This device has a broken vendor-specific altsetting for interface 1,
where endpoint 0x85 is declared as an isochronous endpoint despite being
used by interface 2 for audio capture.

Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass          239 Miscellaneous Device
  bDeviceSubClass         2
  bDeviceProtocol         1 Interface Association
  bMaxPacketSize0        64
  idVendor           0x0926
  idProduct          0x0202
  bcdDevice            1.00
  iManufacturer           1 Sound Devices
  iProduct                2 USBPre2
  iSerial                 3 [...]
  bNumConfigurations      1

[...]

    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       3
      bNumEndpoints           2
      bInterfaceClass       255 Vendor Specific Class
      bInterfaceSubClass      0
      bInterfaceProtocol      0
      iInterface              0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x85  EP 5 IN
        bmAttributes            5
          Transfer Type            Isochronous
          Synch Type               Asynchronous
          Usage Type               Data
        wMaxPacketSize     0x0126  1x 294 bytes
        bInterval               1

[...]

    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        2
      bAlternateSetting       1
      bNumEndpoints           1
      bInterfaceClass         1 Audio
      bInterfaceSubClass      2 Streaming
      bInterfaceProtocol      0
      iInterface              0
      AudioStreaming Interface Descriptor:
        bLength                 7
        bDescriptorType        36
        bDescriptorSubtype      1 (AS_GENERAL)
        bTerminalLink           4
        bDelay                  1 frames
        wFormatTag         0x0001 PCM
      AudioStreaming Interface Descriptor:
        bLength                26
        bDescriptorType        36
        bDescriptorSubtype      2 (FORMAT_TYPE)
        bFormatType             1 (FORMAT_TYPE_I)
        bNrChannels             2
        bSubframeSize           2
        bBitResolution         16
        bSamFreqType            6 Discrete
        tSamFreq[ 0]         8000
        tSamFreq[ 1]        16000
        tSamFreq[ 2]        24000
        tSamFreq[ 3]        32000
        tSamFreq[ 4]        44100
        tSamFreq[ 5]        48000
      Endpoint Descriptor:
        bLength                 9
        bDescriptorType         5
        bEndpointAddress     0x85  EP 5 IN
        bmAttributes            5
          Transfer Type            Isochronous
          Synch Type               Asynchronous
          Usage Type               Data
        wMaxPacketSize     0x0126  1x 294 bytes
        bInterval               4
        bRefresh                0
        bSynchAddress           0
        AudioStreaming Endpoint Descriptor:
          bLength                 7
          bDescriptorType        37
          bDescriptorSubtype      1 (EP_GENERAL)
          bmAttributes         0x01
            Sampling Frequency
          bLockDelayUnits         2 Decoded PCM samples
          wLockDelay         0x0000

Since commit 3e4f8e21 ("USB: core: fix check for duplicate
endpoints") USB core ignores any duplicate endpoints found during
descriptor parsing, but in this case we need to ignore the first
instance in order to avoid breaking the audio capture interface.

Fixes: 3e4f8e21 ("USB: core: fix check for duplicate endpoints")
Cc: stable <stable@vger.kernel.org>
Reported-by: edes <edes@gmx.net>
Tested-by: edes <edes@gmx.net>
Link: https://lore.kernel.org/r/20200201105829.5682c887@acme7.acmenetSigned-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20200203153830.26394-3-johan@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Add a new device quirk that can be used to blacklist endpoints.

Since commit 3e4f8e21 ("USB: core: fix check for duplicate
endpoints") USB core ignores any duplicate endpoints found during
descriptor parsing.

In order to handle devices where the first interfaces with duplicate
endpoints are the ones that should have their endpoints ignored, we need
to add a blacklist.
Tested-by: edes <edes@gmx.net>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20200203153830.26394-2-johan@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Currently the string formatting is mixing up the offset of ret and
len. Re-work the code to use just len, remove ret and use scnprintf
instead of snprintf and len position accumulation where required.
Remove the -ve return check since scnprintf never returns a failure
-ve size. Also break overly long lines to clean up checkpatch
warnings.

Addresses-Coverity: ("Unused value")
Fixes: 1381a511 ("usb: dwc3: debug: purge usage of strcat")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200210095139.328711-1-colin.king@canonical.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Tools like Coccinelle may erroneously recommend to use the
devm_platform_ioremap_resource() API for the registers mapping because
these tools are not aware about the implementation details of the driver.
Let's add a clarifying comments to the code, which should help to stop
future attempts to break the driver.
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Link: https://lore.kernel.org/r/20200202224259.29187-1-digetx@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Paul Zimmerman reports that his USB Bluetooth adapter sometimes
crashes following system resume, when it receives a
Get-Device-Descriptor request while it is busy doing something else.

Such a request was added by commit a4f55d8b ("usb: hub: Check
device descriptor before resusciation").  It gets sent when the hub
driver's work thread checks whether a connect-change event on an
enabled port really indicates a new device has been connected, as
opposed to an old device momentarily disconnecting and then
reconnecting (which can happen with xHCI host controllers, since they
automatically enable connected ports).

The same kind of thing occurs when a port's power session is lost
during system suspend.  When the system wakes up it sees a
connect-change event on the port, and if the child device's
persist_enabled flag was set then hub_activate() sets the device's
reset_resume flag as well as the port's bit in hub->change_bits.  The
reset-resume code then takes responsibility for checking that the same
device is still attached to the port, and it does this as part of the
device's resume pathway.  By the time the hub driver's work thread
starts up again, the device has already been fully reinitialized and
is busy doing its own thing.  There's no need for the work thread to
do the same check a second time, and in fact this unnecessary check is
what caused the problem that Paul observed.

Note that performing the unnecessary check is not actually a bug.
Devices are supposed to be able to send descriptors back to the host
even when they are busy doing something else.  The underlying cause of
Paul's problem lies in his Bluetooth adapter.  Nevertheless, we
shouldn't perform the same check twice in a row -- and as a nice side
benefit, removing the extra check allows the Bluetooth adapter to work
more reliably.

The work thread performs its check when it sees that the port's bit is
set in hub->change_bits.  In this situation that bit is interpreted as
though a connect-change event had occurred on the port _after_ the
reset-resume, which is not what actually happened.

One possible fix would be to make the reset-resume code clear the
port's bit in hub->change_bits.  But it seems simpler to just avoid
setting the bit during hub_activate() in the first place.  That's what
this patch does.

(Proving that the patch is correct when CONFIG_PM is disabled requires
a little thought.  In that setting hub_activate() will be called only
for initialization and resets, since there won't be any resumes or
reset-resumes.  During initialization and hub resets the hub doesn't
have any child devices, and so this code path never gets executed.)
Reported-and-tested-by: Paul Zimmerman <pauldzim@gmail.com>
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://marc.info/?t=157949360700001&r=1&w=2
CC: David Heinzelmann <heinzelmann.david@gmail.com>
CC: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/Pine.LNX.4.44L0.2001311037460.1577-100000@iolanthe.rowland.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

To work properly on every architectures and compilers, the enum value
needs to be specific numbers.
Suggested-by: Greg KH <gregkh@linuxfoundation.org>
Signed-off-by: Peter Chen <peter.chen@nxp.com>
Link: https://lore.kernel.org/r/1580537624-10179-1-git-send-email-peter.chen@nxp.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

When a uas disk is plugged into an external hub, uas_probe()
will be called by the hub thread to do the probe. It will
first create a SCSI host and then do the scan for this host.
During the scan, it will probe the LUN using SCSI INQUERY command
which will be packed in the URB and submitted to uas disk.

There might be a chance that this external hub with uas disk
attached is unplugged during the scan. In this case, uas driver
will fail to submit the URB (due to the NOTATTACHED state of uas
device) and try to put this SCSI command back to request queue
waiting for next chance to run.

In normal case, this cycle will terminate when hub thread gets
disconnection event and calls into uas_disconnect() accordingly.
But in this case, uas_disconnect() will not be called because
hub thread of external hub gets stuck waiting for the completion
of this SCSI command. A deadlock happened.

In this fix, uas will call scsi_scan_host() asynchronously to
avoid the blocking of hub thread.
Signed-off-by: EJ Hsu <ejh@nvidia.com>
Acked-by: Oliver Neukum <oneukum@suse.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200130092506.102760-1-ejh@nvidia.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Run parse-maintainers.pl and choose USB TYPEC records. Fix them accordingly.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20200128142956.39604-1-andriy.shevchenko@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Renesas R-Car H3ULCB + Kingfisher Infotainment Board is either not able
to detect the USB3.0 mass storage devices or is detecting those as
USB2.0 high speed devices.

The explanation given by Renesas is that, due to a HW issue, the XHCI
driver does not wake up after going to sleep on connecting a USB3.0
device.

In order to mitigate that, disable the auto-suspend feature
specifically for SMSC hubs from hub_probe() function, as a quirk.

Renesas Kingfisher Infotainment Board has two USB3.0 ports (CN2) which
are connected via USB5534B 4-port SuperSpeed/Hi-Speed, low-power,
configurable hub controller.

[1] SanDisk USB 3.0 device detected as USB-2.0 before the patch
 [   74.036390] usb 5-1.1: new high-speed USB device number 4 using xhci-hcd
 [   74.061598] usb 5-1.1: New USB device found, idVendor=0781, idProduct=5581, bcdDevice= 1.00
 [   74.069976] usb 5-1.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
 [   74.077303] usb 5-1.1: Product: Ultra
 [   74.080980] usb 5-1.1: Manufacturer: SanDisk
 [   74.085263] usb 5-1.1: SerialNumber: 4C530001110208116550

[2] SanDisk USB 3.0 device detected as USB-3.0 after the patch
 [   34.565078] usb 6-1.1: new SuperSpeed Gen 1 USB device number 3 using xhci-hcd
 [   34.588719] usb 6-1.1: New USB device found, idVendor=0781, idProduct=5581, bcdDevice= 1.00
 [   34.597098] usb 6-1.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
 [   34.604430] usb 6-1.1: Product: Ultra
 [   34.608110] usb 6-1.1: Manufacturer: SanDisk
 [   34.612397] usb 6-1.1: SerialNumber: 4C530001110208116550
Suggested-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Hardik Gajjar <hgajjar@de.adit-jv.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Tested-by: Eugeniu Rosca <erosca@de.adit-jv.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/1580989763-32291-1-git-send-email-hgajjar@de.adit-jv.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Intel Comet Lake based platform require the XHCI_PME_STUCK_QUIRK
quirk as well. Without this xHC can not enter D3 in runtime suspend.

Cc: stable@vger.kernel.org
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20200210134553.9144-5-mathias.nyman@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Intel hosts that need the XHCI_PME_STUCK_QUIRK flag should enable
runtime pm by calling xhci_pme_acpi_rtd3_enable() before
usb_hcd_pci_probe() calls pci_dev_run_wake().
Otherwise usage count for the device won't be decreased, and runtime
suspend is prevented.

usb_hcd_pci_probe() only decreases the usage count if device can
generate run-time wake-up events, i.e. when pci_dev_run_wake()
returns true.

This issue was exposed by pci_dev_run_wake() change in
commit 8feaec33 ("PCI / PM: Always check PME wakeup capability for
runtime wakeup support")
and should be backported to kernels with that change

Cc: <stable@vger.kernel.org> # 4.13+
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20200210134553.9144-4-mathias.nyman@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

xhci driver assumed that xHC controllers have at most one custom
supported speed table (PSI) for all usb 3.x ports.
Memory was allocated for one PSI table under the xhci hub structure.

Turns out this is not the case, some controllers have a separate
"supported protocol capability" entry with a PSI table for each port.
This means each usb3 roothub port can in theory support different custom
speeds.

To solve this, cache all supported protocol capabilities with their PSI
tables in an array, and add pointers to the xhci port structure so that
every port points to its capability entry in the array.

When creating the SuperSpeedPlus USB Device Capability BOS descriptor
for the xhci USB 3.1 roothub we for now will use only data from the
first USB 3.1 capable protocol capability entry in the array.
This could be improved later, this patch focuses resolving
the memory leak.
Reported-by: Paul Menzel <pmenzel@molgen.mpg.de>
Reported-by: Sajja Venkateswara Rao <VenkateswaraRao.Sajja@amd.com>
Fixes: 47189098 ("xhci: parse xhci protocol speed ID list for usb 3.1 usage")
Cc: stable <stable@vger.kernel.org> # v4.4+
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20200210134553.9144-3-mathias.nyman@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

A Full-speed bulk USB audio device (DJ-Tech CTRL) with a invalid Maximum
Packet Size of 4 causes a xHC "Parameter Error" at enumeration.

This is because valid Maximum packet sizes for Full-speed bulk endpoints
are 8, 16, 32 and 64 bytes. Hosts are not required to support other values
than these. See usb 2 specs section 5.8.3 for details.

The device starts working after forcing the maximum packet size to 8.
This is most likely the case with other devices as well, so force the
maximum packet size to a valid range.

Cc: stable@vger.kernel.org
Reported-by: Rene D Obermueller <cmdrrdo@gmail.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20200210134553.9144-2-mathias.nyman@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Pull more Kbuild updates from Masahiro Yamada:

 - fix randconfig to generate a sane .config

 - rename hostprogs-y / always to hostprogs / always-y, which are more
   natual syntax.

 - optimize scripts/kallsyms

 - fix yes2modconfig and mod2yesconfig

 - make multiple directory targets ('make foo/ bar/') work

* tag 'kbuild-v5.6-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  kbuild: make multiple directory targets work
  kconfig: Invalidate all symbols after changing to y or m.
  kallsyms: fix type of kallsyms_token_table[]
  scripts/kallsyms: change table to store (strcut sym_entry *)
  scripts/kallsyms: rename local variables in read_symbol()
  kbuild: rename hostprogs-y/always to hostprogs/always-y
  kbuild: fix the document to use extra-y for vmlinux.lds
  kconfig: fix broken dependency in randconfig-generated .config

Pull new zonefs file system from Damien Le Moal:
 "Zonefs is a very simple file system exposing each zone of a zoned
  block device as a file.

  Unlike a regular file system with native zoned block device support
  (e.g. f2fs or the on-going btrfs effort), zonefs does not hide the
  sequential write constraint of zoned block devices to the user. As a
  result, zonefs is not a POSIX compliant file system. Its goal is to
  simplify the implementation of zoned block devices support in
  applications by replacing raw block device file accesses with a richer
  file based API, avoiding relying on direct block device file ioctls
  which may be more obscure to developers.

  One example of this approach is the implementation of LSM
  (log-structured merge) tree structures (such as used in RocksDB and
  LevelDB) on zoned block devices by allowing SSTables to be stored in a
  zone file similarly to a regular file system rather than as a range of
  sectors of a zoned device. The introduction of the higher level
  construct "one file is one zone" can help reducing the amount of
  changes needed in the application while at the same time allowing the
  use of zoned block devices with various programming languages other
  than C.

  Zonefs IO management implementation uses the new iomap generic code.
  Zonefs has been successfully tested using a functional test suite
  (available with zonefs userland format tool on github) and a prototype
  implementation of LevelDB on top of zonefs"

* tag 'zonefs-5.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/dlemoal/zonefs:
  zonefs: Add documentation
  fs: New zonefs file system

In order to allow the GICv4 code to link properly on 32bit ARM,
make sure we don't use 64bit divisions when it isn't strictly
necessary.

Fixes: 4e6437f1 ("irqchip/gic-v4.1: Ensure L2 vPE table is allocated at RD level")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull cifs fixes from Steve French:
 "13 cifs/smb3 patches, most from testing at the SMB3 plugfest this week:

   - Important fix for multichannel and for modefromsid mounts.

   - Two reconnect fixes

   - Addition of SMB3 change notify support

   - Backup tools fix

   - A few additional minor debug improvements (tracepoints and
     additional logging found useful during testing this week)"

* tag '5.6-rc-smb3-plugfest-patches' of git://git.samba.org/sfrench/cifs-2.6:
  smb3: Add defines for new information level, FileIdInformation
  smb3: print warning once if posix context returned on open
  smb3: add one more dynamic tracepoint missing from strict fsync path
  cifs: fix mode bits from dir listing when mounted with modefromsid
  cifs: fix channel signing
  cifs: add SMB3 change notification support
  cifs: make multichannel warning more visible
  cifs: fix soft mounts hanging in the reconnect code
  cifs: Add tracepoints for errors on flush or fsync
  cifs: log warning message (once) if out of disk space
  cifs: fail i/o on soft mounts if sessionsetup errors out
  smb3: fix problem with null cifs super block with previous patch
  SMB3: Backup intent flag missing from some more ops

Pull vboxfs from Al Viro:
 "This is the VirtualBox guest shared folder support by Hans de Goede,
  with fixups for fs_parse folded in to avoid bisection hazards from
  those API changes..."

* 'work.vboxsf' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  fs: Add VirtualBox guest shared folder (vboxsf) support

Pull x86 fixes from Thomas Gleixner:
 "A set of fixes for X86:

   - Ensure that the PIT is set up when the local APIC is disable or
     configured in legacy mode. This is caused by an ordering issue
     introduced in the recent changes which skip PIT initialization when
     the TSC and APIC frequencies are already known.

   - Handle malformed SRAT tables during early ACPI parsing which caused
     an infinite loop anda boot hang.

   - Fix a long standing race in the affinity setting code which affects
     PCI devices with non-maskable MSI interrupts. The problem is caused
     by the non-atomic writes of the MSI address (destination APIC id)
     and data (vector) fields which the device uses to construct the MSI
     message. The non-atomic writes are mandated by PCI.

     If both fields change and the device raises an interrupt after
     writing address and before writing data, then the MSI block
     constructs a inconsistent message which causes interrupts to be
     lost and subsequent malfunction of the device.

     The fix is to redirect the interrupt to the new vector on the
     current CPU first and then switch it over to the new target CPU.
     This allows to observe an eventually raised interrupt in the
     transitional stage (old CPU, new vector) to be observed in the APIC
     IRR and retriggered on the new target CPU and the new vector.

     The potential spurious interrupts caused by this are harmless and
     can in the worst case expose a buggy driver (all handlers have to
     be able to deal with spurious interrupts as they can and do happen
     for various reasons).

   - Add the missing suspend/resume mechanism for the HYPERV hypercall
     page which prevents resume hibernation on HYPERV guests. This
     change got lost before the merge window.

   - Mask the IOAPIC before disabling the local APIC to prevent
     potentially stale IOAPIC remote IRR bits which cause stale
     interrupt lines after resume"

* tag 'x86-urgent-2020-02-09' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/apic: Mask IOAPIC entries when disabling the local APIC
  x86/hyperv: Suspend/resume the hypercall page for hibernation
  x86/apic/msi: Plug non-maskable MSI affinity race
  x86/boot: Handle malformed SRAT tables during early ACPI parsing
  x86/timer: Don't skip PIT setup when APIC is disabled or in legacy mode

Pull SMP fixes from Thomas Gleixner:
 "Two fixes for the SMP related functionality:

   - Make the UP version of smp_call_function_single() match SMP
     semantics when called for a not available CPU. Instead of emitting
     a warning and assuming that the function call target is CPU0,
     return a proper error code like the SMP version does.

   - Remove a superfluous check in smp_call_function_many_cond()"

* tag 'smp-urgent-2020-02-09' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  smp/up: Make smp_call_function_single() match SMP semantics
  smp: Remove superfluous cond_func check in smp_call_function_many_cond()

Pull perf fixes from Thomas Gleixner:
 "A set of fixes and improvements for the perf subsystem:

  Kernel fixes:

   - Install cgroup events to the correct CPU context to prevent a
     potential list double add

   - Prevent an integer underflow in the perf mlock accounting

   - Add a missing prototype for arch_perf_update_userpage()

  Tooling:

   - Add a missing unlock in the error path of maps__insert() in perf
     maps.

   - Fix the build with the latest libbfd

   - Fix the perf parser so it does not delete parse event terms, which
     caused a regression for using perf with the ARM CoreSight as the
     sink configuration was missing due to the deletion.

   - Fix the double free in the perf CPU map merging test case

   - Add the missing ustring support for the perf probe command"

* tag 'perf-urgent-2020-02-09' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf maps: Add missing unlock to maps__insert() error case
  perf probe: Add ustring support for perf probe command
  perf: Make perf able to build with latest libbfd
  perf test: Fix test case Merge cpu map
  perf parse: Copy string to perf_evsel_config_term
  perf parse: Refactor 'struct perf_evsel_config_term'
  kernel/events: Add a missing prototype for arch_perf_update_userpage()
  perf/cgroups: Install cgroup events to correct cpuctx
  perf/core: Fix mlock accounting in perf_mmap()

Pull timer fixes from Thomas Gleixner:
 "Two small fixes for the time(r) subsystem:

   - Handle a subtle race between the clocksource watchdog and a
     concurrent clocksource watchdog stop/start sequence correctly to
     prevent a timer double add bug.

   - Fix the file path for the core time namespace file"

* tag 'timers-urgent-2020-02-09' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  clocksource: Prevent double add_timer_on() for watchdog_timer
  MAINTAINERS: Correct path to time namespace source file

Pull interrupt fixes from Thomas Gleixner:
 "A set of fixes for the interrupt subsystem:

   - Provision only ACPI enabled redistributors on GICv3

   - Use the proper command colums when building the INVALL command for
     the GICv3-ITS

   - Ensure the allocation of the L2 vPE table for GICv4.1

   - Correct the GICv4.1 VPROBASER programming so it uses the proper
     size

   - A set of small GICv4.1 tidy up patches

   - Configuration cleanup for C-SKY interrupt chip

   - Clarify the function documentation for irq_set_wake() to document
     that the wakeup functionality is orthogonal to the irq
     disable/enable mechanism"

* tag 'irq-urgent-2020-02-09' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irqchip/gic-v3-its: Rename VPENDBASER/VPROPBASER accessors
  irqchip/gic-v3-its: Remove superfluous WARN_ON
  irqchip/gic-v4.1: Drop 'tmp' in inherit_vpe_l1_table_from_rd()
  irqchip/gic-v4.1: Ensure L2 vPE table is allocated at RD level
  irqchip/gic-v4.1: Set vpe_l1_base for all redistributors
  irqchip/gic-v4.1: Fix programming of GICR_VPROPBASER_4_1_SIZE
  genirq: Clarify that irq wake state is orthogonal to enable/disable
  irqchip/gic-v3-its: Reference to its_invall_cmd descriptor when building INVALL
  irqchip: Some Kconfig cleanup for C-SKY
  irqchip/gic-v3: Only provision redistributors that are enabled in ACPI

Pull EFI fix from Thomas Gleixner:
 "A single fix for a EFI boot regression on X86 which was caused by the
  recent rework of the EFI memory map parsing. On systems with invalid
  memmap entries the cleanup function uses an value which cannot be
  relied on in this stage. Use the actual EFI memmap entry instead"

* tag 'efi-urgent-2020-02-09' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  efi/x86: Fix boot regression on systems with invalid memmap entries

Pull misc SCSI fixes from James Bottomley:
 "Five small patches, all in drivers or doc, which missed the initial
  pull request.

  The qla2xxx and megaraid_sas are actual fixes and the rest are
  spelling and doc changes"

* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: ufs: fix spelling mistake "initilized" -> "initialized"
  scsi: pm80xx: fix spelling mistake "to" -> "too"
  scsi: MAINTAINERS: ufs: remove pedrom.sousa@synopsys.com
  scsi: megaraid_sas: fixup MSIx interrupt setup during resume
  scsi: qla2xxx: Fix unbound NVME response length

Pull networking fixes from David Miller:

 1) Unbalanced locking in mwifiex_process_country_ie, from Brian Norris.

 2) Fix thermal zone registration in iwlwifi, from Andrei
    Otcheretianski.

 3) Fix double free_irq in sgi ioc3 eth, from Thomas Bogendoerfer.

 4) Use after free in mptcp, from Florian Westphal.

 5) Use after free in wireguard's root_remove_peer_lists, from Eric
    Dumazet.

 6) Properly access packets heads in bonding alb code, from Eric
    Dumazet.

 7) Fix data race in skb_queue_len(), from Qian Cai.

 8) Fix regression in r8169 on some chips, from Heiner Kallweit.

 9) Fix XDP program ref counting in hv_netvsc, from Haiyang Zhang.

10) Certain kinds of set link netlink operations can cause a NULL deref
    in the ipv6 addrconf code. Fix from Eric Dumazet.

11) Don't cancel uninitialized work queue in drop monitor, from Ido
    Schimmel.

* git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (84 commits)
  net: thunderx: use proper interface type for RGMII
  mt76: mt7615: fix max_nss in mt7615_eeprom_parse_hw_cap
  bpf: Improve bucket_log calculation logic
  selftests/bpf: Test freeing sockmap/sockhash with a socket in it
  bpf, sockhash: Synchronize_rcu before free'ing map
  bpf, sockmap: Don't sleep while holding RCU lock on tear-down
  bpftool: Don't crash on missing xlated program instructions
  bpf, sockmap: Check update requirements after locking
  drop_monitor: Do not cancel uninitialized work item
  mlxsw: spectrum_dpipe: Add missing error path
  mlxsw: core: Add validation of hardware device types for MGPIR register
  mlxsw: spectrum_router: Clear offload indication from IPv6 nexthops on abort
  selftests: mlxsw: Add test cases for local table route replacement
  mlxsw: spectrum_router: Prevent incorrect replacement of local table routes
  net: dsa: microchip: enable module autoprobe
  ipv6/addrconf: fix potential NULL deref in inet6_set_link_af()
  dpaa_eth: support all modes with rate adapting PHYs
  net: stmmac: update pci platform data to use phy_interface
  net: stmmac: xgmac: fix missing IFF_MULTICAST checki in dwxgmac2_set_filter
  net: stmmac: fix missing IFF_MULTICAST check in dwmac4_set_filter
  ...

VirtualBox hosts can share folders with guests, this commit adds a
VFS driver implementing the Linux-guest side of this, allowing folders
exported by the host to be mounted under Linux.

This driver depends on the guest <-> host IPC functions exported by
the vboxguest driver.
Acked-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Pull powerpc fixes from Michael Ellerman:

 - Fix an existing bug in our user access handling, exposed by one of
   the bug fixes we merged this cycle.

 - A fix for a boot hang on 32-bit with CONFIG_TRACE_IRQFLAGS and the
   recently added CONFIG_VMAP_STACK.

Thanks to: Christophe Leroy, Guenter Roeck.

* tag 'powerpc-5.6-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc: Fix CONFIG_TRACE_IRQFLAGS with CONFIG_VMAP_STACK
  powerpc/futex: Fix incorrect user access blocking

This is a merge error on my part - the driver was merged into mainline
by commit c5951e7c ("Merge tag 'mips_5.6' of git://../mips/linux")
over a week ago, but nobody apparently noticed that it didn't actually
build due to still having a reference to the devm_ioremap_nocache()
function, removed a few days earlier through commit 6a1000bd ("Merge
tag 'ioremap-5.6' of git://../ioremap").

Apparently this didn't get any build testing anywhere.  Not perhaps all
that surprising: it's restricted to 64-bit MIPS only, and only with the
new SGI_MFD_IOC3 support enabled.

I only noticed because the ioremap conflicts in the ARM SoC driver
update made me check there weren't any others hiding, and I found this
one.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull ARM SoC late updates from Olof Johansson:
 "This is some material that we picked up into our tree late, or that
  had more complex dependencies on more than one topic branch that makes
  sense to keep separately.

   - TI support for secure accelerators and hwrng on OMAP4/5

   - TI camera changes for dra7 and am437x and SGX improvement due to
     better reset control support on am335x, am437x and dra7

   - Davinci moves to proper clocksource on DM365, and regulator/audio
     improvements for DM365 and DM644x eval boards"

* tag 'armsoc-late' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc: (32 commits)
  ARM: dts: omap4-droid4: Enable hdq for droid4 ds250x 1-wire battery nvmem
  ARM: dts: motorola-cpcap-mapphone: Configure calibration interrupt
  ARM: dts: Configure interconnect target module for am437x sgx
  ARM: dts: Configure sgx for dra7
  ARM: dts: Configure rstctrl reset for am335x SGX
  ARM: dts: dra7: Add ti-sysc node for VPE
  ARM: dts: dra7: add vpe clkctrl node
  ARM: dts: am43x-epos-evm: Add VPFE and OV2659 entries
  ARM: dts: am437x-sk-evm: Add VPFE and OV2659 entries
  ARM: dts: am43xx: add support for clkout1 clock
  arm: dts: dra76-evm: Add CAL and OV5640 nodes
  arm: dtsi: dra76x: Add CAL dtsi node
  arm: dts: dra72-evm-common: Add entries for the CSI2 cameras
  ARM: dts: DRA72: Add CAL dtsi node
  ARM: dts: dra7-l4: Add ti-sysc node for CAM
  ARM: OMAP: DRA7xx: Make CAM clock domain SWSUP only
  ARM: dts: dra7: add cam clkctrl node
  ARM: OMAP2+: Drop legacy platform data for omap4 des
  ARM: OMAP2+: Drop legacy platform data for omap4 sham
  ARM: OMAP2+: Drop legacy platform data for omap4 aes
  ...

Pull ARM SoC defconfig updates from Olof Johansson:
 "We keep this in a separate branch to avoid cross-branch conflicts, but
  most of the material here is fairly boring -- some new drivers turned
  on for hardware since they were merged, and some refreshed files due
  to time having moved a lot of entries around"

* tag 'armsoc-defconfig' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc: (38 commits)
  ARM: configs: at91: enable MMC_SDHCI_OF_AT91 and MICROCHIP_PIT64B
  arm64: defconfig: Enable Broadcom's GENET Ethernet controller
  ARM: multi_v7_defconfig: Enable devfreq thermal integration
  ARM: exynos_defconfig: Enable devfreq thermal integration
  ARM: multi_v7_defconfig: Enable NFS v4.1 and v4.2
  ARM: exynos_defconfig: Enable NFS v4.1 and v4.2
  arm64: defconfig: Enable Actions Semi specific drivers
  arm64: defconfig: Enable Broadcom's STB PCIe controller
  arm64: defconfig: Enable CONFIG_CLK_IMX8MP by default
  ARM: configs: at91: enable config flags for sam9x60 SoC
  ARM: configs: at91: use savedefconfig
  arm64: defconfig: Enable tegra XUDC support
  ARM: defconfig: gemini: Update defconfig
  arm64: defconfig: enable CONFIG_ARM_QCOM_CPUFREQ_NVMEM
  arm64: defconfig: enable CONFIG_QCOM_CPR
  arm64: defconfig: Enable HFPLL
  arm64: defconfig: Enable CRYPTO_DEV_FSL_CAAM
  ARM: imx_v6_v7_defconfig: Select the TFP410 driver
  ARM: imx_v6_v7_defconfig: Enable NFS_V4_1 and NFS_V4_2 support
  arm64: defconfig: Enable ATH10K_SNOC
  ...

Pull ARM SoC-related driver updates from Olof Johansson:
 "Various driver updates for platforms:

   - Nvidia: Fuse support for Tegra194, continued memory controller
     pieces for Tegra30

   - NXP/FSL: Refactorings of QuickEngine drivers to support
     ARM/ARM64/PPC

   - NXP/FSL: i.MX8MP SoC driver pieces

   - TI Keystone: ring accelerator driver

   - Qualcomm: SCM driver cleanup/refactoring + support for new SoCs.

   - Xilinx ZynqMP: feature checking interface for firmware. Mailbox
     communication for power management

   - Overall support patch set for cpuidle on more complex hierarchies
     (PSCI-based)

  and misc cleanups, refactorings of Marvell, TI, other platforms"

* tag 'armsoc-drivers' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc: (166 commits)
  drivers: soc: xilinx: Use mailbox IPI callback
  dt-bindings: power: reset: xilinx: Add bindings for ipi mailbox
  drivers: soc: ti: knav_qmss_queue: Pass lockdep expression to RCU lists
  MAINTAINERS: Add brcmstb PCIe controller entry
  soc/tegra: fuse: Unmap registers once they are not needed anymore
  soc/tegra: fuse: Correct straps' address for older Tegra124 device trees
  soc/tegra: fuse: Warn if straps are not ready
  soc/tegra: fuse: Cache values of straps and Chip ID registers
  memory: tegra30-emc: Correct error message for timed out auto calibration
  memory: tegra30-emc: Firm up hardware programming sequence
  memory: tegra30-emc: Firm up suspend/resume sequence
  soc/tegra: regulators: Do nothing if voltage is unchanged
  memory: tegra: Correct reset value of xusb_hostr
  soc/tegra: fuse: Add APB DMA dependency for Tegra20
  bus: tegra-aconnect: Remove PM_CLK dependency
  dt-bindings: mediatek: add MT6765 power dt-bindings
  soc: mediatek: cmdq: delete not used define
  memory: tegra: Add support for the Tegra194 memory controller
  memory: tegra: Only include support for enabled SoCs
  memory: tegra: Support DVFS on Tegra186 and later
  ...

Pull ARM Device-tree updates from Olof Johansson:
 "New SoCs:

   - Atmel/Microchip SAM9X60 (ARM926 SoC)

   - OMAP 37xx gets split into AM3703/AM3715/DM3725, who are all
     variants of it with different GPU/media IP configurations.

   - ST stm32mp15 SoCs (1-2 Cortex-A7, CAN, GPU depending on SKU)

   - ST Ericsson ab8505 (variant of ab8500) and db8520 (variant of
     db8500)

   - Unisoc SC9863A SoC (8x Cortex-A55 mobile chipset w/ GPU, modem)

   - Qualcomm SC7180 (8-core 64bit SoC, unnamed CPU class)

  New boards:

   - Allwinner:
      + Emlid Neutis SoM (H3 variant)
      + Libre Computer ALL-H3-IT
      + PineH64 Model B

   - Amlogic:
      + Libretech Amlogic GX PC (s905d and s912-based variants)

   - Atmel/Microchip:
      + Kizboxmini, sam9x60 EK, sama5d27 Wireless SOM (wlsom1)

   - Marvell:
      + Armada 385-based SolidRun Clearfog GTR

   - NXP:
      + Gateworks GW59xx boards based on i.MX6/6Q/6QDL
      + Tolino Shine 3 eBook reader (i.MX6sl)
      + Embedded Artists COM (i.MX7ULP)
      + SolidRun CLearfog CX/ITX and HoneyComb (LX2160A-based systems)
      + Google Coral Edge TPU (i.MX8MQ)

   - Rockchip:
      + Radxa Dalang Carrier (supports rk3288 and rk3399 SOMs)
      + Radxa Rock Pi N10 (RK3399Pro-based)
      + VMARC RK3399Pro SOM

   - ST:
      + Reference boards for stm32mp15

   - ST Ericsson:
      + Samsung Galaxy S III mini (GT-I8190)
      + HREF520 reference board for DB8520

   - TI OMAP:
      + Gen1 Amazon Echo (OMAP3630-based)

   - Qualcomm:
      + Inforce 6640 Single Board Computer (msm8996-based)
      + SC7180 IDP (SC7180-based)"

* tag 'armsoc-dt' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc: (623 commits)
  dt-bindings: fix compilation error of the example in marvell,mmp3-hsic-phy.yaml
  arm64: dts: ti: k3-am654-base-board: Add CSI2 OV5640 camera
  arm64: dts: ti: k3-am65-main Add CAL node
  arm64: dts: ti: k3-j721e-main: Add McASP nodes
  arm64: dts: ti: k3-am654-main: Add McASP nodes
  arm64: dts: ti: k3-j721e: DMA support
  arm64: dts: ti: k3-j721e-main: Move secure proxy and smmu under main_navss
  arm64: dts: ti: k3-j721e-main: Correct main NAVSS representation
  arm64: dts: ti: k3-j721e: Correct the address for MAIN NAVSS
  arm64: dts: ti: k3-am65: DMA support
  arm64: dts: ti: k3-am65-main: Move secure proxy under cbass_main_navss
  arm64: dts: ti: k3-am65-main: Correct main NAVSS representation
  ARM: dts: aspeed: rainier: Add UCD90320 power sequencer
  ARM: dts: aspeed: rainier: Switch PSUs to unknown version
  arm64: dts: rockchip: Kill off "simple-panel" compatibles
  ARM: dts: rockchip: Kill off "simple-panel" compatibles
  arm64: dts: rockchip: rename dwmmc node names to mmc
  ARM: dts: rockchip: rename dwmmc node names to mmc
  arm64: dts: exynos: Rename Samsung and Exynos to lowercase
  arm64: dts: uniphier: add reset-names to NAND controller node
  ...

Pull ARM SoC platform updates from Olof Johansson:
 "Most of these are smaller fixes that have accrued, and some continued
  cleanup of OMAP platforms towards shared frameworks.

  One new SoC from Atmel/Microchip: sam9x60"

* tag 'armsoc-soc' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc: (35 commits)
  ARM: OMAP2+: Fix undefined reference to omap_secure_init
  ARM: s3c64xx: Drop unneeded select of TIMER_OF
  ARM: exynos: Drop unneeded select of MIGHT_HAVE_CACHE_L2X0
  ARM: s3c24xx: Switch to atomic pwm API in rx1950
  ARM: OMAP2+: sleep43xx: Call secure suspend/resume handlers
  ARM: OMAP2+: Use ARM SMC Calling Convention when OP-TEE is available
  ARM: OMAP2+: Introduce check for OP-TEE in omap_secure_init()
  ARM: OMAP2+: Add omap_secure_init callback hook for secure initialization
  ARM: at91: Documentation: add sam9x60 product and datasheet
  ARM: at91: pm: use of_device_id array to find the proper shdwc node
  ARM: at91: pm: use SAM9X60 PMC's compatible
  ARM: imx: only select ARM_ERRATA_814220 for ARMv7-A
  ARM: zynq: use physical cpuid in zynq_slcr_cpu_stop/start
  ARM: tegra: Use clk_m CPU on Tegra124 LP1 resume
  ARM: tegra: Modify reshift divider during LP1
  ARM: tegra: Enable PLLP bypass during Tegra124 LP1
  ARM: samsung: Rename Samsung and Exynos to lowercase
  ARM: exynos: Correct the help text for platform Kconfig option
  ARM: bcm: Select ARM_AMBA for ARCH_BRCMSTB
  ARM: brcmstb: Add debug UART entry for 7216
  ...

Pull compat-ioctl fix from Arnd Bergmann:
 "One patch in the compat-ioctl series broke 32-bit rootfs for multiple
  people testing on 64-bit kernels. Let's fix it in -rc1 before others
  run into the same issue"

* tag 'compat-ioctl-fix' of git://git.kernel.org:/pub/scm/linux/kernel/git/arnd/playground:
  compat_ioctl: fix FIONREAD on devices

Pull vfs file system parameter updates from Al Viro:
 "Saner fs_parser.c guts and data structures. The system-wide registry
  of syntax types (string/enum/int32/oct32/.../etc.) is gone and so is
  the horror switch() in fs_parse() that would have to grow another case
  every time something got added to that system-wide registry.

  New syntax types can be added by filesystems easily now, and their
  namespace is that of functions - not of system-wide enum members. IOW,
  they can be shared or kept private and if some turn out to be widely
  useful, we can make them common library helpers, etc., without having
  to do anything whatsoever to fs_parse() itself.

  And we already get that kind of requests - the thing that finally
  pushed me into doing that was "oh, and let's add one for timeouts -
  things like 15s or 2h". If some filesystem really wants that, let them
  do it. Without somebody having to play gatekeeper for the variants
  blessed by direct support in fs_parse(), TYVM.

  Quite a bit of boilerplate is gone. And IMO the data structures make a
  lot more sense now. -200LoC, while we are at it"

* 'merge.nfs-fs_parse.1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (25 commits)
  tmpfs: switch to use of invalfc()
  cgroup1: switch to use of errorfc() et.al.
  procfs: switch to use of invalfc()
  hugetlbfs: switch to use of invalfc()
  cramfs: switch to use of errofc() et.al.
  gfs2: switch to use of errorfc() et.al.
  fuse: switch to use errorfc() et.al.
  ceph: use errorfc() and friends instead of spelling the prefix out
  prefix-handling analogues of errorf() and friends
  turn fs_param_is_... into functions
  fs_parse: handle optional arguments sanely
  fs_parse: fold fs_parameter_desc/fs_parameter_spec
  fs_parser: remove fs_parameter_description name field
  add prefix to fs_context->log
  ceph_parse_param(), ceph_parse_mon_ips(): switch to passing fc_log
  new primitive: __fs_parse()
  switch rbd and libceph to p_log-based primitives
  struct p_log, variants of warnf() et.al. taking that one instead
  teach logfc() to handle prefices, give it saner calling conventions
  get rid of cg_invalf()
  ...

Pull misc vfs updates from Al Viro:

 - bmap series from cmaiolino

 - getting rid of convolutions in copy_mount_options() (use a couple of
   copy_from_user() instead of the __get_user() crap)

* 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  saner copy_mount_options()
  fibmap: Reject negative block numbers
  fibmap: Use bmap instead of ->bmap method in ioctl_fibmap
  ecryptfs: drop direct calls to ->bmap
  cachefiles: drop direct usage of ->bmap method.
  fs: Enable bmap() function to properly return errors

Merge thundering herd avoidance on pipe IO.

This would have been applied for 5.5 already, but got delayed because of
a user-space race condition in the GNU make jobserver code.  Now that
there's a new GNU make 4.3 release, and most distributions seem to have
at least applied the (almost three year old) fix for the problem, let's
see if people notice.

And it might have been just bad random timing luck on my machine.

If you do hit the race condition, things will still work, but the
symptom is that you don't get nearly the expected parallelism when using
"make -j<N>".

The jobserver bug can definitely happen without this patch too, but
seems to be easier to trigger when we no longer wake up pipe waiters
unnecessarily.

* pipe-exclusive-wakeup:
  pipe: use exclusive waits when reading or writing

This makes the pipe code use separate wait-queues and exclusive waiting
for readers and writers, avoiding a nasty thundering herd problem when
there are lots of readers waiting for data on a pipe (or, less commonly,
lots of writers waiting for a pipe to have space).

While this isn't a common occurrence in the traditional "use a pipe as a
data transport" case, where you typically only have a single reader and
a single writer process, there is one common special case: using a pipe
as a source of "locking tokens" rather than for data communication.

In particular, the GNU make jobserver code ends up using a pipe as a way
to limit parallelism, where each job consumes a token by reading a byte
from the jobserver pipe, and releases the token by writing a byte back
to the pipe.

This pattern is fairly traditional on Unix, and works very well, but
will waste a lot of time waking up a lot of processes when only a single
reader needs to be woken up when a writer releases a new token.

A simplified test-case of just this pipe interaction is to create 64
processes, and then pass a single token around between them (this
test-case also intentionally passes another token that gets ignored to
test the "wake up next" logic too, in case anybody wonders about it):

    #include <unistd.h>

    int main(int argc, char **argv)
    {
        int fd[2], counters[2];

        pipe(fd);
        counters[0] = 0;
        counters[1] = -1;
        write(fd[1], counters, sizeof(counters));

        /* 64 processes */
        fork(); fork(); fork(); fork(); fork(); fork();

        do {
                int i;
                read(fd[0], &i, sizeof(i));
                if (i < 0)
                        continue;
                counters[0] = i+1;
                write(fd[1], counters, (1+(i & 1)) *sizeof(int));
        } while (counters[0] < 1000000);
        return 0;
    }

and in a perfect world, passing that token around should only cause one
context switch per transfer, when the writer of a token causes a
directed wakeup of just a single reader.

But with the "writer wakes all readers" model we traditionally had, on
my test box the above case causes more than an order of magnitude more
scheduling: instead of the expected ~1M context switches, "perf stat"
shows

        231,852.37 msec task-clock                #   15.857 CPUs utilized
        11,250,961      context-switches          #    0.049 M/sec
           616,304      cpu-migrations            #    0.003 M/sec
             1,648      page-faults               #    0.007 K/sec
 1,097,903,998,514      cycles                    #    4.735 GHz
   120,781,778,352      instructions              #    0.11  insn per cycle
    27,997,056,043      branches                  #  120.754 M/sec
       283,581,233      branch-misses             #    1.01% of all branches

      14.621273891 seconds time elapsed

       0.018243000 seconds user
       3.611468000 seconds sys

before this commit.

After this commit, I get

          5,229.55 msec task-clock                #    3.072 CPUs utilized
         1,212,233      context-switches          #    0.232 M/sec
           103,951      cpu-migrations            #    0.020 M/sec
             1,328      page-faults               #    0.254 K/sec
    21,307,456,166      cycles                    #    4.074 GHz
    12,947,819,999      instructions              #    0.61  insn per cycle
     2,881,985,678      branches                  #  551.096 M/sec
        64,267,015      branch-misses             #    2.23% of all branches

       1.702148350 seconds time elapsed

       0.004868000 seconds user
       0.110786000 seconds sys

instead. Much better.

[ Note! This kernel improvement seems to be very good at triggering a
  race condition in the make jobserver (in GNU make 4.2.1) for me. It's
  a long known bug that was fixed back in June 2017 by GNU make commit
  b552b0525198 ("[SV 51159] Use a non-blocking read with pselect to
  avoid hangs.").

  But there wasn't a new release of GNU make until 4.3 on Jan 19 2020,
  so a number of distributions may still have the buggy version. Some
  have backported the fix to their 4.2.1 release, though, and even
  without the fix it's quite timing-dependent whether the bug actually
  is hit. ]

Josh Triplett says:
 "I've been hammering on your pipe fix patch (switching to exclusive
  wait queues) for a month or so, on several different systems, and I've
  run into no issues with it. The patch *substantially* improves
  parallel build times on large (~100 CPU) systems, both with parallel
  make and with other things that use make's pipe-based jobserver.

  All current distributions (including stable and long-term stable
  distributions) have versions of GNU make that no longer have the
  jobserver bug"
Tested-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>