The return value should be non-zero under error conditions.
Remove nvme_free(dev) to avoid free dev more than once.
Signed-off-by: Wenwei Tao <ww.tao0320@gmail.com>
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>

The gendisk structure has not been initialized when using lightnvm.
Make sure to not delete it upon exit. Also make sure that we use the
appropriate disk_name at unregistration.
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>

The linear addressing mode was removed in 7386af27. Make null_blk instead
expose the ppa format geometry and support the generic addressing mode.
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>

Instead of using a page pool, we can save memory by only allocating room
for 64 entries for the ppa command. Introduce a ppa_cache to allocate only
the required memory for the ppa list.
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>

Reported-by: Paul Grabinar <paul.grabinar@ranbarg.com>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

Currently blk_insert_flush() just adds flush request to q->queue_head
when flush is not required. That completely bypasses IO scheduler so
e.g. CFQ can be idling waiting for new request to arrive and will idle
through the whole window unnecessarily. Luckily this only happens in
rare cases as usually checks in generic_make_request_checks() clear
FLUSH and FUA flags early if they are not needed.

When no flushing is actually required, we can easily fix the problem by
properly queueing the request through the IO scheduler. Ideally IO
scheduler should be also made aware of requests queued via
blk_flush_queue_rq(). However inserting flush request through IO
scheduler can have unwanted side-effects since due to flush batching
delaying the flush request in IO scheduler will delay all flush requests
possibly coming from other processes. So we keep adding the request
directly to q->queue_head.
Signed-off-by: Jan Kara <jack@suse.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

Add support for registering as a LightNVM device. This allows us to
evaluate the performance of the LightNVM subsystem.

In /drivers/Makefile, LightNVM is moved above block device drivers
to make sure that the LightNVM media managers have been initialized
before drivers under /drivers/block are initialized.
Signed-off-by: Matias Bjørling <m@bjorling.me>
Fix by Jens Axboe to remove unneeded slab cache and the following
memory leak.
Signed-off-by: Jens Axboe <axboe@fb.com>

To make the intention clearer, use list_{first,prev,next}_entry
instead of list_entry.
Signed-off-by: Geliang Tang <geliangtang@163.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

This prevents outstanding IOs to be sent for completion to target after
the target has been removed. The flow is now: stop new IOs > cleanup
queue > remove target.
Signed-off-by: Javier Gonzalez <javier@cnexlabs.com>
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>

The specification was updated the remove the double word just after
number of configuration groups and capabilities. Update the identify
structure to reflect it.
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>

The ppa format was not copied from the NVMe specific ppa format to the
lightnvm specific ppa format. This led to the ppa format not being
communicated to the layers above.
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>

The linear and device specific address modes can be replaced with a
simple offset and bit length conversion that is generic across all
devices.

This both simplifies the specification and removes the special case for
qemu nvme, that previously relied on the linear address mapping.
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>

Both the nvm_register and nvm_init does a kfree(dev) on error. Make sure
to only free it once.
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>

We register with nvm_devices when there registration can still fail.
Move the final registration at the end of the nvm_register function
to make sure we are fully registered when added to the nvm_devices list.
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>

Only NAND flash with SLC and MLC is supported. Make sure to not try to
initialize TLC memory or other non-volatile memory types.
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>

The nvm_id, nvm_id_group and nvm_addr_format data structures contain
reserved attributes. They are unused by media managers and targets.
Remove them.
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>

The mccap field is required for I/O command option support. It defines the
following flash access modes:

 * SLC mode
 * Erase/Program Suspension
 * Scramble On/Off
 * Encryption

It is slotted in between mpos and cpar, changing the offset for
cpar as well.
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>

A single 8 bit and 16 bit reserve field were inserted in the
specification to align fields appropriately. Reflect this in the
identify group structure.
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>

The specification was changed to reflect a multi-value bad block table.
Instead of bit-based bad block table, the bad block table now allows
eight bad block categories. Currently four are defined:

 * Factory bad blocks
 * Grown bad blocks
 * Device-side reserved blocks
 * Host-side reserved blocks

The factory and grown bad blocks are the regular bad blocks. The
reserved blocks are either for internal use or external use. In
particular, the device-side reserved blocks allows the host to
bootstrap from a limited number of flash blocks. Reducing the flash
blocks to scan upon super block initialization.

Support for both get bad block table and set bad block table is added.
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>

The max_phys_sect variable is defined as a char. We do a boundary check
to maximally allow 256 physical page descriptors per command. As we are
not indexing from zero. This expression is always false. Bump the
max_phys_sect to an unsigned int to support the range check.
Signed-off-by: Matias Bjørling <m@bjorling.me>
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Jens Axboe <axboe@fb.com>

Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>

Pull perf updates from Thomas Gleixner:
 "Mostly updates to the perf tool plus two fixes to the kernel core code:

   - Handle tracepoint filters correctly for inherited events (Peter
     Zijlstra)

   - Prevent a deadlock in perf_lock_task_context (Paul McKenney)

   - Add missing newlines to some pr_err() calls (Arnaldo Carvalho de
     Melo)

   - Print full source file paths when using 'perf annotate --print-line
     --full-paths' (Michael Petlan)

   - Fix 'perf probe -d' when just one out of uprobes and kprobes is
     enabled (Wang Nan)

   - Add compiler.h to list.h to fix 'make perf-tar-src-pkg' generated
     tarballs, i.e. out of tree building (Arnaldo Carvalho de Melo)

   - Add the llvm-src-base.c and llvm-src-kbuild.c files, generated by
     the 'perf test' LLVM entries, when running it in-tree, to
     .gitignore (Yunlong Song)

   - libbpf error reporting improvements, using a strerror interface to
     more precisely tell the user about problems with the provided
     scriptlet, be it in C or as a ready made object file (Wang Nan)

   - Do not be case sensitive when searching for matching 'perf test'
     entries (Arnaldo Carvalho de Melo)

   - Inform the user about objdump failures in 'perf annotate' (Andi
     Kleen)

   - Improve the LLVM 'perf test' entry, introduce a new ones for BPF
     and kbuild tests to check the environment used by clang to compile
     .c scriptlets (Wang Nan)"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (32 commits)
  perf/x86/intel/rapl: Remove the unused RAPL_EVENT_DESC() macro
  tools include: Add compiler.h to list.h
  perf probe: Verify parameters in two functions
  perf session: Add missing newlines to some pr_err() calls
  perf annotate: Support full source file paths for srcline fix
  perf test: Add llvm-src-base.c and llvm-src-kbuild.c to .gitignore
  perf: Fix inherited events vs. tracepoint filters
  perf: Disable IRQs across RCU RS CS that acquires scheduler lock
  perf test: Do not be case sensitive when searching for matching tests
  perf test: Add 'perf test BPF'
  perf test: Enhance the LLVM tests: add kbuild test
  perf test: Enhance the LLVM test: update basic BPF test program
  perf bpf: Improve BPF related error messages
  perf tools: Make fetch_kernel_version() publicly available
  bpf tools: Add new API bpf_object__get_kversion()
  bpf tools: Improve libbpf error reporting
  perf probe: Cleanup find_perf_probe_point_from_map to reduce redundancy
  perf annotate: Inform the user about objdump failures in --stdio
  perf stat: Make stat options global
  perf sched latency: Fix thread pid reuse issue
  ...

Pull scheduler fix from Thomas Gleixner:
 "A single fix to prevent math underflow in the numa balancing code"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/numa: Fix math underflow in task_tick_numa()

Pull liblockdep fixes from Thomas Gleixner:
 "Three small patches to synchronize liblockdep with the latest core
  changes"

* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  tools/liblockdep: explicitly declare lockdep API we call from liblockdep
  tools/liblockdep: add userspace versions of WRITE_ONCE and RCU_INIT_POINTER
  tools/liblockdep: remove task argument from debug_check_no_locks_held

Pull x86 fixes from Thomas Gleixner:
 "A couple of fixes and updates related to x86:

   - Fix the W+X check regression on XEN

   - The real fix for the low identity map trainwreck

   - Probe legacy PIC early instead of unconditionally allocating legacy
     irqs

   - Add cpu verification to long mode entry

   - Adjust the cache topology to AMD Fam17H systems

   - Let Merrifield use the TSC across S3"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/cpu: Call verify_cpu() after having entered long mode too
  x86/setup: Fix low identity map for >= 2GB kernel range
  x86/mm: Skip the hypervisor range when walking PGD
  x86/AMD: Fix last level cache topology for AMD Fam17h systems
  x86/irq: Probe for PIC presence before allocating descs for legacy IRQs
  x86/cpu/intel: Enable X86_FEATURE_NONSTOP_TSC_S3 for Merrifield

Merge branches 'irq-urgent-for-linus' and 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull irq and timer fixes from Thomas Gleixner:

 - An irq regression fix to restore the wakeup behaviour of chained
   interrupts.

 - A timer fix for a long standing race versus timers scheduled on a
   target cpu which got exposed by recent changes in the workqueue
   implementation.

* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  genirq/PM: Restore system wake up from chained interrupts

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  timers: Use proper base migration in add_timer_on()

Pull MIPS updates from Ralf Baechle:
 "These are the highlists of the main MIPS pull request for 4.4:

   - Add latencytop support
   - Support appended DTBs
   - VDSO support and initially use it for gettimeofday.
   - Drop the .MIPS.abiflags and ELF NOTE sections from vmlinux
   - Support for the 5KE, an internal test core.
   - Switch all MIPS platfroms to libata drivers.
   - Improved support, cleanups for ralink and Lantiq platforms.
   - Support for the new xilfpga platform.
   - A number of DTB improvments for BMIPS.
   - Improved support for CM and CPS.
   - Minor JZ4740 and BCM47xx enhancements"

* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus: (120 commits)
  MIPS: idle: add case for CPU_5KE
  MIPS: Octeon: Support APPENDED_DTB
  MIPS: vmlinux: create a section for appended DTB
  MIPS: Clean up compat_siginfo_t
  MIPS: Fix PAGE_MASK definition
  MIPS: BMIPS: Enable GZIP ramdisk and timed printks
  MIPS: Add xilfpga defconfig
  MIPS: xilfpga: Add mipsfpga platform code
  MIPS: xilfpga: Add xilfpga device tree files.
  dt-bindings: MIPS: Document xilfpga bindings and boot style
  MIPS: Make MIPS_CMDLINE_DTB default
  MIPS: Make the kernel arguments from dtb available
  MIPS: Use USE_OF as the guard for appended dtb
  MIPS: BCM63XX: Use pr_* instead of printk
  MIPS: Loongson: Cleanup CONFIG_LOONGSON_SUSPEND.
  MIPS: lantiq: Disable xbar fpi burst mode
  MIPS: lantiq: Force the crossbar to big endian
  MIPS: lantiq: Initialize the USB core on boot
  MIPS: lantiq: Return correct value for fpi clock on ar9
  MIPS: ralink: Add missing clock on rt305x
  ...

Pull sound fixes from Takashi Iwai:
 "Here are a collection of small fixes tha have been gathered for
  4.4-rc1.  The only significant changes are those in PCI drivers
  Kconfig, to use "depends on" instead of "select" for CONFIG_ZONE_DMA.
  A reverse select is often more user-friendly, but in this case, it
  makes hard to manage with the conflict with ZONE_DEVICE, so changed in
  such a way for now.

  Others are all small fixes and quirks: an error check in soundcore
  reigster_chrdev(), HD-audio HDMI/DP phantom jack fix, Intel Broxton DP
  quirk, USB-audio DSD device quirk, some constifications, etc"

* tag 'sound-fix-4.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound:
  ALSA: pci: depend on ZONE_DMA
  ALSA: hda - Simplify phantom jack handling for HDMI/DP
  ALSA: hda/hdmi - apply Skylake fix-ups to Broxton display codec
  ALSA: ctxfi: constify rsc ops structures
  ALSA: usb: Add native DSD support for Aune X1S
  ALSA: oxfw: add an comment to Kconfig for TASCAM FireOne
  sound: fix check for error condition of register_chrdev()

Pull ARC fixes from Vineet Gupta:
 "Found a couple of brown paper bag bugs with the prev pull request
  (including a SMP build breakage report from Guenter).  Since these are
  urgent I also decided to send over a bunch of other pending fixes
  which could have otherwise waited an rc or two.

  Summary:

   - A bunch of brown paper bag bugs (MAINTAINERS list email, SMP build
     failure)
   - cpu_relax() now compiler barrier for UP as well
   - handling of userspace Bus Errors for ARCompact builds"

* tag 'arc-4.4-rc1-part2' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc:
  ARC: Fix silly typo in MAINTAINERS file
  ARC: cpu_relax() to be compiler barrier even for UP
  ARC: use ASL assembler mnemonic
  ARC: [arcompact] Handle bus error from userspace as Interrupt not exception
  ARC: remove extraneous header include
  ARCv2: lib: memcpy: use local symbols

cpu_relax() on ARC has been barrier only for SMP (and no-op for UP). Per
recent discussions, it is safer to make it a compiler barrier
unconditionally.

Link: http://lkml.kernel.org/r/53A7D3AA.9020100@synopsys.comAcked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

ARCompact and ARCv2 only have ASL, while binutils used to support LSL as
a alias mnemonic.

Newer binutils (upstream) don't want to do that so replace it.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

Bus errors from userspace on ARCompact based cores are handled by core
as a high priority L2 interrupt but current code treated it as interrupt
Handling an interrupt like exception is certainly not going to go unnoticed.
(and it worked so far as we never saw a Bus error from userspace until
IPPK guys tested a DDR controller with ECC error detection etc hence
needed to explicitly trigger/handle such errors)

 - So move mem_service exception handler from common code into ARCv2 code.
 - In ARCompact code, define  mem_service as L2 interrupt handler which
   just drops down to pure kernel mode and goes of to enqueue SIGBUS
Reported-by: Nelson Pereira <npereira@synopsys.com>
Tested-by: Ana Martins <amartins@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

Merge tag 'chrome-platform-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/olof/chrome-platform

Pull chrome platform updates from Olof Johansson:
 "Here's the branch of chrome platform changes for v4.4.  Some have been
  queued up for the full 4.3 release cycle since I forgot to send them
  in for that round (rebased early on to deal with fixes conflicts).

  Most of these enable EC communication stuff -- Pixel 2015 support,
  enabling building for ARM64 platforms, and a few fixes for memory
  leaks.

  There's also a patch in here to allow reading/writing the verified
  boot context, which depends on a sysfs patch acked by Greg"

* tag 'chrome-platform-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/olof/chrome-platform:
  platform/chrome: Fix i2c-designware adapter name
  platform/chrome: Support reading/writing the vboot context
  sysfs: Support is_visible() on binary attributes
  platform/chrome: cros_ec: Fix possible leak in led_rgb_store()
  platform/chrome: cros_ec: Fix leak in sequence_store()
  platform/chrome: Enable Chrome platforms on 64-bit ARM
  platform/chrome: cros_ec_dev - Add a platform device ID table
  platform/chrome: cros_ec_lpc - Add support for Google Pixel 2
  platform/chrome: cros_ec_lpc - Use existing function to check EC result
  platform/chrome: Make depends on MFD_CROS_EC instead CROS_EC_PROTO
  Revert "platform/chrome: Don't make CHROME_PLATFORMS depends on X86 || ARM"

Merge tag 'platform-drivers-x86-v4.4-2' of git://git.infradead.org/users/dvhart/linux-platform-drivers-x86

Pull another x86 platform driver update from Darren Hart:
 "Support for the unfortunately rather unique ESC key on the Ideapad
  Yoga 3 and two DMI matches for rfkill support.  Solitary fix for
  potential missed errors for asus-wmi.  Downgrade a thinkpad_acpi
  message to info.

  asus-wmi:
   - fix error handling in store_sys_wmi()

  ideapad-laptop:
   - Add Lenovo Yoga 900 to no_hw_rfkill dmi list
   - include Yoga 3 1170 in add rfkill whitelist
   - add support for Yoga 3 ESC key

  thinkpad_acpi:
   - Don't yell on unsupported brightness interfaces"

* tag 'platform-drivers-x86-v4.4-2' of git://git.infradead.org/users/dvhart/linux-platform-drivers-x86:
  asus-wmi: fix error handling in store_sys_wmi()
  ideapad-laptop: Add Lenovo Yoga 900 to no_hw_rfkill dmi list
  ideapad-laptop: include Yoga 3 1170 in add rfkill whitelist
  ideapad-laptop: add support for Yoga 3 ESC key
  thinkpad_acpi: Don't yell on unsupported brightness interfaces

Pull more input updates from Dmitry Torokhov:
 "An update to the tsc2005 driver that allows it to also support tsc2004
  (basically the same controller, but uses i2c instead of spi bus), and
  a couple of bug fixes"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
  Input: parkbd - drop bogus __init from parkbd_allocate_serio()
  Input: elantech - add Fujitsu Lifebook U745 to force crc_enabled
  Input: tsc2004 - add support for tsc2004
  Input: tsc200x-core - rename functions and variables
  Input: tsc2005 - separate SPI and core functions

Pull final round of SCSI updates from James Bottomley:
 "Sorry for the delay in this patch which was mostly caused by getting
  the merger of the mpt2/mpt3sas driver, which was seen as an essential
  item of maintenance work to do before the drivers diverge too much.
  Unfortunately, this caused a compile failure (detected by linux-next),
  which then had to be fixed up and incubated.

  In addition to the mpt2/3sas rework, there are updates from pm80xx,
  lpfc, bnx2fc, hpsa, ipr, aacraid, megaraid_sas, storvsc and ufs plus
  an assortment of changes including some year 2038 issues, a fix for a
  remove before detach issue in some drivers and a couple of other minor
  issues"

* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (141 commits)
  mpt3sas: fix inline markers on non inline function declarations
  sd: Clear PS bit before Mode Select.
  ibmvscsi: set max_lun to 32
  ibmvscsi: display default value for max_id, max_lun and max_channel.
  mptfusion: don't allow negative bytes in kbuf_alloc_2_sgl()
  scsi: pmcraid: replace struct timeval with ktime_get_real_seconds()
  mvumi: 64bit value for seconds_since1970
  be2iscsi: Fix bogus WARN_ON length check
  scsi_scan: don't dump trace when scsi_prep_async_scan() is called twice
  mpt3sas: Bump mpt3sas driver version to 09.102.00.00
  mpt3sas: Single driver module which supports both SAS 2.0 & SAS 3.0 HBAs
  mpt2sas, mpt3sas: Update the driver versions
  mpt3sas: setpci reset kernel oops fix
  mpt3sas: Added OEM Gen2 PnP ID branding names
  mpt3sas: Refcount fw_events and fix unsafe list usage
  mpt3sas: Refcount sas_device objects and fix unsafe list usage
  mpt3sas: sysfs attribute to report Backup Rail Monitor Status
  mpt3sas: Ported WarpDrive product SSS6200 support
  mpt3sas: fix for driver fails EEH, recovery from injected pci bus error
  mpt3sas: Manage MSI-X vectors according to HBA device type
  ...

Pull SCSI target updates from Nicholas Bellinger:
 "This series contains HCH's changes to absorb configfs attribute
  ->show() + ->store() function pointer usage from it's original
  tree-wide consumers, into common configfs code.

  It includes usb-gadget, target w/ drivers, netconsole and ocfs2
  changes to realize the improved simplicity, that now renders the
  original include/target/configfs_macros.h CPP magic for fabric drivers
  and others, unnecessary and obsolete.

  And with common code in place, new configfs attributes can be added
  easier than ever before.

  Note, there are further improvements in-flight from other folks for
  v4.5 code in configfs land, plus number of target fixes for post -rc1
  code"

In the meantime, a new user of the now-removed old configfs API came in
through the char/misc tree in commit 7bd1d409 ("stm class: Introduce
an abstraction for System Trace Module devices").

This merge resolution comes from Alexander Shishkin, who updated his stm
class tracing abstraction to account for the removal of the old
show_attribute and store_attribute methods in commit 51798222
("configfs: remove old API") from this pull.  As Alexander says about
that patch:

 "There's no need to keep an extra wrapper structure per item and the
  awkward show_attribute/store_attribute item ops are no longer needed.

  This patch converts policy code to the new api, all the while making
  the code quite a bit smaller and easier on the eyes.

  Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>"

That patch was folded into the merge so that the tree should be fully
bisectable.

* 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending: (23 commits)
  configfs: remove old API
  ocfs2/cluster: use per-attribute show and store methods
  ocfs2/cluster: move locking into attribute store methods
  netconsole: use per-attribute show and store methods
  target: use per-attribute show and store methods
  spear13xx_pcie_gadget: use per-attribute show and store methods
  dlm: use per-attribute show and store methods
  usb-gadget/f_serial: use per-attribute show and store methods
  usb-gadget/f_phonet: use per-attribute show and store methods
  usb-gadget/f_obex: use per-attribute show and store methods
  usb-gadget/f_uac2: use per-attribute show and store methods
  usb-gadget/f_uac1: use per-attribute show and store methods
  usb-gadget/f_mass_storage: use per-attribute show and store methods
  usb-gadget/f_sourcesink: use per-attribute show and store methods
  usb-gadget/f_printer: use per-attribute show and store methods
  usb-gadget/f_midi: use per-attribute show and store methods
  usb-gadget/f_loopback: use per-attribute show and store methods
  usb-gadget/ether: use per-attribute show and store methods
  usb-gadget/f_acm: use per-attribute show and store methods
  usb-gadget/f_hid: use per-attribute show and store methods
  ...