROM validation messages (Alex Deucher)

 - remove redundant memory alloc failure messages (Markus Elfring)

 - fill in types for compile-time VGA and other I/O port resources
   (Bjorn Helgaas)

 - make "pci=pcie_scan_all" work for Root Ports as well as Downstream
   Ports to help AmigaOne X1000 (Bjorn Helgaas)

 - add SPDX tags to all PCI files (Bjorn Helgaas)

 - quirk Marvell 9128 DMA aliases (Alex Williamson)

 - quirk broken INTx disable on Ceton InfiniTV4 (Bjorn Helgaas)

 - fix CONFIG_PCI=n build by adding dummy pci_irqd_intx_xlate() (Niklas
   Cassel)

 - use DMA API to get MSI address for DesignWare IP (Niklas Cassel)

 - fix endpoint-mode DMA mask configuration (Kishon Vijay Abraham I)

 - fix ARTPEC-6 incorrect IS_ERR() usage (Wei Yongjun)

 - add support for ARTPEC-7 SoC (Niklas Cassel)

 - add endpoint-mode support for ARTPEC (Niklas Cassel)

 - add Cadence PCIe host and endpoint controller driver (Cyrille
   Pitchen)

 - handle multiple INTx status bits being set in dra7xx (Vignesh R)

 - translate dra7xx hwirq range to fix INTD handling (Vignesh R)

 - remove deprecated Exynos PHY initialization code (Jaehoon Chung)

 - fix MSI erratum workaround for HiSilicon Hip06/Hip07 (Dongdong Liu)

 - fix NULL pointer dereference in iProc BCMA driver (Ray Jui)

 - fix Keystone interrupt-controller-node lookup (Johan Hovold)

 - constify qcom driver structures (Julia Lawall)

 - rework Tegra config space mapping to increase space available for
   endpoints (Vidya Sagar)

 - simplify Tegra driver by using bus->sysdata (Manikanta Maddireddy)

 - remove PCI_REASSIGN_ALL_BUS usage on Tegra (Manikanta Maddireddy)

 - add support for Global Fabric Manager Server (GFMS) event to
   Microsemi Switchtec switch driver (Logan Gunthorpe)

 - add IDs for Switchtec PSX 24xG3 and PSX 48xG3 (Kelvin Cao)

* tag 'pci-v4.16-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci: (140 commits)
  PCI: cadence: Add EndPoint Controller driver for Cadence PCIe controller
  dt-bindings: PCI: cadence: Add DT bindings for Cadence PCIe endpoint controller
  PCI: endpoint: Fix EPF device name to support multi-function devices
  PCI: endpoint: Add the function number as argument to EPC ops
  PCI: cadence: Add host driver for Cadence PCIe controller
  dt-bindings: PCI: cadence: Add DT bindings for Cadence PCIe host controller
  PCI: Add vendor ID for Cadence
  PCI: Add generic function to probe PCI host controllers
  PCI: generic: fix missing call of pci_free_resource_list()
  PCI: OF: Add generic function to parse and allocate PCI resources
  PCI: Regroup all PCI related entries into drivers/pci/Makefile
  PCI/DPC: Reformat DPC register definitions
  PCI/DPC: Add and use DPC Status register field definitions
  PCI/DPC: Squash dpc_rp_pio_get_info() into dpc_process_rp_pio_error()
  PCI/DPC: Remove unnecessary RP PIO register structs
  PCI/DPC: Push dpc->rp_pio_status assignment into dpc_rp_pio_get_info()
  PCI/DPC: Squash dpc_rp_pio_print_error() into dpc_rp_pio_get_info()
  PCI/DPC: Make RP PIO log size check more generic
  PCI/DPC: Rename local "status" to "dpc_status"
  PCI/DPC: Squash dpc_rp_pio_print_tlp_header() into dpc_rp_pio_print_error()
  ...

Pull alpha updates from Matt Turner:
 "A few small fixes and clean ups"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mattst88/alpha:
  alpha: fix crash if pthread_create races with signal delivery
  alpha: fix formating of stack content
  alpha: fix reboot on Avanti platform
  alpha: deprecate pci_get_bus_and_slot()
  alpha: Fix mixed up args in EXC macro in futex operations
  alpha: osf_sys.c: use timespec64 where appropriate
  alpha: osf_sys.c: fix put_tv32 regression
  alpha: make thread_saved_pc static
  alpha: make XTABS equivalent to TAB3

Pull clk updates from Stephen Boyd:
 "The core framework has a handful of patches this time around, mostly
  due to the clk rate protection support added by Jerome Brunet.

  This feature will allow consumers to lock in a certain rate on the
  output of a clk so that things like audio playback don't hear pops
  when the clk frequency changes due to shared parent clks changing
  rates. Currently the clk API doesn't guarantee the rate of a clk stays
  at the rate you request after clk_set_rate() is called, so this new
  API will allow drivers to express that requirement.

  Beyond this, the core got some debugfs pretty printing patches and a
  couple minor non-critical fixes.

  Looking outside of the core framework diff we have some new driver
  additions and the removal of a legacy TI clk driver. Both of these hit
  high in the dirstat. Also, the removal of the asm-generic/clkdev.h
  file causes small one-liners in all the architecture Kbuild files.

  Overall, the driver diff seems to be the normal stuff that comes all
  the time to fix little problems here and there and to support new
  hardware.

  Summary:

  Core:
   - Clk rate protection
   - Symbolic clk flags in debugfs output
   - Clk registration enabled clks while doing bookkeeping updates

  New Drivers:
   - Spreadtrum SC9860
   - HiSilicon hi3660 stub
   - Qualcomm A53 PLL, SPMI clkdiv, and MSM8916 APCS
   - Amlogic Meson-AXG
   - ASPEED BMC

  Removed Drivers:
   - TI OMAP 3xxx legacy clk (non-DT) support
   - asm*/clkdev.h got removed (not really a driver)

  Updates:
   - Renesas FDP1-0 module clock on R-Car M3-W
   - Renesas LVDS module clock on R-Car V3M
   - Misc fixes to pr_err() prints
   - Qualcomm MSM8916 audio fixes
   - Qualcomm IPQ8074 rounded out support for more peripherals
   - Qualcomm Alpha PLL variants
   - Divider code was using container_of() on bad pointers
   - Allwinner DE2 clks on H3
   - Amlogic minor data fixes and dropping of CLK_IGNORE_UNUSED
   - Mediatek clk driver compile test support
   - AT91 PMC clk suspend/resume restoration support
   - PLL issues fixed on si5351
   - Broadcom IProc PLL calculation updates
   - DVFS support for Armada mvebu CPU clks
   - Allwinner fixed post-divider support
   - TI clkctrl fixes and support for newer SoCs"

* tag 'clk-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux: (125 commits)
  clk: aspeed: Handle inverse polarity of USB port 1 clock gate
  clk: aspeed: Fix return value check in aspeed_cc_init()
  clk: aspeed: Add reset controller
  clk: aspeed: Register gated clocks
  clk: aspeed: Add platform driver and register PLLs
  clk: aspeed: Register core clocks
  clk: Add clock driver for ASPEED BMC SoCs
  clk: mediatek: adjust dependency of reset.c to avoid unexpectedly being built
  clk: fix reentrancy of clk_enable() on UP systems
  clk: meson-axg: fix potential NULL dereference in axg_clkc_probe()
  clk: Simplify debugfs registration
  clk: Fix debugfs_create_*() usage
  clk: Show symbolic clock flags in debugfs
  clk: renesas: r8a7796: Add FDP clock
  clk: Move __clk_{get,put}() into private clk.h API
  clk: sunxi: Use CLK_IS_CRITICAL flag for critical clks
  clk: Improve flags doc for of_clk_detect_critical()
  arch: Remove clkdev.h asm-generic from Kbuild
  clk: sunxi-ng: a83t: Add M divider to TCON1 clock
  clk: Prepare to remove asm-generic/clkdev.h
  ...

Pull asm/uaccess.h whack-a-mole from Al Viro:
 "It's linux/uaccess.h, damnit... Oh, well - eventually they'll stop
  cropping up..."

* 'work.whack-a-mole' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  asm-prototypes.h: use linux/uaccess.h, not asm/uaccess.h
  riscv: use linux/uaccess.h, not asm/uaccess.h...
  ppc: for put_user() pull linux/uaccess.h, not asm/uaccess.h

Pull dma mapping updates from Christoph Hellwig:
 "Except for a runtime warning fix from Christian this is all about
  consolidation of the generic no-IOMMU code, a well as the glue code
  for swiotlb.

  All the code is based on the x86 implementation with hooks to allow
  all architectures that aren't cache coherent to use it.

  The x86 conversion itself has been deferred because the x86
  maintainers were a little busy in the last months"

* tag 'dma-mapping-4.16' of git://git.infradead.org/users/hch/dma-mapping: (57 commits)
  MAINTAINERS: add the iommu list for swiotlb and xen-swiotlb
  arm64: use swiotlb_alloc and swiotlb_free
  arm64: replace ZONE_DMA with ZONE_DMA32
  mips: use swiotlb_{alloc,free}
  mips/netlogic: remove swiotlb support
  tile: use generic swiotlb_ops
  tile: replace ZONE_DMA with ZONE_DMA32
  unicore32: use generic swiotlb_ops
  ia64: remove an ifdef around the content of pci-dma.c
  ia64: clean up swiotlb support
  ia64: use generic swiotlb_ops
  ia64: replace ZONE_DMA with ZONE_DMA32
  swiotlb: remove various exports
  swiotlb: refactor coherent buffer allocation
  swiotlb: refactor coherent buffer freeing
  swiotlb: wire up ->dma_supported in swiotlb_dma_ops
  swiotlb: add common swiotlb_map_ops
  swiotlb: rename swiotlb_free to swiotlb_exit
  x86: rename swiotlb_dma_ops
  powerpc: rename swiotlb_dma_ops
  ...

Pull misc vfs updates from Al Viro:
 "All kinds of misc stuff, without any unifying topic, from various
  people.

  Neil's d_anon patch, several bugfixes, introduction of kvmalloc
  analogue of kmemdup_user(), extending bitfield.h to deal with
  fixed-endians, assorted cleanups all over the place..."

* 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (28 commits)
  alpha: osf_sys.c: use timespec64 where appropriate
  alpha: osf_sys.c: fix put_tv32 regression
  jffs2: Fix use-after-free bug in jffs2_iget()'s error handling path
  dcache: delete unused d_hash_mask
  dcache: subtract d_hash_shift from 32 in advance
  fs/buffer.c: fold init_buffer() into init_page_buffers()
  fs: fold __inode_permission() into inode_permission()
  fs: add RWF_APPEND
  sctp: use vmemdup_user() rather than badly open-coding memdup_user()
  snd_ctl_elem_init_enum_names(): switch to vmemdup_user()
  replace_user_tlv(): switch to vmemdup_user()
  new primitive: vmemdup_user()
  memdup_user(): switch to GFP_USER
  eventfd: fold eventfd_ctx_get() into eventfd_ctx_fileget()
  eventfd: fold eventfd_ctx_read() into eventfd_read()
  eventfd: convert to use anon_inode_getfd()
  nfs4file: get rid of pointless include of btrfs.h
  uvc_v4l2: clean copyin/copyout up
  vme_user: don't use __copy_..._user()
  usx2y: don't bother with memdup_user() for 16-byte structure
  ...

* pci/resource:
  PCI: tegra: Remove PCI_REASSIGN_ALL_BUS use on Tegra
  resource: Set type when reserving new regions
  resource: Set type of "reserve=" user-specified resources
  irqchip/i8259: Set I/O port resource types correctly
  powerpc: Set I/O port resource types correctly
  MIPS: Set I/O port resource types correctly
  vgacon: Set VGA struct resource types
  PCI: Use dev_info() rather than dev_err() for ROM validation
  PCI: Remove PCI_REASSIGN_ALL_RSRC use on arm and arm64
  PCI: Remove sysfs resource mmap warning

Conflicts:
	drivers/pci/rom.c