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: 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
  2. 09 May, 2017 1 commit
  3. 16 Jun, 2015 1 commit
    • Paul Gortmaker's avatar
      lib/list_sort: use late_initcall to hook in self tests · 4c7217f1
      Paul Gortmaker authored
      This was using module_init, but there is no way this code can
      be modular.  In the non-modular case, a module_init becomes a
      device_initcall, but this really isn't a device.   So we should
      choose a more appropriate initcall bucket to put it in.
      
      Assuming boot time self tests need to be observed over a console
      to be useful, and that the console device could possibly not be
      fully functional until after device_initcall, we move this to the
      late_initcall bucket, which is immediately after device_initcall.
      
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarPaul Gortmaker <paul.gortmaker@windriver.com>
      4c7217f1
  4. 13 Feb, 2015 1 commit
    • Rasmus Villemoes's avatar
      lib/list_sort.c: rearrange includes · 7259fa04
      Rasmus Villemoes authored
      Memory allocation only happens in the self test, just as random numbers
      are only used there.  So move the inclusion of slab.h inside the
      CONFIG_TEST_LIST_SORT.
      
      We don't need module.h and all of the stuff it carries with it, so replace
      with export.h and compiler.h.  Unfortunately, the ARRAY_SIZE macro from
      kernel.h requires the user to ensure bug.h is also included (for
      BUILD_BUG_ON_ZERO, used by __must_be_array).  We used to get that through
      some maze of nested includes, but just include it explicitly.
      
      linux/string.h is then only included implicitly through
      kernel.h->printk.h->dynamic_debug.h, but only if !CONFIG_DYNAMIC_DEBUG, so
      just include it explicitly (for memset).
      
      objdump -d says the generated code is the same, and wc -l says that
      lib/.list_sort.o.cmd went from 579 to 165 lines.
      Signed-off-by: default avatarRasmus Villemoes <linux@rasmusvillemoes.dk>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      7259fa04
  5. 07 Aug, 2014 5 commits
  6. 30 Apr, 2013 1 commit
  7. 26 Oct, 2010 6 commits
  8. 01 Oct, 2010 1 commit
  9. 06 Mar, 2010 2 commits
    • Don Mullis's avatar
      lib: revise list_sort() header comment · 02b12b7a
      Don Mullis authored
      Clarify and correct header comment of list_sort().
      Signed-off-by: default avatarDon Mullis <don.mullis@gmail.com>
      Cc: Dave Airlie <airlied@redhat.com>
      Cc: Andi Kleen <andi@firstfloor.org>
      Cc: Dave Chinner <david@fromorbit.com>
      Cc: Artem Bityutskiy <dedekind@infradead.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      02b12b7a
    • Don Mullis's avatar
      lib: more scalable list_sort() · 835cc0c8
      Don Mullis authored
      XFS and UBIFS can pass long lists to list_sort(); this alternative
      implementation scales better, reaching ~3x performance gain when list
      length exceeds the L2 cache size.
      
      Stand-alone program timings were run on a Core 2 duo L1=32KB L2=4MB,
      gcc-4.4, with flags extracted from an Ubuntu kernel build.  Object size is
      581 bytes compared to 455 for Mark J.  Roberts' code.
      
      Worst case for either implementation is a list length just over a power of
      two, and to roughly the same degree, so here are timing results for a
      range of 2^N+1 lengths.  List elements were 16 bytes each including malloc
      overhead; initial order was random.
      
                            time (msec)
                            Tatham-Roberts
                            |       generic-Mullis-v2
      loop_count  length    |       |    ratio
      4000000       2     206     294    1.427
      2000000       3     176     227    1.289
      1000000       5     199     172    0.864
       500000       9     235     178    0.757
       250000      17     243     182    0.748
       125000      33     261     196    0.750
        62500      65     277     209    0.754
        31250     129     292     219    0.75
        15625     257     317     235    0.741
         7812     513     340     252    0.741
         3906    1025     362     267    0.737
         1953    2049     388     283    0.729  ~ L1 size
          976    4097     556     323    0.580
          488    8193     678     361    0.532
          244   16385     773     395    0.510
          122   32769     844     418    0.495
           61   65537     917     454    0.495
           30  131073    1128     543    0.481
           15  262145    2355     869    0.369  ~ L2 size
            7  524289    5597    1714    0.306
            3 1048577    6218    2022    0.325
      
      Mark's code does not actually implement the usual or generic mergesort,
      but rather a variant from Simon Tatham described here:
      
          http://www.chiark.greenend.org.uk/~sgtatham/algorithms/listsort.html
      
      Simon's algorithm performs O(log N) passes over the entire input list,
      doing merges of sublists that double in size on each pass.  The generic
      algorithm instead merges pairs of equal length lists as early as possible,
      in recursive order.  For either algorithm, the elements that extend the
      list beyond power-of-two length are a special case, handled as nearly as
      possible as a "rounding-up" to a full POT.
      
      Some intuition for the locality of reference implications of merge order
      may be gotten by watching this animation:
      
          http://www.sorting-algorithms.com/merge-sort
      
      Simon's algorithm requires only O(1) extra space rather than the generic
      algorithm's O(log N), but in my non-recursive implementation the actual
      O(log N) data is merely a vector of ~20 pointers, which I've put on the
      stack.
      
      Long-running list_sort() calls: If the list passed in may be long, or the
      client's cmp() callback function is slow, the client's cmp() may
      periodically invoke cond_resched() to voluntarily yield the CPU.  All
      inner loops of list_sort() call back to cmp().
      
      Stability of the sort: distinct elements that compare equal emerge from
      the sort in the same order as with Mark's code, for simple test cases.  A
      boot-time test is provided to verify this and other correctness
      requirements.
      
      A kernel that uses drm.ko appears to run normally with this change; I have
      no suitable hardware to similarly test the use by UBIFS.
      
      [akpm@linux-foundation.org: style tweaks, fix comment, make list_sort_test __init]
      Signed-off-by: default avatarDon Mullis <don.mullis@gmail.com>
      Cc: Dave Airlie <airlied@redhat.com>
      Cc: Andi Kleen <andi@firstfloor.org>
      Cc: Dave Chinner <david@fromorbit.com>
      Cc: Artem Bityutskiy <dedekind@infradead.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      835cc0c8
  10. 13 Jan, 2010 1 commit