1. 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: 's avatarKate Stewart <kstewart@linuxfoundation.org>
      Reviewed-by: 's avatarPhilippe Ombredanne <pombredanne@nexb.com>
      Reviewed-by: 's avatarThomas Gleixner <tglx@linutronix.de>
      Signed-off-by: 's avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      b2441318
  2. 19 Apr, 2017 1 commit
  3. 28 Mar, 2017 1 commit
    • Shaohua Li's avatar
      block: track request size in blk_issue_stat · 88eeca49
      Shaohua Li authored
      Currently there is no way to know the request size when the request is
      finished. Next patch will need this info. We could add extra field to
      record the size, but blk_issue_stat has enough space to record it, so
      this patch just overloads blk_issue_stat. With this, we will have 49bits
      to track time, which still is very long time.
      Signed-off-by: 's avatarShaohua Li <shli@fb.com>
      Signed-off-by: 's avatarJens Axboe <axboe@fb.com>
      88eeca49
  4. 21 Mar, 2017 1 commit
    • Omar Sandoval's avatar
      blk-stat: convert to callback-based statistics reporting · 34dbad5d
      Omar Sandoval authored
      Currently, statistics are gathered in ~0.13s windows, and users grab the
      statistics whenever they need them. This is not ideal for both in-tree
      users:
      
      1. Writeback throttling wants its own dynamically sized window of
         statistics. Since the blk-stats statistics are reset after every
         window and the wbt windows don't line up with the blk-stats windows,
         wbt doesn't see every I/O.
      2. Polling currently grabs the statistics on every I/O. Again, depending
         on how the window lines up, we may miss some I/Os. It's also
         unnecessary overhead to get the statistics on every I/O; the hybrid
         polling heuristic would be just as happy with the statistics from the
         previous full window.
      
      This reworks the blk-stats infrastructure to be callback-based: users
      register a callback that they want called at a given time with all of
      the statistics from the window during which the callback was active.
      Users can dynamically bucketize the statistics. wbt and polling both
      currently use read vs. write, but polling can be extended to further
      subdivide based on request size.
      
      The callbacks are kept on an RCU list, and each callback has percpu
      stats buffers. There will only be a few users, so the overhead on the
      I/O completion side is low. The stats flushing is also simplified
      considerably: since the timer function is responsible for clearing the
      statistics, we don't have to worry about stale statistics.
      
      wbt is a trivial conversion. After the conversion, the windowing problem
      mentioned above is fixed.
      
      For polling, we register an extra callback that caches the previous
      window's statistics in the struct request_queue for the hybrid polling
      heuristic to use.
      
      Since we no longer have a single stats buffer for the request queue,
      this also removes the sysfs and debugfs stats entries. To replace those,
      we add a debugfs entry for the poll statistics.
      Signed-off-by: 's avatarOmar Sandoval <osandov@fb.com>
      Signed-off-by: 's avatarJens Axboe <axboe@fb.com>
      34dbad5d
  5. 28 Nov, 2016 3 commits
  6. 11 Nov, 2016 2 commits
  7. 10 Nov, 2016 1 commit
    • Jens Axboe's avatar
      blk-wbt: add general throttling mechanism · e34cbd30
      Jens Axboe authored
      We can hook this up to the block layer, to help throttle buffered
      writes.
      
      wbt registers a few trace points that can be used to track what is
      happening in the system:
      
      wbt_lat: 259:0: latency 2446318
      wbt_stat: 259:0: rmean=2446318, rmin=2446318, rmax=2446318, rsamples=1,
                     wmean=518866, wmin=15522, wmax=5330353, wsamples=57
      wbt_step: 259:0: step down: step=1, window=72727272, background=8, normal=16, max=32
      
      This shows a sync issue event (wbt_lat) that exceeded it's time. wbt_stat
      dumps the current read/write stats for that window, and wbt_step shows a
      step down event where we now scale back writes. Each trace includes the
      device, 259:0 in this case.
      Signed-off-by: 's avatarJens Axboe <axboe@fb.com>
      e34cbd30