22 Jul, 2016

6 commits

  • Coccinelle supports reading .cocciconfig, the order of precedence for
    variables for .cocciconfig is as follows:

    o Your current user's home directory is processed first
    o Your directory from which spatch is called is processed next
    o The directory provided with the --dir option is processed last, if used

    Since coccicheck runs through make, it naturally runs from the kernel
    proper dir, as such the second rule above would be implied for picking up a
    .cocciconfig when using 'make coccicheck'.

    'make coccicheck' also supports using M= targets.If you do not supply
    any M= target, it is assumed you want to target the entire kernel.
    The kernel coccicheck script has:

    if [ "$KBUILD_EXTMOD" = "" ] ; then
    OPTIONS="--dir $srctree $COCCIINCLUDE"
    else
    OPTIONS="--dir $KBUILD_EXTMOD $COCCIINCLUDE"
    fi

    KBUILD_EXTMOD is set when an explicit target with M= is used. For both cases
    the spatch --dir argument is used, as such third rule applies when
    whether M= is used or not, and when M= is used the target directory can
    have its own .cocciconfig file. When M= is not passed as an argument to
    coccicheck the target directory is the same as the directory from where
    spatch was called.

    If not using the kernel's coccicheck target, keep the above precedence order
    logic of .cocciconfig reading. If using the kernel's coccicheck target,
    override any of the kernel's .coccicheck's settings using SPFLAGS.

    We help Coccinelle when used against Linux with a set of sensible defaults
    options for Linux with our own Linux .cocciconfig. This hints to coccinelle
    git can be used for 'git grep' queries over coccigrep. A timeout of 200
    seconds should suffice for now.

    The options picked up by coccinelle when reading a .cocciconfig do not appear
    as arguments to spatch processes running on your system, to confirm what
    options will be used by Coccinelle run:

    spatch --print-options-only

    You can override with your own preferred index option by using SPFLAGS.
    Coccinelle supports both glimpse and idutils. Glimpse had historically
    provided the best performance, however recent benchmarks reveal idutils
    is performing just as well. Due to some recent fixes however you however
    will need at least coccinelle >= 1.0.6 if using idutils.

    Coccinelle carries a script scripts/idutils_index.sh which creates the
    idutils database with as follows:

    mkid -i C --output .id-utils.index

    If using just "--use-idutils" coccinelle expects your idutils database to be
    on the top level of the kernel as a file named ".id-utils.index". If you do
    not use this you can symlink your database file to it, or you can specify the
    database file following the "--use-idutils" argument. Examples:

    make SPFLAGS=--use-idutils coccicheck

    This assumes you have $srctree/.id-utils.index, where $srctree is
    the top level of the kernel.

    make SPFLAGS="--use-idutils /full-path/to/ID" coccicheck

    Here you specify the full path of the idutils ID database. Using
    .cocciconfig is possible, however given the order of precedence followed
    by Coccinelle, and since the kernel now carries its own .cocciconfig,
    you will need to use SPFLAGS to use idutils if desired.

    v4:

    o Recommend upgrade for using idutils with coccinelle due to some
    recent fixes.

    o Refer to using --print-options-only for testing what options are
    picked up by .cocciconfig reading.

    o Expand commit log considerably explaining *why* .cocconfig from
    two precedence rules are used when using coccicheck, and how to
    properly override these if needed.

    o Expand Documentation/coccinelle.txt

    v3: Expand commit log a bit more

    Signed-off-by: Luis R. Rodriguez
    Acked-by: Julia Lawall
    Signed-off-by: Michal Marek

    Luis R. Rodriguez
     
  • When debugging (using --profile or --show-trying) you want to
    avoid supressing output, use --quiet instead. While at it, extend
    documentation for SPFLAGS use.

    For instance one can use:

    $ export COCCI=scripts/coccinelle/misc/irqf_oneshot.cocci
    $ make coccicheck DEBUG_FILE="poo.err" MODE=report SPFLAGS="--profile --show-trying" M=./drivers/mfd/arizona-irq.c

    Expand Documentation/coccinelle.txt as well.

    v4: expand Documentation/coccinelle.txt
    v3: rebased, resolve conflicts, expand Documentation/coccinelle.txt
    v2: use egrep instead of the *"=--option"* check, this doesn't work for
    disjunctions.

    Signed-off-by: Luis R. Rodriguez
    Acked-by: Julia Lawall
    Signed-off-by: Michal Marek

    Luis R. Rodriguez
     
  • Enable to capture stderr via a DEBUG_FILE variable passed to
    coccicheck. You can now do:

    $ rm -f cocci.err
    $ export COCCI=scripts/coccinelle/free/kfree.cocci
    $ make coccicheck MODE=report DEBUG_FILE=cocci.err
    ...
    $ cat cocci.err

    This will be come more useful once we add support to
    use more things which would go into stderr, such as
    profiling. That will be done separately in another
    commit.

    Expand Documentation/coccinelle.txt with details.

    Signed-off-by: Luis R. Rodriguez
    Acked-by: Nicolas Palix
    Signed-off-by: Michal Marek

    Luis R. Rodriguez
     
  • Coccinelle has had parmap support since 1.0.2, this means
    it supports --jobs, enabling built-in multithreaded functionality,
    instead of needing one to script it out. Just look for --jobs
    in the help output to determine if this is supported and use it
    only if your number of processors detected is > 1.

    If parmap is enabled also enable the load balancing to be dynamic, so
    that if a thread finishes early we keep feeding it.

    stderr is currently sent to /dev/null, addressing a way to capture
    that will be addressed next.

    If --jobs is not supported we fallback to the old mechanism.
    We expect to deprecate the old mechanism as soon as we can get
    confirmation all users are ready.

    While at it propagate back into the shell script any coccinelle error
    code. When used in serialized mode where all cocci files are run this
    also stops processing if an error has occured. This lets us handle some
    errors in coccinelle cocci files and if they bail out we should inspect
    the errors. This will be more useful later to help annotate coccinelle
    version dependency requirements. This will let you run only SmPL files
    that your system supports.

    Extend Documentation/coccinelle.txt as well.

    As a small example, prior to this change, on an 8-core system:

    Before:

    $ export COCCI=scripts/coccinelle/free/kfree.cocci
    $ time make coccicheck MODE=report
    ...

    real 29m14.912s
    user 103m1.796s
    sys 0m4.464s

    After:

    real 16m22.435s
    user 128m30.060s
    sys 0m2.712s

    v4:

    o expand Documentation/coccinelle.txt to reflect parmap support info
    o update commit log to reflect what we actually do now with stderr
    o split out DEBUG_FILE use into another patch
    o detect number of CPUs and if its 1 then skip parmap support,
    note that if you still support parmap, but have 1 CPU you will
    also go through the new branches, so the old complex multithreaded process
    is skipped as well.

    v3:

    o move USE_JOBS to avoid being overriden

    v2:

    o redirect coccinelle stderr to /dev/null by default and
    only if DEBUG_FILE is used do we pass it to a file
    o fix typo of paramap/parmap

    Signed-off-by: Luis R. Rodriguez
    Acked-by: Nicolas Palix
    Signed-off-by: Michal Marek

    Luis R. Rodriguez
     
  • SPFLAGS is set early, it means that any heuristics done on
    coccicheck cannot be overridden currently. Move SPFLAGS
    after OPTIONS and set this at the end. This lets you override
    any heuristics as coccinelle treats conflicts by only listening
    to the last option that makes sense.

    v3: this patch was added in the v3 series
    v4: Update Documentation/coccinelle.txt explaining how
    SPFLAGS works as well.

    Signed-off-by: Luis R. Rodriguez
    Acked-by: Nicolas Palix
    Signed-off-by: Michal Marek

    Luis R. Rodriguez
     
  • This has no functional changes. This is being done
    to enable us to later use spatch binary for some
    flag checking for certain features early on.

    Signed-off-by: Luis R. Rodriguez
    Acked-by: Nicolas Palix
    Signed-off-by: Michal Marek

    Luis R. Rodriguez
     

19 Jul, 2016

1 commit

  • On May 4th, Bjørn Mork provided patch 697bbc7b8320 ("builddeb: include
    objtool binary in headers package"). However, that one only works if
    $srctree=$objtree, because the objtool binaries are not written to the
    srctree, but to the objtree.

    Signed-off-by: Wilfried Klaebe
    Fixes: 697bbc7b8320 ("builddeb: include objtool binary in headers package")
    Signed-off-by: Michal Marek

    Wilfried Klaebe
     

21 Jun, 2016

4 commits

  • krealloc() must not be used against devm_*() allocated
    memory regions:

    - if a bigger memory is to be allocated, krealloc() and
    __krealloc() could return a different pointer than the
    one given to them, creating a memory region which is not
    managed, thus it will not be automatically released on
    device removal.

    - if a bigger memory is to be allocated, krealloc() could
    kfree() the managed memory region which is passed to it.
    The old pointer is left registered as a resource for the
    device. On device removal, this dangling pointer will be
    used and an unrelated memory region could be released.

    - if the requested size is equal to 0, krealloc() can also
    just behave like kfree(). Here too, the old pointer is
    kept associated with the device. On device removal, this
    invalid pointer will be used and an unrelated memory
    region could be released.

    For all these reasons, krealloc() must not be used on a
    pointer returned by devm_*() functions.

    Cc: Tejun Heo
    Cc: Pekka Enberg
    Acked-by: Julia Lawall
    Signed-off-by: Yann Droneaud
    Signed-off-by: Michal Marek

    Yann Droneaud
     
  • Updates free/devm_free.cocci to recognize functions added by:

    - commit 64c862a839a8 ('devres: add kernel standard devm_k.alloc functions')
    - commit e31108cad3de ('devres: introduce API "devm_kstrdup"')
    - commit 3046365bb470 ('devres: introduce API "devm_kmemdup')
    - commit 43339bed7010 ('devres: Add devm_get_free_pages API')
    - commit 75f2a4ead5d5 ('devres: Add devm_kasprintf and devm_kvasprintf API')

    See also Documentation/driver-model/devres.txt

    Cc: Joe Perches
    Cc: Manish Badarkhe
    Cc: Srinivas Pandruvada
    Cc: Eli Billauer
    Cc: Himangi Saraogi
    Cc: Geert Uytterhoeven
    Cc: Wolfram Sang
    Cc: Daniel Thompson
    Acked-by: Julia Lawall
    Signed-off-by: Yann Droneaud
    Signed-off-by: Michal Marek

    Yann Droneaud
     
  • Since commit 3ef0e5ba4673 ('slab: introduce kzfree()'),
    kfree() is no more the only function to be considered:
    kzfree() should be recognized too.

    In particular, kzfree() must not be called on memory
    allocated through devm_*() functions.

    Cc: Johannes Weiner
    Acked-by: Julia Lawall
    Signed-off-by: Yann Droneaud
    Signed-off-by: Michal Marek

    Yann Droneaud
     
  • Documentation/coccinelle.txt suggests using the SPFLAGS
    make variable to pass additional options to spatch.

    Reorder the way SPFLAGS is added to FLAGS, to allow
    for options in the SPFLAGS to override the default
    --very-quiet option.

    Similarly, rearrage the FLAGS for org or report mode.
    This allows for overriding of the default --no-show-diff
    option through SPFLAGS.

    Signed-off-by: Deepa Dinamani
    Cc: Gilles Muller
    Acked-by: Nicolas Palix
    Acked-by: Julia Lawall
    Signed-off-by: Michal Marek

    Deepa Dinamani
     

20 Jun, 2016

1 commit


30 May, 2016

1 commit


29 May, 2016

23 commits

  • The self-test was updated to cover zero-length strings; the function
    needs to be updated, too.

    Reported-by: Geert Uytterhoeven
    Signed-off-by: George Spelvin
    Fixes: fcfd2fbf22d2 ("fs/namei.c: Add hashlen_string() function")
    Signed-off-by: Linus Torvalds

    George Spelvin
     
  • The original name was simply hash_string(), but that conflicted with a
    function with that name in drivers/base/power/trace.c, and I decided
    that calling it "hashlen_" was better anyway.

    But you have to do it in two places.

    [ This caused build errors for architectures that don't define
    CONFIG_DCACHE_WORD_ACCESS - Linus ]

    Signed-off-by: George Spelvin
    Reported-by: Guenter Roeck
    Fixes: fcfd2fbf22d2 ("fs/namei.c: Add hashlen_string() function")
    Signed-off-by: Linus Torvalds

    George Spelvin
     
  • The HPFS filesystem used generic_show_options to produce string that is
    displayed in /proc/mounts. However, there is a problem that the options
    may disappear after remount. If we mount the filesystem with option1
    and then remount it with option2, /proc/mounts should show both option1
    and option2, however it only shows option2 because the whole option
    string is replaced with replace_mount_options in hpfs_remount_fs.

    To fix this bug, implement the hpfs_show_options function that prints
    options that are currently selected.

    Signed-off-by: Mikulas Patocka
    Cc: stable@vger.kernel.org
    Signed-off-by: Linus Torvalds

    Mikulas Patocka
     
  • Commit c8f33d0bec99 ("affs: kstrdup() memory handling") checks if the
    kstrdup function returns NULL due to out-of-memory condition.

    However, if we are remounting a filesystem with no change to
    filesystem-specific options, the parameter data is NULL. In this case,
    kstrdup returns NULL (because it was passed NULL parameter), although no
    out of memory condition exists. The mount syscall then fails with
    ENOMEM.

    This patch fixes the bug. We fail with ENOMEM only if data is non-NULL.

    The patch also changes the call to replace_mount_options - if we didn't
    pass any filesystem-specific options, we don't call
    replace_mount_options (thus we don't erase existing reported options).

    Fixes: c8f33d0bec99 ("affs: kstrdup() memory handling")
    Signed-off-by: Mikulas Patocka
    Cc: stable@vger.kernel.org # v4.1+
    Signed-off-by: Linus Torvalds

    Mikulas Patocka
     
  • Commit ce657611baf9 ("hpfs: kstrdup() out of memory handling") checks if
    the kstrdup function returns NULL due to out-of-memory condition.

    However, if we are remounting a filesystem with no change to
    filesystem-specific options, the parameter data is NULL. In this case,
    kstrdup returns NULL (because it was passed NULL parameter), although no
    out of memory condition exists. The mount syscall then fails with
    ENOMEM.

    This patch fixes the bug. We fail with ENOMEM only if data is non-NULL.

    The patch also changes the call to replace_mount_options - if we didn't
    pass any filesystem-specific options, we don't call
    replace_mount_options (thus we don't erase existing reported options).

    Fixes: ce657611baf9 ("hpfs: kstrdup() out of memory handling")
    Signed-off-by: Mikulas Patocka
    Cc: stable@vger.kernel.org
    Signed-off-by: Linus Torvalds

    Mikulas Patocka
     
  • Pull more MIPS updates from Ralf Baechle:
    "This is the secondnd batch of MIPS patches for 4.7. Summary:

    CPS:
    - Copy EVA configuration when starting secondary VPs.

    EIC:
    - Clear Status IPL.

    Lasat:
    - Fix a few off by one bugs.

    lib:
    - Mark intrinsics notrace. Not only are the intrinsics
    uninteresting, it would cause infinite recursion.

    MAINTAINERS:
    - Add file patterns for MIPS BRCM device tree bindings.
    - Add file patterns for mips device tree bindings.

    MT7628:
    - Fix MT7628 pinmux typos.
    - wled_an pinmux gpio.
    - EPHY LEDs pinmux support.

    Pistachio:
    - Enable KASLR

    VDSO:
    - Build microMIPS VDSO for microMIPS kernels.
    - Fix aliasing warning by building with `-fno-strict-aliasing' for
    debugging but also tracing them might result in recursion.

    Misc:
    - Add missing FROZEN hotplug notifier transitions.
    - Fix clk binding example for varioius PIC32 devices.
    - Fix cpu interrupt controller node-names in the DT files.
    - Fix XPA CPU feature separation.
    - Fix write_gc0_* macros when writing zero.
    - Add inline asm encoding helpers.
    - Add missing VZ accessor microMIPS encodings.
    - Fix little endian microMIPS MSA encodings.
    - Add 64-bit HTW fields and fix its configuration.
    - Fix sigreturn via VDSO on microMIPS kernel.
    - Lots of typo fixes.
    - Add definitions of SegCtl registers and use them"

    * 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus: (49 commits)
    MIPS: Add missing FROZEN hotplug notifier transitions
    MIPS: Build microMIPS VDSO for microMIPS kernels
    MIPS: Fix sigreturn via VDSO on microMIPS kernel
    MIPS: devicetree: fix cpu interrupt controller node-names
    MIPS: VDSO: Build with `-fno-strict-aliasing'
    MIPS: Pistachio: Enable KASLR
    MIPS: lib: Mark intrinsics notrace
    MIPS: Fix 64-bit HTW configuration
    MIPS: Add 64-bit HTW fields
    MAINTAINERS: Add file patterns for mips device tree bindings
    MAINTAINERS: Add file patterns for mips brcm device tree bindings
    MIPS: Simplify DSP instruction encoding macros
    MIPS: Add missing tlbinvf/XPA microMIPS encodings
    MIPS: Fix little endian microMIPS MSA encodings
    MIPS: Add missing VZ accessor microMIPS encodings
    MIPS: Add inline asm encoding helpers
    MIPS: Spelling fix lets -> let's
    MIPS: VR41xx: Fix typo
    MIPS: oprofile: Fix typo
    MIPS: math-emu: Fix typo
    ...

    Linus Torvalds
     
  • Various builds (such as i386:allmodconfig) fail with

    fs/binfmt_aout.c:133:2: error: expected identifier or '(' before 'return'
    fs/binfmt_aout.c:134:1: error: expected identifier or '(' before '}' token

    [ Oops. My bad, I had stupidly thought that "allmodconfig" covered this
    on x86-64 too, but it obviously doesn't. Egg on my face. - Linus ]

    Fixes: 5d22fc25d4fc ("mm: remove more IS_ERR_VALUE abuses")
    Signed-off-by: Guenter Roeck
    Signed-off-by: Linus Torvalds

    Guenter Roeck
     
  • Pull string hash improvements from George Spelvin:
    "This series does several related things:

    - Makes the dcache hash (fs/namei.c) useful for general kernel use.

    (Thanks to Bruce for noticing the zero-length corner case)

    - Converts the string hashes in to use the
    above.

    - Avoids 64-bit multiplies in hash_64() on 32-bit platforms. Two
    32-bit multiplies will do well enough.

    - Rids the world of the bad hash multipliers in hash_32.

    This finishes the job started in commit 689de1d6ca95 ("Minimal
    fix-up of bad hashing behavior of hash_64()")

    The vast majority of Linux architectures have hardware support for
    32x32-bit multiply and so derive no benefit from "simplified"
    multipliers.

    The few processors that do not (68000, h8/300 and some models of
    Microblaze) have arch-specific implementations added. Those
    patches are last in the series.

    - Overhauls the dcache hash mixing.

    The patch in commit 0fed3ac866ea ("namei: Improve hash mixing if
    CONFIG_DCACHE_WORD_ACCESS") was an off-the-cuff suggestion.
    Replaced with a much more careful design that's simultaneously
    faster and better. (My own invention, as there was noting suitable
    in the literature I could find. Comments welcome!)

    - Modify the hash_name() loop to skip the initial HASH_MIX(). This
    would let us salt the hash if we ever wanted to.

    - Sort out partial_name_hash().

    The hash function is declared as using a long state, even though
    it's truncated to 32 bits at the end and the extra internal state
    contributes nothing to the result. And some callers do odd things:

    - fs/hfs/string.c only allocates 32 bits of state
    - fs/hfsplus/unicode.c uses it to hash 16-bit unicode symbols not bytes

    - Modify bytemask_from_count to handle inputs of 1..sizeof(long)
    rather than 0..sizeof(long)-1. This would simplify users other
    than full_name_hash"

    Special thanks to Bruce Fields for testing and finding bugs in v1. (I
    learned some humbling lessons about "obviously correct" code.)

    On the arch-specific front, the m68k assembly has been tested in a
    standalone test harness, I've been in contact with the Microblaze
    maintainers who mostly don't care, as the hardware multiplier is never
    omitted in real-world applications, and I haven't heard anything from
    the H8/300 world"

    * 'hash' of git://ftp.sciencehorizons.net/linux:
    h8300: Add
    microblaze: Add
    m68k: Add
    : Add support for architecture-specific functions
    fs/namei.c: Improve dcache hash function
    Eliminate bad hash multipliers from hash_32() and hash_64()
    Change hash_64() return value to 32 bits
    : Define hash_str() in terms of hashlen_string()
    fs/namei.c: Add hashlen_string() function
    Pull out string hash to

    Linus Torvalds
     
  • This will improve the performance of hash_32() and hash_64(), but due
    to complete lack of multi-bit shift instructions on H8, performance will
    still be bad in surrounding code.

    Designing H8-specific hash algorithms to work around that is a separate
    project. (But if the maintainers would like to get in touch...)

    Signed-off-by: George Spelvin
    Cc: Yoshinori Sato
    Cc: uclinux-h8-devel@lists.sourceforge.jp

    George Spelvin
     
  • Microblaze is an FPGA soft core that can be configured various ways.

    If it is configured without a multiplier, the standard __hash_32()
    will require a call to __mulsi3, which is a slow software loop.

    Instead, use a shift-and-add sequence for the constant multiply.
    GCC knows how to do this, but it's not as clever as some.

    Signed-off-by: George Spelvin
    Cc: Alistair Francis
    Cc: Michal Simek

    George Spelvin
     
  • This provides a multiply by constant GOLDEN_RATIO_32 = 0x61C88647
    for the original mc68000, which lacks a 32x32-bit multiply instruction.

    Yes, the amount of optimization effort put in is excessive. :-)

    Shift-add chain found by Yevgen Voronenko's Hcub algorithm at
    http://spiral.ece.cmu.edu/mcm/gen.html

    Signed-off-by: George Spelvin
    Cc: Geert Uytterhoeven
    Cc: Greg Ungerer
    Cc: Andreas Schwab
    Cc: Philippe De Muyter
    Cc: linux-m68k@lists.linux-m68k.org

    George Spelvin
     
  • This is just the infrastructure; there are no users yet.

    This is modelled on CONFIG_ARCH_RANDOM; a CONFIG_ symbol declares
    the existence of .

    That file may define its own versions of various functions, and define
    HAVE_* symbols (no CONFIG_ prefix!) to suppress the generic ones.

    Included is a self-test (in lib/test_hash.c) that verifies the basics.
    It is NOT in general required that the arch-specific functions compute
    the same thing as the generic, but if a HAVE_* symbol is defined with
    the value 1, then equality is tested.

    Signed-off-by: George Spelvin
    Cc: Geert Uytterhoeven
    Cc: Greg Ungerer
    Cc: Andreas Schwab
    Cc: Philippe De Muyter
    Cc: linux-m68k@lists.linux-m68k.org
    Cc: Alistair Francis
    Cc: Michal Simek
    Cc: Yoshinori Sato
    Cc: uclinux-h8-devel@lists.sourceforge.jp

    George Spelvin
     
  • Patch 0fed3ac866 improved the hash mixing, but the function is slower
    than necessary; there's a 7-instruction dependency chain (10 on x86)
    each loop iteration.

    Word-at-a-time access is a very tight loop (which is good, because
    link_path_walk() is one of the hottest code paths in the entire kernel),
    and the hash mixing function must not have a longer latency to avoid
    slowing it down.

    There do not appear to be any published fast hash functions that:
    1) Operate on the input a word at a time, and
    2) Don't need to know the length of the input beforehand, and
    3) Have a single iterated mixing function, not needing conditional
    branches or unrolling to distinguish different loop iterations.

    One of the algorithms which comes closest is Yann Collet's xxHash, but
    that's two dependent multiplies per word, which is too much.

    The key insights in this design are:

    1) Barring expensive ops like multiplies, to diffuse one input bit
    across 64 bits of hash state takes at least log2(64) = 6 sequentially
    dependent instructions. That is more cycles than we'd like.
    2) An operation like "hash ^= hash << 13" requires a second temporary
    register anyway, and on a 2-operand machine like x86, it's three
    instructions.
    3) A better use of a second register is to hold a two-word hash state.
    With careful design, no temporaries are needed at all, so it doesn't
    increase register pressure. And this gets rid of register copying
    on 2-operand machines, so the code is smaller and faster.
    4) Using two words of state weakens the requirement for one-round mixing;
    we now have two rounds of mixing before cancellation is possible.
    5) A two-word hash state also allows operations on both halves to be
    done in parallel, so on a superscalar processor we get more mixing
    in fewer cycles.

    I ended up using a mixing function inspired by the ChaCha and Speck
    round functions. It is 6 simple instructions and 3 cycles per iteration
    (assuming multiply by 9 can be done by an "lea" instruction):

    x ^= *input++;
    y ^= x; x = ROL(x, K1);
    x += y; y = ROL(y, K2);
    y *= 9;

    Not only is this reversible, two consecutive rounds are reversible:
    if you are given the initial and final states, but not the intermediate
    state, it is possible to compute both input words. This means that at
    least 3 words of input are required to create a collision.

    (It also has the property, used by hash_name() to avoid a branch, that
    it hashes all-zero to all-zero.)

    The rotate constants K1 and K2 were found by experiment. The search took
    a sample of random initial states (I used 1023) and considered the effect
    of flipping each of the 64 input bits on each of the 128 output bits two
    rounds later. Each of the 8192 pairs can be considered a biased coin, and
    adding up the Shannon entropy of all of them produces a score.

    The best-scoring shifts also did well in other tests (flipping bits in y,
    trying 3 or 4 rounds of mixing, flipping all 64*63/2 pairs of input bits),
    so the choice was made with the additional constraint that the sum of the
    shifts is odd and not too close to the word size.

    The final state is then folded into a 32-bit hash value by a less carefully
    optimized multiply-based scheme. This also has to be fast, as pathname
    components tend to be short (the most common case is one iteration!), but
    there's some room for latency, as there is a fair bit of intervening logic
    before the hash value is used for anything.

    (Performance verified with "bonnie++ -s 0 -n 1536:-2" on tmpfs. I need
    a better benchmark; the numbers seem to show a slight dip in performance
    between 4.6.0 and this patch, but they're too noisy to quote.)

    Special thanks to Bruce fields for diligent testing which uncovered a
    nasty fencepost error in an earlier version of this patch.

    [checkpatch.pl formatting complaints noted and respectfully disagreed with.]

    Signed-off-by: George Spelvin
    Tested-by: J. Bruce Fields

    George Spelvin
     
  • The "simplified" prime multipliers made very bad hash functions, so get rid
    of them. This completes the work of 689de1d6ca.

    To avoid the inefficiency which was the motivation for the "simplified"
    multipliers, hash_64() on 32-bit systems is changed to use a different
    algorithm. It makes two calls to hash_32() instead.

    drivers/media/usb/dvb-usb-v2/af9015.c uses the old GOLDEN_RATIO_PRIME_32
    for some horrible reason, so it inherits a copy of the old definition.

    Signed-off-by: George Spelvin
    Cc: Antti Palosaari
    Cc: Mauro Carvalho Chehab

    George Spelvin
     
  • That's all that's ever asked for, and it makes the return
    type of hash_long() consistent.

    It also allows (upcoming patch) an optimized implementation
    of hash_64 on 32-bit machines.

    I tried adding a BUILD_BUG_ON to ensure the number of bits requested
    was never more than 32 (most callers use a compile-time constant), but
    adding to breaks the tools/perf compiler
    unless tools/perf/MANIFEST is updated, and understanding that code base
    well enough to update it is too much trouble. I did the rest of an
    allyesconfig build with such a check, and nothing tripped.

    Signed-off-by: George Spelvin

    George Spelvin
     
  • Finally, the first use of previous two patches: eliminate the
    separate ad-hoc string hash functions in the sunrpc code.

    Now hash_str() is a wrapper around hash_string(), and hash_mem() is
    likewise a wrapper around full_name_hash().

    Note that sunrpc code *does* call hash_mem() with a zero length, which
    is why the previous patch needed to handle that in full_name_hash().
    (Thanks, Bruce, for finding that!)

    This also eliminates the only caller of hash_long which asks for
    more than 32 bits of output.

    The comment about the quality of hashlen_string() and full_name_hash()
    is jumping the gun by a few patches; they aren't very impressive now,
    but will be improved greatly later in the series.

    Signed-off-by: George Spelvin
    Tested-by: J. Bruce Fields
    Acked-by: J. Bruce Fields
    Cc: Jeff Layton
    Cc: linux-nfs@vger.kernel.org

    George Spelvin
     
  • We'd like to make more use of the highly-optimized dcache hash functions
    throughout the kernel, rather than have every subsystem create its own,
    and a function that hashes basic null-terminated strings is required
    for that.

    (The name is to emphasize that it returns both hash and length.)

    It's actually useful in the dcache itself, specifically d_alloc_name().
    Other uses in the next patch.

    full_name_hash() is also tweaked to make it more generally useful:
    1) Take a "char *" rather than "unsigned char *" argument, to
    be consistent with hash_name().
    2) Handle zero-length inputs. If we want more callers, we don't want
    to make them worry about corner cases.

    Signed-off-by: George Spelvin

    George Spelvin
     
  • ... so they can be used without the rest of

    The hashlen_* macros will make sense next patch.

    Signed-off-by: George Spelvin

    George Spelvin
     
  • Pull i2c fix from Wolfram Sang:
    "A fix for a regression introduced yesterday.

    The regression didn't show up here locally because I did not have
    PAGE_POISONING enabled. And buildbots discovered this only after it
    hit your tree. Thanks to Dan for the quick response"

    * 'i2c/for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
    i2c: dev: use after free in detach

    Linus Torvalds
     
  • Pull chrome platform updates from Olof Johansson
    "A handful of Chrome driver and binding changes this merge window:

    - a few patches to fix probing and configuration of pstore

    - a few patches adding Elan touchpad registration on a few devices

    - EC changes: a security fix dealing with max message sizes and
    addition of compat_ioctl support.

    - keyboard backlight control support

    There was also an accidential duplicate registration of trackpads on
    'Leon', which was reverted just recently"

    * tag 'chrome-platform' of git://git.kernel.org/pub/scm/linux/kernel/git/olof/chrome-platform:
    Revert "platform/chrome: chromeos_laptop: Add Leon Touch"
    platform/chrome: chromeos_laptop - Add Elan touchpad for Wolf
    platform/chrome: chromeos_laptop - Add elan trackpad option for C720
    platform/chrome: cros_ec_dev - Populate compat_ioctl
    platform/chrome: cros_ec_lightbar - use name instead of ID to hide lightbar attributes
    platform/chrome: cros_ec_dev - Fix security issue
    platform/chrome: Add Chrome OS keyboard backlight LEDs support
    platform/chrome: use to_platform_device()
    platform/chrome: pstore: Move to larger record size.
    platform/chrome: pstore: probe for ramoops buffer using acpi
    platform/chrome: chromeos_laptop: Add Leon Touch

    Linus Torvalds
     
  • Pull more sound updates from Takashi Iwai:
    "This is the second update round for 4.7-rc1. Most of changes are
    about the pending ASoC updates and fixes, including a few new drivers.
    Below are some highlights:

    ASoC:
    - New drivers for MAX98371 and TAS5720
    - SPI support for TLV320AIC32x4, along with the module split
    - TDM support for STI Uniperf IPs
    - Remaining topology API fixes / updates

    HDA:
    - A couple of Dell quirks and new Realtek codec support"

    * tag 'sound-4.7-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound: (63 commits)
    ALSA: hda - Fix headset mic detection problem for one Dell machine
    spi: spi-ep93xx: Fix the PTR_ERR() argument
    ALSA: hda/realtek - Add support for ALC295/ALC3254
    ASoC: kirkwood: fix build failure
    ALSA: hda - Fix headphone noise on Dell XPS 13 9360
    ASoC: ak4642: Enable cache usage to fix crashes on resume
    ASoC: twl6040: Disconnect AUX output pads on digital mute
    ASoC: tlv320aic32x4: Properly implement the positive and negative pins into the mixers
    rcar: src: skip disabled-SRC nodes
    ASoC: max98371 Remove duplicate entry in max98371_reg
    ASoC: twl6040: Select LPPLL during standby
    ASoC: rsnd: don't use prohibited number to PDMACHCRn.SRS
    ASoC: simple-card: Add pm callbacks to platform driver
    ASoC: pxa: Fix module autoload for platform drivers
    ASoC: topology: Fix memory leak in widget creation
    ASoC: Add max98371 codec driver
    ASoC: rsnd: count .probe/.remove for rsnd_mod_call()
    ASoC: topology: Check size mismatch of ABI objects before parsing
    ASoC: topology: Check failure to create a widget
    ASoC: add support for TAS5720 digital amplifier
    ...

    Linus Torvalds
     
  • Pull SCSI target updates from Nicholas Bellinger:
    "Here are the outstanding target pending updates for v4.7-rc1.

    The highlights this round include:

    - Allow external PR/ALUA metadata path be defined at runtime via top
    level configfs attribute (Lee)
    - Fix target session shutdown bug for ib_srpt multi-channel (hch)
    - Make TFO close_session() and shutdown_session() optional (hch)
    - Drop se_sess->sess_kref + convert tcm_qla2xxx to internal kref
    (hch)
    - Add tcm_qla2xxx endpoint attribute for basic FC jammer (Laurence)
    - Refactor iscsi-target RX/TX PDU encode/decode into common code
    (Varun)
    - Extend iscsit_transport with xmit_pdu, release_cmd, get_rx_pdu,
    validate_parameters, and get_r2t_ttt for generic ISO offload
    (Varun)
    - Initial merge of cxgb iscsi-segment offload target driver (Varun)

    The bulk of the changes are Chelsio's new driver, along with a number
    of iscsi-target common code improvements made by Varun + Co along the
    way"

    * 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending: (29 commits)
    iscsi-target: Fix early sk_data_ready LOGIN_FLAGS_READY race
    cxgbit: Use type ISCSI_CXGBIT + cxgbit tpg_np attribute
    iscsi-target: Convert transport drivers to signal rdma_shutdown
    iscsi-target: Make iscsi_tpg_np driver show/store use generic code
    tcm_qla2xxx Add SCSI command jammer/discard capability
    iscsi-target: graceful disconnect on invalid mapping to iovec
    target: need_to_release is always false, remove redundant check and kfree
    target: remove sess_kref and ->shutdown_session
    iscsi-target: remove usage of ->shutdown_session
    tcm_qla2xxx: introduce a private sess_kref
    target: make close_session optional
    target: make ->shutdown_session optional
    target: remove acl_stop
    target: consolidate and fix session shutdown
    cxgbit: add files for cxgbit.ko
    iscsi-target: export symbols
    iscsi-target: call complete on conn_logout_comp
    iscsi-target: clear tx_thread_active
    iscsi-target: add new offload transport type
    iscsi-target: use conn_transport->transport_type in text rsp
    ...

    Linus Torvalds
     
  • Pull more rdma updates from Doug Ledford:
    "This is the second group of code for the 4.7 merge window. It looks
    large, but only in one sense. I'll get to that in a minute. The list
    of changes here breaks down as follows:

    - Dynamic counter infrastructure in the IB drivers

    This is a sysfs based code to allow free form access to the
    hardware counters RDMA devices might support so drivers don't need
    to code this up repeatedly themselves

    - SendOnlyFullMember multicast support

    - IB router support

    - A couple misc fixes

    - The big item on the list: hfi1 driver updates, plus moving the hfi1
    driver out of staging

    There was a group of 15 patches in the hfi1 list that I thought I had
    in the first pull request but they weren't. So that added to the
    length of the hfi1 section here.

    As far as these go, everything but the hfi1 is pretty straight
    forward.

    The hfi1 is, if you recall, the driver that Al had complaints about
    how it used the write/writev interfaces in an overloaded fashion. The
    write portion of their interface behaved like the write handler in the
    IB stack proper and did bi-directional communications. The writev
    interface, on the other hand, only accepts SDMA request structures.
    The completions for those structures are sent back via an entirely
    different event mechanism.

    With the security patch, we put security checks on the write
    interface, however, we also knew they would be going away soon. Now,
    we've converted the write handler in the hfi1 driver to use ioctls
    from the IB reserved magic area for its bidirectional communications.
    With that change, Intel has addressed all of the items originally on
    their TODO when they went into staging (as well as many items added to
    the list later).

    As such, I moved them out, and since they were the last item in the
    staging/rdma directory, and I don't have immediate plans to use the
    staging area again, I removed the staging/rdma area.

    Because of the move out of staging, as well as a series of 5 patches
    in the hfi1 driver that removed code people thought should be done in
    a different way and was optional to begin with (a snoop debug
    interface, an eeprom driver for an eeprom connected directory to their
    hfi1 chip and not via an i2c bus, and a few other things like that),
    the line count, especially the removal count, is high"

    * tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dledford/rdma: (56 commits)
    staging/rdma: Remove the entire rdma subdirectory of staging
    IB/core: Make device counter infrastructure dynamic
    IB/hfi1: Fix pio map initialization
    IB/hfi1: Correct 8051 link parameter settings
    IB/hfi1: Update pkey table properly after link down or FM start
    IB/rdamvt: Fix rdmavt s_ack_queue sizing
    IB/rdmavt: Max atomic value should be a u8
    IB/hfi1: Fix hard lockup due to not using save/restore spin lock
    IB/hfi1: Add tracing support for send with invalidate opcode
    IB/hfi1, qib: Add ieth to the packet header definitions
    IB/hfi1: Move driver out of staging
    IB/hfi1: Do not free hfi1 cdev parent structure early
    IB/hfi1: Add trace message in user IOCTL handling
    IB/hfi1: Remove write(), use ioctl() for user cmds
    IB/hfi1: Add ioctl() interface for user commands
    IB/hfi1: Remove unused user command
    IB/hfi1: Remove snoop/diag interface
    IB/hfi1: Remove EPROM functionality from data device
    IB/hfi1: Remove UI char device
    IB/hfi1: Remove multiple device cdev
    ...

    Linus Torvalds
     

28 May, 2016

4 commits

  • This reverts commit bff3c624dc7261a084a4d25a0b09c3fb0fec872a.

    Board "Leon" is otherwise known as "Toshiba CB35" and we already have
    the entry that supports that board as of this commit :
    963cb6f platform/chrome: chromeos_laptop - Add Toshiba CB35 Touch

    Remove this duplicate.

    Signed-off-by: Benson Leung
    Signed-off-by: Olof Johansson

    Benson Leung
     
  • The call to put_i2c_dev() frees "i2c_dev" so there is a use after
    free when we call cdev_del(&i2c_dev->cdev).

    Fixes: d6760b14d4a1 ('i2c: dev: switch from register_chrdev to cdev API')
    Signed-off-by: Dan Carpenter
    Signed-off-by: Wolfram Sang

    Dan Carpenter
     
  • The corresponding FROZEN hotplug notifier transitions used on
    suspend/resume are ignored. Therefore the switch case action argument
    is masked with the frozen hotplug notifier transition mask.

    Signed-off-by: Anna-Maria Gleixner
    Cc: linux-mips@linux-mips.org
    Cc: linux-kernel@vger.kernel.org
    Cc: rt@linutronix.de
    Patchwork: https://patchwork.linux-mips.org/patch/13351/
    Signed-off-by: Ralf Baechle

    Anna-Maria Gleixner
     
  • MicroMIPS kernels may be expected to run on microMIPS only cores which
    don't support the normal MIPS instruction set, so be sure to pass the
    -mmicromips flag through to the VDSO cflags.

    Fixes: ebb5e78cc634 ("MIPS: Initial implementation of a VDSO")
    Signed-off-by: James Hogan
    Cc: Paul Burton
    Cc: linux-mips@linux-mips.org
    Cc: # 4.4.x-
    Patchwork: https://patchwork.linux-mips.org/patch/13349/
    Signed-off-by: Ralf Baechle

    James Hogan