1. 26 Sep, 2019 1 commit
  2. 08 Mar, 2019 2 commits
  3. 06 Feb, 2019 1 commit
    • Arnd Bergmann's avatar
      y2038: syscalls: rename y2038 compat syscalls · 8dabe724
      Arnd Bergmann authored
      
      A lot of system calls that pass a time_t somewhere have an implementation
      using a COMPAT_SYSCALL_DEFINEx() on 64-bit architectures, and have
      been reworked so that this implementation can now be used on 32-bit
      architectures as well.
      
      The missing step is to redefine them using the regular SYSCALL_DEFINEx()
      to get them out of the compat namespace and make it possible to build them
      on 32-bit architectures.
      
      Any system call that ends in 'time' gets a '32' suffix on its name for
      that version, while the others get a '_time32' suffix, to distinguish
      them from the normal version, which takes a 64-bit time argument in the
      future.
      
      In this step, only 64-bit architectures are changed, doing this rename
      first lets us avoid touching the 32-bit architectures twice.
      Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
      Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
      8dabe724
  4. 25 Jan, 2019 1 commit
    • Arnd Bergmann's avatar
      ipc: rename old-style shmctl/semctl/msgctl syscalls · 275f2214
      Arnd Bergmann authored
      
      The behavior of these system calls is slightly different between
      architectures, as determined by the CONFIG_ARCH_WANT_IPC_PARSE_VERSION
      symbol. Most architectures that implement the split IPC syscalls don't set
      that symbol and only get the modern version, but alpha, arm, microblaze,
      mips-n32, mips-n64 and xtensa expect the caller to pass the IPC_64 flag.
      
      For the architectures that so far only implement sys_ipc(), i.e. m68k,
      mips-o32, powerpc, s390, sh, sparc, and x86-32, we want the new behavior
      when adding the split syscalls, so we need to distinguish between the
      two groups of architectures.
      
      The method I picked for this distinction is to have a separate system call
      entry point: sys_old_*ctl() now uses ipc_parse_version, while sys_*ctl()
      does not. The system call tables of the five architectures are changed
      accordingly.
      
      As an additional benefit, we no longer need the configuration specific
      definition for ipc_parse_version(), it always does the same thing now,
      but simply won't get called on architectures with the modern interface.
      
      A small downside is that on architectures that do set
      ARCH_WANT_IPC_PARSE_VERSION, we now have an extra set of entry points
      that are never called. They only add a few bytes of bloat, so it seems
      better to keep them compared to adding yet another Kconfig symbol.
      I considered adding new syscall numbers for the IPC_64 variants for
      consistency, but decided against that for now.
      Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
      275f2214
  5. 27 Aug, 2018 1 commit
    • Arnd Bergmann's avatar
      y2038: globally rename compat_time to old_time32 · 9afc5eee
      Arnd Bergmann authored
      
      Christoph Hellwig suggested a slightly different path for handling
      backwards compatibility with the 32-bit time_t based system calls:
      
      Rather than simply reusing the compat_sys_* entry points on 32-bit
      architectures unchanged, we get rid of those entry points and the
      compat_time types by renaming them to something that makes more sense
      on 32-bit architectures (which don't have a compat mode otherwise),
      and then share the entry points under the new name with the 64-bit
      architectures that use them for implementing the compatibility.
      
      The following types and interfaces are renamed here, and moved
      from linux/compat_time.h to linux/time32.h:
      
      old				new
      ---				---
      compat_time_t			old_time32_t
      struct compat_timeval		struct old_timeval32
      struct compat_timespec		struct old_timespec32
      struct compat_itimerspec	struct old_itimerspec32
      ns_to_compat_timeval()		ns_to_old_timeval32()
      get_compat_itimerspec64()	get_old_itimerspec32()
      put_compat_itimerspec64()	put_old_itimerspec32()
      compat_get_timespec64()		get_old_timespec32()
      compat_put_timespec64()		put_old_timespec32()
      
      As we already have aliases in place, this patch addresses only the
      instances that are relevant to the system call interface in particular,
      not those that occur in device drivers and other modules. Those
      will get handled separately, while providing the 64-bit version
      of the respective interfaces.
      
      I'm not renaming the timex, rusage and itimerval structures, as we are
      still debating what the new interface will look like, and whether we
      will need a replacement at all.
      
      This also doesn't change the names of the syscall entry points, which can
      be done more easily when we actually switch over the 32-bit architectures
      to use them, at that point we need to change COMPAT_SYSCALL_DEFINEx to
      SYSCALL_DEFINEx with a new name, e.g. with a _time32 suffix.
      Suggested-by: default avatarChristoph Hellwig <hch@infradead.org>
      Link: https://lore.kernel.org/lkml/20180705222110.GA5698@infradead.org/
      
      Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
      9afc5eee
  6. 22 Aug, 2018 5 commits
  7. 27 Jul, 2018 1 commit
  8. 22 Jun, 2018 1 commit
    • NeilBrown's avatar
      rhashtable: split rhashtable.h · 0eb71a9d
      NeilBrown authored
      
      Due to the use of rhashtables in net namespaces,
      rhashtable.h is included in lots of the kernel,
      so a small changes can required a large recompilation.
      This makes development painful.
      
      This patch splits out rhashtable-types.h which just includes
      the major type declarations, and does not include (non-trivial)
      inline code.  rhashtable.h is no longer included by anything
      in the include/ directory.
      Common include files only include rhashtable-types.h so a large
      recompilation is only triggered when that changes.
      Acked-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
      Signed-off-by: default avatarNeilBrown <neilb@suse.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      0eb71a9d
  9. 14 Jun, 2018 1 commit
  10. 12 Jun, 2018 1 commit
    • Kees Cook's avatar
      treewide: kvmalloc() -> kvmalloc_array() · 344476e1
      Kees Cook authored
      
      The kvmalloc() function has a 2-factor argument form, kvmalloc_array(). This
      patch replaces cases of:
      
              kvmalloc(a * b, gfp)
      
      with:
              kvmalloc_array(a * b, gfp)
      
      as well as handling cases of:
      
              kvmalloc(a * b * c, gfp)
      
      with:
      
              kvmalloc(array3_size(a, b, c), gfp)
      
      as it's slightly less ugly than:
      
              kvmalloc_array(array_size(a, b), c, gfp)
      
      This does, however, attempt to ignore constant size factors like:
      
              kvmalloc(4 * 1024, gfp)
      
      though any constants defined via macros get caught up in the conversion.
      
      Any factors with a sizeof() of "unsigned char", "char", and "u8" were
      dropped, since they're redundant.
      
      The Coccinelle script used for this was:
      
      // Fix redundant parens around sizeof().
      @@
      type TYPE;
      expression THING, E;
      @@
      
      (
        kvmalloc(
      -	(sizeof(TYPE)) * E
      +	sizeof(TYPE) * E
        , ...)
      |
        kvmalloc(
      -	(sizeof(THING)) * E
      +	sizeof(THING) * E
        , ...)
      )
      
      // Drop single-byte sizes and redundant parens.
      @@
      expression COUNT;
      typedef u8;
      typedef __u8;
      @@
      
      (
        kvmalloc(
      -	sizeof(u8) * (COUNT)
      +	COUNT
        , ...)
      |
        kvmalloc(
      -	sizeof(__u8) * (COUNT)
      +	COUNT
        , ...)
      |
        kvmalloc(
      -	sizeof(char) * (COUNT)
      +	COUNT
        , ...)
      |
        kvmalloc(
      -	sizeof(unsigned char) * (COUNT)
      +	COUNT
        , ...)
      |
        kvmalloc(
      -	sizeof(u8) * COUNT
      +	COUNT
        , ...)
      |
        kvmalloc(
      -	sizeof(__u8) * COUNT
      +	COUNT
        , ...)
      |
        kvmalloc(
      -	sizeof(char) * COUNT
      +	COUNT
        , ...)
      |
        kvmalloc(
      -	sizeof(unsigned char) * COUNT
      +	COUNT
        , ...)
      )
      
      // 2-factor product with sizeof(type/expression) and identifier or constant.
      @@
      type TYPE;
      expression THING;
      identifier COUNT_ID;
      constant COUNT_CONST;
      @@
      
      (
      - kvmalloc
      + kvmalloc_array
        (
      -	sizeof(TYPE) * (COUNT_ID)
      +	COUNT_ID, sizeof(TYPE)
        , ...)
      |
      - kvmalloc
      + kvmalloc_array
        (
      -	sizeof(TYPE) * COUNT_ID
      +	COUNT_ID, sizeof(TYPE)
        , ...)
      |
      - kvmalloc
      + kvmalloc_array
        (
      -	sizeof(TYPE) * (COUNT_CONST)
      +	COUNT_CONST, sizeof(TYPE)
        , ...)
      |
      - kvmalloc
      + kvmalloc_array
        (
      -	sizeof(TYPE) * COUNT_CONST
      +	COUNT_CONST, sizeof(TYPE)
        , ...)
      |
      - kvmalloc
      + kvmalloc_array
        (
      -	sizeof(THING) * (COUNT_ID)
      +	COUNT_ID, sizeof(THING)
        , ...)
      |
      - kvmalloc
      + kvmalloc_array
        (
      -	sizeof(THING) * COUNT_ID
      +	COUNT_ID, sizeof(THING)
        , ...)
      |
      - kvmalloc
      + kvmalloc_array
        (
      -	sizeof(THING) * (COUNT_CONST)
      +	COUNT_CONST, sizeof(THING)
        , ...)
      |
      - kvmalloc
      + kvmalloc_array
        (
      -	sizeof(THING) * COUNT_CONST
      +	COUNT_CONST, sizeof(THING)
        , ...)
      )
      
      // 2-factor product, only identifiers.
      @@
      identifier SIZE, COUNT;
      @@
      
      - kvmalloc
      + kvmalloc_array
        (
      -	SIZE * COUNT
      +	COUNT, SIZE
        , ...)
      
      // 3-factor product with 1 sizeof(type) or sizeof(expression), with
      // redundant parens removed.
      @@
      expression THING;
      identifier STRIDE, COUNT;
      type TYPE;
      @@
      
      (
        kvmalloc(
      -	sizeof(TYPE) * (COUNT) * (STRIDE)
      +	array3_size(COUNT, STRIDE, sizeof(TYPE))
        , ...)
      |
        kvmalloc(
      -	sizeof(TYPE) * (COUNT) * STRIDE
      +	array3_size(COUNT, STRIDE, sizeof(TYPE))
        , ...)
      |
        kvmalloc(
      -	sizeof(TYPE) * COUNT * (STRIDE)
      +	array3_size(COUNT, STRIDE, sizeof(TYPE))
        , ...)
      |
        kvmalloc(
      -	sizeof(TYPE) * COUNT * STRIDE
      +	array3_size(COUNT, STRIDE, sizeof(TYPE))
        , ...)
      |
        kvmalloc(
      -	sizeof(THING) * (COUNT) * (STRIDE)
      +	array3_size(COUNT, STRIDE, sizeof(THING))
        , ...)
      |
        kvmalloc(
      -	sizeof(THING) * (COUNT) * STRIDE
      +	array3_size(COUNT, STRIDE, sizeof(THING))
        , ...)
      |
        kvmalloc(
      -	sizeof(THING) * COUNT * (STRIDE)
      +	array3_size(COUNT, STRIDE, sizeof(THING))
        , ...)
      |
        kvmalloc(
      -	sizeof(THING) * COUNT * STRIDE
      +	array3_size(COUNT, STRIDE, sizeof(THING))
        , ...)
      )
      
      // 3-factor product with 2 sizeof(variable), with redundant parens removed.
      @@
      expression THING1, THING2;
      identifier COUNT;
      type TYPE1, TYPE2;
      @@
      
      (
        kvmalloc(
      -	sizeof(TYPE1) * sizeof(TYPE2) * COUNT
      +	array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2))
        , ...)
      |
        kvmalloc(
      -	sizeof(TYPE1) * sizeof(THING2) * (COUNT)
      +	array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2))
        , ...)
      |
        kvmalloc(
      -	sizeof(THING1) * sizeof(THING2) * COUNT
      +	array3_size(COUNT, sizeof(THING1), sizeof(THING2))
        , ...)
      |
        kvmalloc(
      -	sizeof(THING1) * sizeof(THING2) * (COUNT)
      +	array3_size(COUNT, sizeof(THING1), sizeof(THING2))
        , ...)
      |
        kvmalloc(
      -	sizeof(TYPE1) * sizeof(THING2) * COUNT
      +	array3_size(COUNT, sizeof(TYPE1), sizeof(THING2))
        , ...)
      |
        kvmalloc(
      -	sizeof(TYPE1) * sizeof(THING2) * (COUNT)
      +	array3_size(COUNT, sizeof(TYPE1), sizeof(THING2))
        , ...)
      )
      
      // 3-factor product, only identifiers, with redundant parens removed.
      @@
      identifier STRIDE, SIZE, COUNT;
      @@
      
      (
        kvmalloc(
      -	(COUNT) * STRIDE * SIZE
      +	array3_size(COUNT, STRIDE, SIZE)
        , ...)
      |
        kvmalloc(
      -	COUNT * (STRIDE) * SIZE
      +	array3_size(COUNT, STRIDE, SIZE)
        , ...)
      |
        kvmalloc(
      -	COUNT * STRIDE * (SIZE)
      +	array3_size(COUNT, STRIDE, SIZE)
        , ...)
      |
        kvmalloc(
      -	(COUNT) * (STRIDE) * SIZE
      +	array3_size(COUNT, STRIDE, SIZE)
        , ...)
      |
        kvmalloc(
      -	COUNT * (STRIDE) * (SIZE)
      +	array3_size(COUNT, STRIDE, SIZE)
        , ...)
      |
        kvmalloc(
      -	(COUNT) * STRIDE * (SIZE)
      +	array3_size(COUNT, STRIDE, SIZE)
        , ...)
      |
        kvmalloc(
      -	(COUNT) * (STRIDE) * (SIZE)
      +	array3_size(COUNT, STRIDE, SIZE)
        , ...)
      |
        kvmalloc(
      -	COUNT * STRIDE * SIZE
      +	array3_size(COUNT, STRIDE, SIZE)
        , ...)
      )
      
      // Any remaining multi-factor products, first at least 3-factor products,
      // when they're not all constants...
      @@
      expression E1, E2, E3;
      constant C1, C2, C3;
      @@
      
      (
        kvmalloc(C1 * C2 * C3, ...)
      |
        kvmalloc(
      -	(E1) * E2 * E3
      +	array3_size(E1, E2, E3)
        , ...)
      |
        kvmalloc(
      -	(E1) * (E2) * E3
      +	array3_size(E1, E2, E3)
        , ...)
      |
        kvmalloc(
      -	(E1) * (E2) * (E3)
      +	array3_size(E1, E2, E3)
        , ...)
      |
        kvmalloc(
      -	E1 * E2 * E3
      +	array3_size(E1, E2, E3)
        , ...)
      )
      
      // And then all remaining 2 factors products when they're not all constants,
      // keeping sizeof() as the second factor argument.
      @@
      expression THING, E1, E2;
      type TYPE;
      constant C1, C2, C3;
      @@
      
      (
        kvmalloc(sizeof(THING) * C2, ...)
      |
        kvmalloc(sizeof(TYPE) * C2, ...)
      |
        kvmalloc(C1 * C2 * C3, ...)
      |
        kvmalloc(C1 * C2, ...)
      |
      - kvmalloc
      + kvmalloc_array
        (
      -	sizeof(TYPE) * (E2)
      +	E2, sizeof(TYPE)
        , ...)
      |
      - kvmalloc
      + kvmalloc_array
        (
      -	sizeof(TYPE) * E2
      +	E2, sizeof(TYPE)
        , ...)
      |
      - kvmalloc
      + kvmalloc_array
        (
      -	sizeof(THING) * (E2)
      +	E2, sizeof(THING)
        , ...)
      |
      - kvmalloc
      + kvmalloc_array
        (
      -	sizeof(THING) * E2
      +	E2, sizeof(THING)
        , ...)
      |
      - kvmalloc
      + kvmalloc_array
        (
      -	(E1) * E2
      +	E1, E2
        , ...)
      |
      - kvmalloc
      + kvmalloc_array
        (
      -	(E1) * (E2)
      +	E1, E2
        , ...)
      |
      - kvmalloc
      + kvmalloc_array
        (
      -	E1 * E2
      +	E1, E2
        , ...)
      )
      Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      344476e1
  11. 20 Apr, 2018 4 commits
    • Arnd Bergmann's avatar
      y2038: ipc: Enable COMPAT_32BIT_TIME · b0d17578
      Arnd Bergmann authored
      
      Three ipc syscalls (mq_timedsend, mq_timedreceive and and semtimedop)
      take a timespec argument. After we move 32-bit architectures over to
      useing 64-bit time_t based syscalls, we need seperate entry points for
      the old 32-bit based interfaces.
      
      This changes the #ifdef guards for the existing 32-bit compat syscalls
      to check for CONFIG_COMPAT_32BIT_TIME instead, which will then be
      enabled on all existing 32-bit architectures.
      Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
      b0d17578
    • Arnd Bergmann's avatar
      y2038: ipc: Use __kernel_timespec · 21fc538d
      Arnd Bergmann authored
      
      This is a preparatation for changing over __kernel_timespec to 64-bit
      times, which involves assigning new system call numbers for mq_timedsend(),
      mq_timedreceive() and semtimedop() for compatibility with future y2038
      proof user space.
      
      The existing ABIs will remain available through compat code.
      Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
      21fc538d
    • Arnd Bergmann's avatar
      y2038: ipc: Report long times to user space · c2ab975c
      Arnd Bergmann authored
      
      The shmid64_ds/semid64_ds/msqid64_ds data structures have been extended
      to contain extra fields for storing the upper bits of the time stamps,
      this patch does the other half of the job and and fills the new fields on
      32-bit architectures as well as 32-bit tasks running on a 64-bit kernel
      in compat mode.
      
      There should be no change for native 64-bit tasks.
      Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
      c2ab975c
    • Arnd Bergmann's avatar
      y2038: ipc: Use ktime_get_real_seconds consistently · 2a70b787
      Arnd Bergmann authored
      
      In some places, we still used get_seconds() instead of
      ktime_get_real_seconds(), and I'm changing the remaining ones now to
      all use ktime_get_real_seconds() so we use the full available range for
      timestamps instead of overflowing the 'unsigned long' return value in
      year 2106 on 32-bit kernels.
      Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
      2a70b787
  12. 11 Apr, 2018 1 commit
    • Davidlohr Bueso's avatar
      ipc/sem: introduce semctl(SEM_STAT_ANY) · a280d6dc
      Davidlohr Bueso authored
      There is a permission discrepancy when consulting shm ipc object
      metadata between /proc/sysvipc/sem (0444) and the SEM_STAT semctl
      command.  The later does permission checks for the object vs S_IRUGO.
      As such there can be cases where EACCESS is returned via syscall but the
      info is displayed anyways in the procfs files.
      
      While this might have security implications via info leaking (albeit no
      writing to the sma metadata), this behavior goes way back and showing
      all the objects regardless of the permissions was most likely an
      overlook - so we are stuck with it.  Furthermore, modifying either the
      syscall or the procfs file can cause userspace programs to break (ie
      ipcs).  Some applications require getting the procfs info (without root
      privileges) and can be rather slow in comparison with a syscall -- up to
      500x in some reported cases for shm.
      
      This patch introduces a new SEM_STAT_ANY command such that the sem ipc
      object permissions are ignored, and only audited instead.  In addition,
      I've left the lsm security hook checks in place, as if some policy can
      block the call, then the user has no other choice than just parsing the
      procfs file.
      
      Link: http://lkml.kernel.org/r/20180215162458.10059-3-dave@stgolabs.net
      
      Signed-off-by: default avatarDavidlohr Bueso <dbueso@suse.de>
      Reported-by: default avatarRobert Kettler <robert.kettler@outlook.com>
      Cc: Eric W. Biederman <ebiederm@xmission.com>
      Cc: Kees Cook <keescook@chromium.org>
      Cc: Manfred Spraul <manfred@colorfullife.com>
      Cc: Michael Kerrisk <mtk.manpages@gmail.com>
      Cc: Michal Hocko <mhocko@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      a280d6dc
  13. 02 Apr, 2018 3 commits
  14. 27 Mar, 2018 2 commits
    • Eric W. Biederman's avatar
      ipc: Directly call the security hook in ipc_ops.associate · 50ab44b1
      Eric W. Biederman authored
      
      After the last round of cleanups the shm, sem, and msg associate
      operations just became trivial wrappers around the appropriate security
      method.  Simplify things further by just calling the security method
      directly.
      Signed-off-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
      50ab44b1
    • Eric W. Biederman's avatar
      ipc/sem: Fix semctl(..., GETPID, ...) between pid namespaces · 51d6f263
      Eric W. Biederman authored
      Today the last process to update a semaphore is remembered and
      reported in the pid namespace of that process.  If there are processes
      in any other pid namespace querying that process id with GETPID the
      result will be unusable nonsense as it does not make any
      sense in your own pid namespace.
      
      Due to ipc_update_pid I don't think you will be able to get System V
      ipc semaphores into a troublesome cache line ping-pong.  Using struct
      pids from separate process are not a problem because they do not share
      a cache line.  Using struct pid from different threads of the same
      process are unlikely to be a problem as the reference count update
      can be avoided.
      
      Further linux futexes are a much better tool for the job of mutual
      exclusion between processes than System V semaphores.  So I expect
      programs that  are performance limited by their interprocess mutual
      exclusion primitive will be using futexes.
      
      So while it is possible that enhancing the storage of the last
      rocess of a System V semaphore from an integer to a struct pid
      will cause a performance regression because of the effect
      of frequently updating the pid reference count.  I don't expect
      that to happen in practice.
      
      This change updates semctl(..., GETPID, ...) to return the
      process id of the last process to update a semphore inthe
      pid namespace of the calling process.
      
      Fixes: b488893a
      
       ("pid namespaces: changes to show virtual ids to user")
      Signed-off-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
      51d6f263
  15. 23 Mar, 2018 2 commits
  16. 07 Feb, 2018 1 commit
  17. 18 Nov, 2017 1 commit
  18. 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...
      b2441318
  19. 11 Oct, 2017 1 commit
  20. 09 Sep, 2017 4 commits
  21. 04 Sep, 2017 2 commits
  22. 17 Aug, 2017 1 commit
    • Paul E. McKenney's avatar
      ipc: Replace spin_unlock_wait() with lock/unlock pair · e0892e08
      Paul E. McKenney authored
      
      There is no agreed-upon definition of spin_unlock_wait()'s semantics,
      and it appears that all callers could do just as well with a lock/unlock
      pair.  This commit therefore replaces the spin_unlock_wait() call in
      exit_sem() with spin_lock() followed immediately by spin_unlock().
      This should be safe from a performance perspective because exit_sem()
      is rarely invoked in production.
      Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Davidlohr Bueso <dave@stgolabs.net>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Alan Stern <stern@rowland.harvard.edu>
      Cc: Andrea Parri <parri.andrea@gmail.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Acked-by: default avatarManfred Spraul <manfred@colorfullife.com>
      e0892e08
  23. 03 Aug, 2017 1 commit
  24. 16 Jul, 2017 1 commit