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 <[email protected]>
      Reviewed-by: default avatarPhilippe Ombredanne <[email protected]>
      Reviewed-by: default avatarThomas Gleixner <[email protected]>
      Signed-off-by: default avatarGreg Kroah-Hartman <[email protected]>
      b2441318
  2. 01 Oct, 2017 1 commit
  3. 02 Mar, 2017 1 commit
  4. 27 Jan, 2017 1 commit
  5. 20 Jan, 2017 1 commit
    • Jens Axboe's avatar
      blk-mq: allow resize of scheduler requests · 70f36b60
      Jens Axboe authored
      Add support for growing the tags associated with a hardware queue, for
      the scheduler tags. Currently we only support resizing within the
      limits of the original depth, change that so we can grow it as well by
      allocating and replacing the existing scheduler tag set.
      
      This is similar to how we could increase the software queue depth with
      the legacy IO stack and schedulers.
      Signed-off-by: default avatarJens Axboe <[email protected]>
      Reviewed-by: default avatarOmar Sandoval <[email protected]>
      70f36b60
  6. 17 Jan, 2017 2 commits
  7. 17 Sep, 2016 4 commits
  8. 15 Sep, 2016 1 commit
  9. 01 Oct, 2015 1 commit
  10. 15 Aug, 2015 1 commit
    • Ming Lei's avatar
      blk-mq: fix race between timeout and freeing request · 0048b483
      Ming Lei authored
      Inside timeout handler, blk_mq_tag_to_rq() is called
      to retrieve the request from one tag. This way is obviously
      wrong because the request can be freed any time and some
      fiedds of the request can't be trusted, then kernel oops
      might be triggered[1].
      
      Currently wrt. blk_mq_tag_to_rq(), the only special case is
      that the flush request can share same tag with the request
      cloned from, and the two requests can't be active at the same
      time, so this patch fixes the above issue by updating tags->rqs[tag]
      with the active request(either flush rq or the request cloned
      from) of the tag.
      
      Also blk_mq_tag_to_rq() gets much simplified with this patch.
      
      Given blk_mq_tag_to_rq() is mainly for drivers and the caller must
      make sure the request can't be freed, so in bt_for_each() this
      helper is replaced with tags->rqs[tag].
      
      [1] kernel oops log
      [  439.696220] BUG: unable to handle kernel NULL pointer dereference at 0000000000000158^M
      [  439.697162] IP: [<ffffffff812d89ba>] blk_mq_tag_to_rq+0x21/0x6e^M
      [  439.700653] PGD 7ef765067 PUD 7ef764067 PMD 0 ^M
      [  439.700653] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC ^M
      [  439.700653] Dumping ftrace buffer:^M
      [  439.700653]    (ftrace buffer empty)^M
      [  439.700653] Modules linked in: nbd ipv6 kvm_intel kvm serio_raw^M
      [  439.700653] CPU: 6 PID: 2779 Comm: stress-ng-sigfd Not tainted 4.2.0-rc5-next-20150805+ #265^M
      [  439.730500] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011^M
      [  439.730500] task: ffff880605308000 ti: ffff88060530c000 task.ti: ffff88060530c000^M
      [  439.730500] RIP: 0010:[<ffffffff812d89ba>]  [<ffffffff812d89ba>] blk_mq_tag_to_rq+0x21/0x6e^M
      [  439.730500] RSP: 0018:ffff880819203da0  EFLAGS: 00010283^M
      [  439.730500] RAX: ffff880811b0e000 RBX: ffff8800bb465f00 RCX: 0000000000000002^M
      [  439.730500] RDX: 0000000000000000 RSI: 0000000000000202 RDI: 0000000000000000^M
      [  439.730500] RBP: ffff880819203db0 R08: 0000000000000002 R09: 0000000000000000^M
      [  439.730500] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000202^M
      [  439.730500] R13: ffff880814104800 R14: 0000000000000002 R15: ffff880811a2ea00^M
      [  439.730500] FS:  00007f165b3f5740(0000) GS:ffff880819200000(0000) knlGS:0000000000000000^M
      [  439.730500] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b^M
      [  439.730500] CR2: 0000000000000158 CR3: 00000007ef766000 CR4: 00000000000006e0^M
      [  439.730500] Stack:^M
      [  439.730500]  0000000000000008 ffff8808114eed90 ffff880819203e00 ffffffff812dc104^M
      [  439.755663]  ffff880819203e40 ffffffff812d9f5e 0000020000000000 ffff8808114eed80^M
      [  439.755663] Call Trace:^M
      [  439.755663]  <IRQ> ^M
      [  439.755663]  [<ffffffff812dc104>] bt_for_each+0x6e/0xc8^M
      [  439.755663]  [<ffffffff812d9f5e>] ? blk_mq_rq_timed_out+0x6a/0x6a^M
      [  439.755663]  [<ffffffff812d9f5e>] ? blk_mq_rq_timed_out+0x6a/0x6a^M
      [  439.755663]  [<ffffffff812dc1b3>] blk_mq_tag_busy_iter+0x55/0x5e^M
      [  439.755663]  [<ffffffff812d88b4>] ? blk_mq_bio_to_request+0x38/0x38^M
      [  439.755663]  [<ffffffff812d8911>] blk_mq_rq_timer+0x5d/0xd4^M
      [  439.755663]  [<ffffffff810a3e10>] call_timer_fn+0xf7/0x284^M
      [  439.755663]  [<ffffffff810a3d1e>] ? call_timer_fn+0x5/0x284^M
      [  439.755663]  [<ffffffff812d88b4>] ? blk_mq_bio_to_request+0x38/0x38^M
      [  439.755663]  [<ffffffff810a46d6>] run_timer_softirq+0x1ce/0x1f8^M
      [  439.755663]  [<ffffffff8104c367>] __do_softirq+0x181/0x3a4^M
      [  439.755663]  [<ffffffff8104c76e>] irq_exit+0x40/0x94^M
      [  439.755663]  [<ffffffff81031482>] smp_apic_timer_interrupt+0x33/0x3e^M
      [  439.755663]  [<ffffffff815559a4>] apic_timer_interrupt+0x84/0x90^M
      [  439.755663]  <EOI> ^M
      [  439.755663]  [<ffffffff81554350>] ? _raw_spin_unlock_irq+0x32/0x4a^M
      [  439.755663]  [<ffffffff8106a98b>] finish_task_switch+0xe0/0x163^M
      [  439.755663]  [<ffffffff8106a94d>] ? finish_task_switch+0xa2/0x163^M
      [  439.755663]  [<ffffffff81550066>] __schedule+0x469/0x6cd^M
      [  439.755663]  [<ffffffff8155039b>] schedule+0x82/0x9a^M
      [  439.789267]  [<ffffffff8119b28b>] signalfd_read+0x186/0x49a^M
      [  439.790911]  [<ffffffff8106d86a>] ? wake_up_q+0x47/0x47^M
      [  439.790911]  [<ffffffff811618c2>] __vfs_read+0x28/0x9f^M
      [  439.790911]  [<ffffffff8117a289>] ? __fget_light+0x4d/0x74^M
      [  439.790911]  [<ffffffff811620a7>] vfs_read+0x7a/0xc6^M
      [  439.790911]  [<ffffffff8116292b>] SyS_read+0x49/0x7f^M
      [  439.790911]  [<ffffffff81554c17>] entry_SYSCALL_64_fastpath+0x12/0x6f^M
      [  439.790911] Code: 48 89 e5 e8 a9 b8 e7 ff 5d c3 0f 1f 44 00 00 55 89
      f2 48 89 e5 41 54 41 89 f4 53 48 8b 47 60 48 8b 1c d0 48 8b 7b 30 48 8b
      53 38 <48> 8b 87 58 01 00 00 48 85 c0 75 09 48 8b 97 88 0c 00 00 eb 10
      ^M
      [  439.790911] RIP  [<ffffffff812d89ba>] blk_mq_tag_to_rq+0x21/0x6e^M
      [  439.790911]  RSP <ffff880819203da0>^M
      [  439.790911] CR2: 0000000000000158^M
      [  439.790911] ---[ end trace d40af58949325661 ]---^M
      
      Cc: <[email protected]>
      Signed-off-by: default avatarMing Lei <[email protected]>
      Signed-off-by: default avatarJens Axboe <[email protected]>
      0048b483
  11. 01 Jun, 2015 1 commit
    • Keith Busch's avatar
      blk-mq: Shared tag enhancements · f26cdc85
      Keith Busch authored
      Storage controllers may expose multiple block devices that share hardware
      resources managed by blk-mq. This patch enhances the shared tags so a
      low-level driver can access the shared resources not tied to the unshared
      h/w contexts. This way the LLD can dynamically add and delete disks and
      request queues without having to track all the request_queue hctx's to
      iterate outstanding tags.
      Signed-off-by: Keith Busch's avatarKeith Busch <[email protected]>
      Signed-off-by: default avatarJens Axboe <[email protected]>
      f26cdc85
  12. 23 Jan, 2015 1 commit
  13. 31 Dec, 2014 1 commit
  14. 18 Jun, 2014 1 commit
  15. 04 Jun, 2014 1 commit
  16. 28 May, 2014 1 commit
    • Christoph Hellwig's avatar
      blk-mq: remove blk_mq_wait_for_tags · a3bd7756
      Christoph Hellwig authored
      The current logic for blocking tag allocation is rather confusing, as we
      first allocated and then free again a tag in blk_mq_wait_for_tags, just
      to attempt a non-blocking allocation and then repeat if someone else
      managed to grab the tag before us.
      
      Instead change blk_mq_alloc_request_pinned to simply do a blocking tag
      allocation itself and use the request we get back from it.
      Signed-off-by: default avatarChristoph Hellwig <[email protected]>
      Signed-off-by: default avatarJens Axboe <[email protected]>
      a3bd7756
  17. 23 May, 2014 1 commit
  18. 20 May, 2014 1 commit
    • Jens Axboe's avatar
      blk-mq: allow changing of queue depth through sysfs · e3a2b3f9
      Jens Axboe authored
      For request_fn based devices, the block layer exports a 'nr_requests'
      file through sysfs to allow adjusting of queue depth on the fly.
      Currently this returns -EINVAL for blk-mq, since it's not wired up.
      Wire this up for blk-mq, so that it now also always dynamic
      adjustments of the allowed queue depth for any given block device
      managed by blk-mq.
      Signed-off-by: default avatarJens Axboe <[email protected]>
      e3a2b3f9
  19. 19 May, 2014 1 commit
  20. 13 May, 2014 1 commit
    • Jens Axboe's avatar
      blk-mq: improve support for shared tags maps · 0d2602ca
      Jens Axboe authored
      This adds support for active queue tracking, meaning that the
      blk-mq tagging maintains a count of active users of a tag set.
      This allows us to maintain a notion of fairness between users,
      so that we can distribute the tag depth evenly without starving
      some users while allowing others to try unfair deep queues.
      
      If sharing of a tag set is detected, each hardware queue will
      track the depth of its own queue. And if this exceeds the total
      depth divided by the number of active queues, the user is actively
      throttled down.
      
      The active queue count is done lazily to avoid bouncing that data
      between submitter and completer. Each hardware queue gets marked
      active when it allocates its first tag, and gets marked inactive
      when 1) the last tag is cleared, and 2) the queue timeout grace
      period has passed.
      Signed-off-by: default avatarJens Axboe <[email protected]>
      0d2602ca
  21. 09 May, 2014 2 commits
    • Jens Axboe's avatar
      blk-mq: use sparser tag layout for lower queue depth · 59d13bf5
      Jens Axboe authored
      For best performance, spreading tags over multiple cachelines
      makes the tagging more efficient on multicore systems. But since
      we have 8 * sizeof(unsigned long) tags per cacheline, we don't
      always get a nice spread.
      
      Attempt to spread the tags over at least 4 cachelines, using fewer
      number of bits per unsigned long if we have to. This improves
      tagging performance in setups with 32-128 tags. For higher depths,
      the spread is the same as before (BITS_PER_LONG tags per cacheline).
      Signed-off-by: default avatarJens Axboe <[email protected]>
      59d13bf5
    • Jens Axboe's avatar
      blk-mq: implement new and more efficient tagging scheme · 4bb659b1
      Jens Axboe authored
      blk-mq currently uses percpu_ida for tag allocation. But that only
      works well if the ratio between tag space and number of CPUs is
      sufficiently high. For most devices and systems, that is not the
      case. The end result if that we either only utilize the tag space
      partially, or we end up attempting to fully exhaust it and run
      into lots of lock contention with stealing between CPUs. This is
      not optimal.
      
      This new tagging scheme is a hybrid bitmap allocator. It uses
      two tricks to both be SMP friendly and allow full exhaustion
      of the space:
      
      1) We cache the last allocated (or freed) tag on a per blk-mq
         software context basis. This allows us to limit the space
         we have to search. The key element here is not caching it
         in the shared tag structure, otherwise we end up dirtying
         more shared cache lines on each allocate/free operation.
      
      2) The tag space is split into cache line sized groups, and
         each context will start off randomly in that space. Even up
         to full utilization of the space, this divides the tag users
         efficiently into cache line groups, avoiding dirtying the same
         one both between allocators and between allocator and freeer.
      
      This scheme shows drastically better behaviour, both on small
      tag spaces but on large ones as well. It has been tested extensively
      to show better performance for all the cases blk-mq cares about.
      Signed-off-by: default avatarJens Axboe <[email protected]>
      4bb659b1
  22. 30 Apr, 2014 1 commit
    • Jens Axboe's avatar
      blk-mq: fix waiting for reserved tags · 5810d903
      Jens Axboe authored
      blk_mq_wait_for_tags() is only able to wait for "normal" tags,
      not reserved tags. Pass in which one we should attempt to get
      a tag for, so that waiting for reserved tags will work.
      
      Reserved tags are used for internal commands, which are usually
      serialized. Hence no waiting generally takes place, but we should
      ensure that it actually works if users need that functionality.
      Signed-off-by: default avatarJens Axboe <[email protected]>
      5810d903
  23. 15 Apr, 2014 1 commit
  24. 25 Oct, 2013 1 commit
    • Jens Axboe's avatar
      blk-mq: new multi-queue block IO queueing mechanism · 320ae51f
      Jens Axboe authored
      Linux currently has two models for block devices:
      
      - The classic request_fn based approach, where drivers use struct
        request units for IO. The block layer provides various helper
        functionalities to let drivers share code, things like tag
        management, timeout handling, queueing, etc.
      
      - The "stacked" approach, where a driver squeezes in between the
        block layer and IO submitter. Since this bypasses the IO stack,
        driver generally have to manage everything themselves.
      
      With drivers being written for new high IOPS devices, the classic
      request_fn based driver doesn't work well enough. The design dates
      back to when both SMP and high IOPS was rare. It has problems with
      scaling to bigger machines, and runs into scaling issues even on
      smaller machines when you have IOPS in the hundreds of thousands
      per device.
      
      The stacked approach is then most often selected as the model
      for the driver. But this means that everybody has to re-invent
      everything, and along with that we get all the problems again
      that the shared approach solved.
      
      This commit introduces blk-mq, block multi queue support. The
      design is centered around per-cpu queues for queueing IO, which
      then funnel down into x number of hardware submission queues.
      We might have a 1:1 mapping between the two, or it might be
      an N:M mapping. That all depends on what the hardware supports.
      
      blk-mq provides various helper functions, which include:
      
      - Scalable support for request tagging. Most devices need to
        be able to uniquely identify a request both in the driver and
        to the hardware. The tagging uses per-cpu caches for freed
        tags, to enable cache hot reuse.
      
      - Timeout handling without tracking request on a per-device
        basis. Basically the driver should be able to get a notification,
        if a request happens to fail.
      
      - Optional support for non 1:1 mappings between issue and
        submission queues. blk-mq can redirect IO completions to the
        desired location.
      
      - Support for per-request payloads. Drivers almost always need
        to associate a request structure with some driver private
        command structure. Drivers can tell blk-mq this at init time,
        and then any request handed to the driver will have the
        required size of memory associated with it.
      
      - Support for merging of IO, and plugging. The stacked model
        gets neither of these. Even for high IOPS devices, merging
        sequential IO reduces per-command overhead and thus
        increases bandwidth.
      
      For now, this is provided as a potential 3rd queueing model, with
      the hope being that, as it matures, it can replace both the classic
      and stacked model. That would get us back to having just 1 real
      model for block devices, leaving the stacked approach to dm/md
      devices (as it was originally intended).
      
      Contributions in this patch from the following people:
      
      Shaohua Li <[email protected]>
      Alexander Gordeev <[email protected]>
      Christoph Hellwig <[email protected]>
      Mike Christie <[email protected]>
      Matias Bjorling <[email protected]>
      Jeff Moyer <[email protected]>
      Acked-by: default avatarChristoph Hellwig <[email protected]>
      Signed-off-by: default avatarJens Axboe <[email protected]>
      320ae51f