1. 09 Dec, 2017 1 commit
  2. 02 Nov, 2017 1 commit
    • Greg Kroah-Hartman's avatar
      License cleanup: add SPDX GPL-2.0 license identifier to files with no license · b2441318
      Greg Kroah-Hartman authored
      Many source files in the tree are missing licensing information, which
      makes it harder for compliance tools to determine the correct license.
      
      By default all files without license information are under the default
      license of the kernel, which is GPL version 2.
      
      Update the files which contain no license information with the 'GPL-2.0'
      SPDX license identifier.  The SPDX identifier is a legally binding
      shorthand, which can be used instead of the full boiler plate text.
      
      This patch is based on work done by Thomas Gleixner and Kate Stewart and
      Philippe Ombredanne.
      
      How this work was done:
      
      Patches were generated and checked against linux-4.14-rc6 for a subset of
      the use cases:
       - file had no licensing information it it.
       - file was a */uapi/* one with no licensing information in it,
       - file was a */uapi/* one with existing licensing information,
      
      Further patches will be generated in subsequent months to fix up cases
      where non-standard license headers were used, and references to license
      had to be inferred by heuristics based on keywords.
      
      The analysis to determine which SPDX License Identifier to be applied to
      a file was done in a spreadsheet of side by side results from of the
      output of two independent scanners (ScanCode & Windriver) producing SPDX
      tag:value files created by Philippe Ombredanne.  Philippe prepared the
      base worksheet, and did an initial spot review of a few 1000 files.
      
      The 4.13 kernel was the starting point of the analysis with 60,537 files
      assessed.  Kate Stewart did a file by file comparison of the scanner
      results in the spreadsheet to determine which SPDX license identifier(s)
      to be applied to the file. She confirmed any determination that was not
      immediately clear with lawyers working with the Linux Foundation.
      
      Criteria used to select files for SPDX license identifier tagging was:
       - Files considered eligible had to be source code files.
       - Make and config files were included as candidates if they contained >5
         lines of source
       - File already had some variant of a license header in it (even if <5
         lines).
      
      All documentation files were explicitly excluded.
      
      The following heuristics were used to determine which SPDX license
      identifiers to apply.
      
       - when both scanners couldn't find any license traces, file was
         considered to have no license information in it, and the top level
         COPYING file license applied.
      
         For non */uapi/* files that summary was:
      
         SPDX license identifier                            # files
         ---------------------------------------------------|-------
         GPL-2.0                                              11139
      
         and resulted in the first patch in this series.
      
         If that file was a */uapi/* path one, it was "GPL-2.0 WITH
         Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:
      
         SPDX license identifier                            # files
         ---------------------------------------------------|-------
         GPL-2.0 WITH Linux-syscall-note                        930
      
         and resulted in the second patch in this series.
      
       - if a file had some form of licensing information in it, and was one
         of the */uapi/* ones, it was denoted with the Linux-syscall-note if
         any GPL family license was found in the file or had no licensing in
         it (per prior point).  Results summary:
      
         SPDX license identifier                            # files
         ---------------------------------------------------|------
         GPL-2.0 WITH Linux-syscall-note                       270
         GPL-2.0+ WITH Linux-syscall-note                      169
         ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
         ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
         LGPL-2.1+ WITH Linux-syscall-note                      15
         GPL-1.0+ WITH Linux-syscall-note                       14
         ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
         LGPL-2.0+ WITH Linux-syscall-note                       4
         LGPL-2.1 WITH Linux-syscall-note                        3
         ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
         ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1
      
         and that resulted in the third patch in this series.
      
       - when the two scanners agreed on the detected license(s), that became
         the concluded license(s).
      
       - when there was disagreement between the two scanners (one detected a
         license but the other didn't, or they both detected different
         licenses) a manual inspection of the file occurred.
      
       - In most cases a manual inspection of the information in the file
         resulted in a clear resolution of the license that should apply (and
         which scanner probably needed to revisit its heuristics).
      
       - When it was not immediately clear, the license identifier was
         confirmed with lawyers working with the Linux Foundation.
      
       - If there was any question as to the appropriate license identifier,
         the file was flagged for further research and to be revisited later
         in time.
      
      In total, over 70 hours of logged manual review was done on the
      spreadsheet to determine the SPDX license identifiers to apply to the
      source files by Kate, Philippe, Thomas and, in some cases, confirmation
      by lawyers working with the Linux Foundation.
      
      Kate also obtained a third independent scan of the 4.13 code base from
      FOSSology, and compared selected files where the other two scanners
      disagreed against that SPDX file, to see if there was new insights.  The
      Windriver scanner is based on an older version of FOSSology in part, so
      they are related.
      
      Thomas did random spot checks in about 500 files from the spreadsheets
      for the uapi headers and agreed with SPDX license identifier in the
      files he inspected. For the non-uapi files Thomas did random spot checks
      in about 15000 files.
      
      In initial set of patches against 4.14-rc6, 3 files were found to have
      copy/paste license identifier errors, and have been fixed to reflect the
      correct identifier.
      
      Additionally Philippe spent 10 hours this week doing a detailed manual
      inspection and review of the 12,461 patched files from the initial patch
      version early this week with:
       - a full scancode scan run, collecting the matched texts, detected
         license ids and scores
       - reviewing anything where there was a license detected (about 500+
         files) to ensure that the applied SPDX license was correct
       - reviewing anything where there was no detection but the patch license
         was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
         SPDX license was correct
      
      This produced a worksheet with 20 files needing minor correction.  This
      worksheet was then exported into 3 different .csv files for the
      different types of files to be modified.
      
      These .csv files were then reviewed by Greg.  Thomas wrote a script to
      parse the csv files and add the proper SPDX tag to the file, in the
      format that the file expected.  This script was further refined by Greg
      based on the output to detect more types of files automatically and to
      distinguish between header and source .c files (which need different
      comment types.)  Finally Greg ran the script using the .csv files to
      generate the patches.
      Reviewed-by: default avatarKate Stewart <kstewart@linuxfoundation.org>
      Reviewed-by: default avatarPhilippe Ombredanne <pombredanne@nexb.com>
      Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      b2441318
  3. 14 Apr, 2017 2 commits
  4. 03 Mar, 2017 1 commit
  5. 25 Dec, 2016 1 commit
  6. 29 Nov, 2016 1 commit
    • Joel Fernandes's avatar
      timekeeping: Add a fast and NMI safe boot clock · 948a5312
      Joel Fernandes authored
      This boot clock can be used as a tracing clock and will account for
      suspend time.
      
      To keep it NMI safe since we're accessing from tracing, we're not using a
      separate timekeeper with updates to monotonic clock and boot offset
      protected with seqlocks. This has the following minor side effects:
      
      (1) Its possible that a timestamp be taken after the boot offset is updated
      but before the timekeeper is updated. If this happens, the new boot offset
      is added to the old timekeeping making the clock appear to update slightly
      earlier:
         CPU 0                                        CPU 1
         timekeeping_inject_sleeptime64()
         __timekeeping_inject_sleeptime(tk, delta);
                                                      timestamp();
         timekeeping_update(tk, TK_CLEAR_NTP...);
      
      (2) On 32-bit systems, the 64-bit boot offset (tk->offs_boot) may be
      partially updated.  Since the tk->offs_boot update is a rare event, this
      should be a rare occurrence which postprocessing should be able to handle.
      Signed-off-by: default avatarJoel Fernandes <joelaf@google.com>
      Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
      Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Cc: Prarit Bhargava <prarit@redhat.com>
      Cc: Richard Cochran <richardcochran@gmail.com>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Link: http://lkml.kernel.org/r/1480372524-15181-6-git-send-email-john.stultz@linaro.orgSigned-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      948a5312
  7. 22 Sep, 2016 1 commit
  8. 01 Jun, 2016 1 commit
  9. 22 Apr, 2016 1 commit
    • Baolin Wang's avatar
      time: Introduce do_sys_settimeofday64() · 86d34732
      Baolin Wang authored
      The do_sys_settimeofday() function uses a timespec, which is not year
      2038 safe on 32bit systems.
      
      Thus this patch introduces do_sys_settimeofday64(), which allows us to
      transition users of do_sys_settimeofday() to using 64bit time types.
      
      Cc: Prarit Bhargava <prarit@redhat.com>
      Cc: Richard Cochran <richardcochran@gmail.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@kernel.org>
      Signed-off-by: default avatarBaolin Wang <baolin.wang@linaro.org>
      [jstultz: Include errno-base.h to avoid build issue on some arches]
      Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
      86d34732
  10. 03 Mar, 2016 3 commits
    • Christopher S. Hall's avatar
      time: Add history to cross timestamp interface supporting slower devices · 2c756feb
      Christopher S. Hall authored
      Another representative use case of time sync and the correlated
      clocksource (in addition to PTP noted above) is PTP synchronized
      audio.
      
      In a streaming application, as an example, samples will be sent and/or
      received by multiple devices with a presentation time that is in terms
      of the PTP master clock. Synchronizing the audio output on these
      devices requires correlating the audio clock with the PTP master
      clock. The more precise this correlation is, the better the audio
      quality (i.e. out of sync audio sounds bad).
      
      From an application standpoint, to correlate the PTP master clock with
      the audio device clock, the system clock is used as a intermediate
      timebase. The transforms such an application would perform are:
      
          System Clock <-> Audio clock
          System Clock <-> Network Device Clock [<-> PTP Master Clock]
      
      Modern Intel platforms can perform a more accurate cross timestamp in
      hardware (ART,audio device clock).  The audio driver requires
      ART->system time transforms -- the same as required for the network
      driver. These platforms offload audio processing (including
      cross-timestamps) to a DSP which to ensure uninterrupted audio
      processing, communicates and response to the host only once every
      millsecond. As a result is takes up to a millisecond for the DSP to
      receive a request, the request is processed by the DSP, the audio
      output hardware is polled for completion, the result is copied into
      shared memory, and the host is notified. All of these operation occur
      on a millisecond cadence.  This transaction requires about 2 ms, but
      under heavier workloads it may take up to 4 ms.
      
      Adding a history allows these slow devices the option of providing an
      ART value outside of the current interval. In this case, the callback
      provided is an accessor function for the previously obtained counter
      value. If get_system_device_crosststamp() receives a counter value
      previous to cycle_last, it consults the history provided as an
      argument in history_ref and interpolates the realtime and monotonic
      raw system time using the provided counter value. If there are any
      clock discontinuities, e.g. from calling settimeofday(), the monotonic
      raw time is interpolated in the usual way, but the realtime clock time
      is adjusted by scaling the monotonic raw adjustment.
      
      When an accessor function is used a history argument *must* be
      provided. The history is initialized using ktime_get_snapshot() and
      must be called before the counter values are read.
      
      Cc: Prarit Bhargava <prarit@redhat.com>
      Cc: Richard Cochran <richardcochran@gmail.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: kevin.b.stanton@intel.com
      Cc: kevin.j.clarke@intel.com
      Cc: hpa@zytor.com
      Cc: jeffrey.t.kirsher@intel.com
      Cc: netdev@vger.kernel.org
      Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Signed-off-by: default avatarChristopher S. Hall <christopher.s.hall@intel.com>
      [jstultz: Fixed up cycles_t/cycle_t type confusion]
      Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
      2c756feb
    • Christopher S. Hall's avatar
      time: Add driver cross timestamp interface for higher precision time synchronization · 8006c245
      Christopher S. Hall authored
      ACKNOWLEDGMENT: cross timestamp code was developed by Thomas Gleixner
      <tglx@linutronix.de>. It has changed considerably and any mistakes are
      mine.
      
      The precision with which events on multiple networked systems can be
      synchronized using, as an example, PTP (IEEE 1588, 802.1AS) is limited
      by the precision of the cross timestamps between the system clock and
      the device (timestamp) clock. Precision here is the degree of
      simultaneity when capturing the cross timestamp.
      
      Currently the PTP cross timestamp is captured in software using the
      PTP device driver ioctl PTP_SYS_OFFSET. Reads of the device clock are
      interleaved with reads of the realtime clock. At best, the precision
      of this cross timestamp is on the order of several microseconds due to
      software latencies. Sub-microsecond precision is required for
      industrial control and some media applications. To achieve this level
      of precision hardware supported cross timestamping is needed.
      
      The function get_device_system_crosstimestamp() allows device drivers
      to return a cross timestamp with system time properly scaled to
      nanoseconds.  The realtime value is needed to discipline that clock
      using PTP and the monotonic raw value is used for applications that
      don't require a "real" time, but need an unadjusted clock time.  The
      get_device_system_crosstimestamp() code calls back into the driver to
      ensure that the system counter is within the current timekeeping
      update interval.
      
      Modern Intel hardware provides an Always Running Timer (ART) which is
      exactly related to TSC through a known frequency ratio. The ART is
      routed to devices on the system and is used to precisely and
      simultaneously capture the device clock with the ART.
      
      Cc: Prarit Bhargava <prarit@redhat.com>
      Cc: Richard Cochran <richardcochran@gmail.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: kevin.b.stanton@intel.com
      Cc: kevin.j.clarke@intel.com
      Cc: hpa@zytor.com
      Cc: jeffrey.t.kirsher@intel.com
      Cc: netdev@vger.kernel.org
      Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Signed-off-by: default avatarChristopher S. Hall <christopher.s.hall@intel.com>
      [jstultz: Reworked to remove extra structures and simplify calling]
      Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
      8006c245
    • Christopher S. Hall's avatar
      time: Add timekeeping snapshot code capturing system time and counter · 9da0f49c
      Christopher S. Hall authored
      In the current timekeeping code there isn't any interface to
      atomically capture the current relationship between the system counter
      and system time. ktime_get_snapshot() returns this triple (counter,
      monotonic raw, realtime) in the system_time_snapshot struct.
      
      Cc: Prarit Bhargava <prarit@redhat.com>
      Cc: Richard Cochran <richardcochran@gmail.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: kevin.b.stanton@intel.com
      Cc: kevin.j.clarke@intel.com
      Cc: hpa@zytor.com
      Cc: jeffrey.t.kirsher@intel.com
      Cc: netdev@vger.kernel.org
      Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Signed-off-by: default avatarChristopher S. Hall <christopher.s.hall@intel.com>
      [jstultz: Moved structure definitions around to clean things up,
       fixed cycles_t/cycle_t confusion.]
      Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
      9da0f49c
  11. 01 Oct, 2015 1 commit
  12. 17 Aug, 2015 1 commit
  13. 09 Jul, 2015 1 commit
  14. 22 May, 2015 2 commits
    • Xunlei Pang's avatar
      time: Remove read_boot_clock() · e83d0a41
      Xunlei Pang authored
      Now that we have a read_boot_clock64() function available on every
      architecture, and converted all the users to it, it's time to remove
      the (now unused) read_boot_clock() completely from the kernel.
      
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@kernel.org>
      Signed-off-by: default avatarXunlei Pang <pang.xunlei@linaro.org>
      [jstultz: Minor commit message tweak suggested by Ingo]
      Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
      e83d0a41
    • Harald Geyer's avatar
      timekeeping: Provide new API to get the current time resolution · 6374f912
      Harald Geyer authored
      This patch series introduces a new function
      u32 ktime_get_resolution_ns(void)
      which allows to clean up some driver code.
      
      In particular the IIO subsystem has a function to provide timestamps for
      events but no means to get their resolution. So currently the dht11 driver
      tries to guess the resolution in a rather messy and convoluted way. We
      can do much better with the new code.
      
      This API is not designed to be exposed to user space.
      
      This has been tested on i386, sunxi and mxs.
      
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@kernel.org>
      Signed-off-by: default avatarHarald Geyer <harald@ccbib.org>
      [jstultz: Tweaked to make it build after upstream changes]
      Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
      6374f912
  15. 03 Apr, 2015 4 commits
  16. 27 Mar, 2015 2 commits
  17. 24 Jan, 2015 2 commits
  18. 21 Nov, 2014 5 commits
  19. 29 Oct, 2014 2 commits
  20. 23 Jul, 2014 7 commits