[Bug nptl/23275] Race in pthread_mutex_lock while promoting to PTHREAD_MUTEX_ELISION_NP.

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https://sourceware.org/bugzilla/show_bug.cgi?id=23275

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- Log -----------------------------------------------------------------
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=314e181dc90cb290942d8b2b57823306ae956696

commit 314e181dc90cb290942d8b2b57823306ae956696
Author: Stefan Liebler <stli@linux.ibm.com>
Date:   Wed Oct 17 12:23:04 2018 +0200

    Fix race in pthread_mutex_lock while promoting to PTHREAD_MUTEX_ELISION_NP
[BZ #23275]

    The race leads either to pthread_mutex_destroy returning EBUSY
    or triggering an assertion (See description in bugzilla).

    This patch is fixing the race by ensuring that the elision path is
    used in all cases if elision is enabled by the GLIBC_TUNABLES framework.

    The __kind variable in struct __pthread_mutex_s is accessed concurrently.
    Therefore we are now using the atomic macros.

    The new testcase tst-mutex10 is triggering the race on s390x and intel.
    Presumably also on power, but I don't have access to a power machine
    with lock-elision. At least the code for power is the same as on the other
    two architectures.

    ChangeLog:

        [BZ #23275]
        * nptl/tst-mutex10.c: New File.
        * nptl/Makefile (tests): Add tst-mutex10.
        (tst-mutex10-ENV): New variable.
        * sysdeps/unix/sysv/linux/s390/force-elision.h: (FORCE_ELISION):
        Ensure that elision path is used if elision is available.
        * sysdeps/unix/sysv/linux/powerpc/force-elision.h (FORCE_ELISION):
        Likewise.
        * sysdeps/unix/sysv/linux/x86/force-elision.h: (FORCE_ELISION):
        Likewise.
        * nptl/pthreadP.h (PTHREAD_MUTEX_TYPE, PTHREAD_MUTEX_TYPE_ELISION)
        (PTHREAD_MUTEX_PSHARED): Use atomic_load_relaxed.
        * nptl/pthread_mutex_consistent.c (pthread_mutex_consistent): Likewise.
        * nptl/pthread_mutex_getprioceiling.c (pthread_mutex_getprioceiling):
        Likewise.
        * nptl/pthread_mutex_lock.c (__pthread_mutex_lock_full)
        (__pthread_mutex_cond_lock_adjust): Likewise.
        * nptl/pthread_mutex_setprioceiling.c (pthread_mutex_setprioceiling):
        Likewise.
        * nptl/pthread_mutex_timedlock.c (__pthread_mutex_timedlock): Likewise.
        * nptl/pthread_mutex_trylock.c (__pthread_mutex_trylock): Likewise.
        * nptl/pthread_mutex_unlock.c (__pthread_mutex_unlock_full): Likewise.
        * sysdeps/nptl/bits/thread-shared-types.h (struct __pthread_mutex_s):
        Add comments.
        * nptl/pthread_mutex_destroy.c (__pthread_mutex_destroy):
        Use atomic_load_relaxed and atomic_store_relaxed.
        * nptl/pthread_mutex_init.c (__pthread_mutex_init):
        Use atomic_store_relaxed.

    (cherry picked from commit 403b4feb22dcbc85ace72a361d2a951380372471)

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog                                       |   31 +++++++
 nptl/Makefile                                   |    8 +-
 nptl/pthreadP.h                                 |   12 ++-
 nptl/pthread_mutex_consistent.c                 |    7 +-
 nptl/pthread_mutex_destroy.c                    |   11 ++-
 nptl/pthread_mutex_getprioceiling.c             |    4 +-
 nptl/pthread_mutex_init.c                       |   14 ++-
 nptl/pthread_mutex_lock.c                       |   28 +++++--
 nptl/pthread_mutex_setprioceiling.c             |    7 +-
 nptl/pthread_mutex_timedlock.c                  |   17 +++-
 nptl/pthread_mutex_trylock.c                    |   17 +++-
 nptl/pthread_mutex_unlock.c                     |   17 +++-
 nptl/tst-mutex10.c                              |  109 +++++++++++++++++++++++
 sysdeps/nptl/bits/thread-shared-types.h         |   22 +++++-
 sysdeps/unix/sysv/linux/powerpc/force-elision.h |   44 ++++++++-
 sysdeps/unix/sysv/linux/s390/force-elision.h    |   44 ++++++++-
 sysdeps/unix/sysv/linux/x86/force-elision.h     |   44 ++++++++-
 17 files changed, 386 insertions(+), 50 deletions(-)
 create mode 100644 nptl/tst-mutex10.c

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