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. 17 Apr, 2017 1 commit
  3. 15 Feb, 2017 1 commit
  4. 09 Dec, 2016 3 commits
    • Steven Rostedt (Red Hat)'s avatar
      tracing: Allow benchmark to be enabled at early_initcall() · 9c1f6bb8
      Steven Rostedt (Red Hat) authored
      The trace event start up selftests fails when the trace benchmark is
      enabled, because it is disabled during boot. It really only needs to be
      disabled before scheduling is set up, as it creates a thread.
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      9c1f6bb8
    • Steven Rostedt (Red Hat)'s avatar
      tracing: Do not start benchmark on boot up · 1dd349ab
      Steven Rostedt (Red Hat) authored
      Trace events are enabled very early on boot up via the boot command line
      parameter. The benchmark tool creates a new thread to perform the trace
      event benchmarking. But at start up, it is called before scheduling is set
      up and because it creates a new thread before the init thread is created,
      this crashes the kernel.
      
      Have the benchmark fail to register when started via the kernel command
      line.
      
      Also, since the registering of a tracepoint now can handle failure cases,
      return -ENOMEM instead of warning if the thread cannot be created.
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      1dd349ab
    • Steven Rostedt (Red Hat)'s avatar
      tracing: Have the reg function allow to fail · 8cf868af
      Steven Rostedt (Red Hat) authored
      Some tracepoints have a registration function that gets enabled when the
      tracepoint is enabled. There may be cases that the registraction function
      must fail (for example, can't allocate enough memory). In this case, the
      tracepoint should also fail to register, otherwise the user would not know
      why the tracepoint is not working.
      
      Cc: David Howells <dhowells@redhat.com>
      Cc: Seiji Aguchi <seiji.aguchi@hds.com>
      Cc: Anton Blanchard <anton@samba.org>
      Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      8cf868af
  5. 02 Nov, 2015 1 commit
  6. 06 Jun, 2014 2 commits
  7. 04 Jun, 2014 1 commit
  8. 30 May, 2014 1 commit
    • Steven Rostedt (Red Hat)'s avatar
      tracing: Add tracepoint benchmark tracepoint · 81dc9f0e
      Steven Rostedt (Red Hat) authored
      In order to help benchmark the time tracepoints take, a new config
      option is added called CONFIG_TRACEPOINT_BENCHMARK. When this option
      is set a tracepoint is created called "benchmark:benchmark_event".
      When the tracepoint is enabled, it kicks off a kernel thread that
      goes into an infinite loop (calling cond_sched() to let other tasks
      run), and calls the tracepoint. Each iteration will record the time
      it took to write to the tracepoint and the next iteration that
      data will be passed to the tracepoint itself. That is, the tracepoint
      will report the time it took to do the previous tracepoint.
      The string written to the tracepoint is a static string of 128 bytes
      to keep the time the same. The initial string is simply a write of
      "START". The second string records the cold cache time of the first
      write which is not added to the rest of the calculations.
      
      As it is a tight loop, it benchmarks as hot cache. That's fine because
      we care most about hot paths that are probably in cache already.
      
      An example of the output:
      
           START
           first=3672 [COLD CACHED]
           last=632 first=3672 max=632 min=632 avg=316 std=446 std^2=199712
           last=278 first=3672 max=632 min=278 avg=303 std=316 std^2=100337
           last=277 first=3672 max=632 min=277 avg=296 std=258 std^2=67064
           last=273 first=3672 max=632 min=273 avg=292 std=224 std^2=50411
           last=273 first=3672 max=632 min=273 avg=288 std=200 std^2=40389
           last=281 first=3672 max=632 min=273 avg=287 std=183 std^2=33666
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      81dc9f0e