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[Bug nptl/18243] sem_wait, sem_timedwait are cancellation points shm_open is not

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- Log -----------------------------------------------------------------;h=fbc994921b459d57b681a926780933a20745edf5

commit fbc994921b459d57b681a926780933a20745edf5
Author: Adhemerval Zanella <>
Date:   Mon Aug 22 10:31:42 2016 -0300

    rt: Set shm_open as a non cancellation point (BZ #18243)

    This patch changes shm_open to not act as a cancellation point.
    Cancellation is disable at start and reenable in function exit.
    It fixes BZ #18243.

    Tested on x86_64 and i686.

        [BZ #18243]
        * rt/Makefile (test): Add tst-shm-cancel.
        * rt/tst-shm-cancel.c: New file.
        * sysdeps/posix/shm_open.c: Disable asynchronous cancellation.;h=47677f2edc815e85d0383a89b09733e95e5d7302

commit 47677f2edc815e85d0383a89b09733e95e5d7302
Author: Adhemerval Zanella <>
Date:   Mon Aug 22 09:39:46 2016 -0300

    nptl: Fix sem_wait and sem_timedwait cancellation (BZ#18243)

    This patch fixes both sem_wait and sem_timedwait cancellation point for
    uncontended case.  In this scenario only atomics are involved and thus
    the futex cancellable call is not issue and a pending cancellation signal
    is not handled.

    The fix is straighforward by calling pthread_testcancel is both function
    start.  Although it would be simpler to call CANCELLATION_P directly, I
    decided to add an internal pthread_testcancel alias and use it to export
    less internal implementation on such function.  A possible change on
    how pthread_testcancel is internally implemented would lead to either
    continue to force use CANCELLATION_P or to adjust its every use.

    GLIBC testcase also does have tests for uncontended cases, test-cancel12
    and test-cancel14.c,  however both are flawed by adding another
    cancellation point just after thread pthread_cleanup_pop:

     47 static void *
     48 tf (void *arg)
     49 {
     50   pthread_cleanup_push (cleanup, NULL);
     52   int e = pthread_barrier_wait (&bar);
     53   if (e != 0 && e != PTHREAD_BARRIER_SERIAL_THREAD)
     54     {
     55       puts ("tf: 1st barrier_wait failed");
     56       exit (1);
     57     }
     59   /* This call should block and be cancelable.  */
     60   sem_wait (&sem);
     62   pthread_cleanup_pop (0);
     64   puts ("sem_wait returned");
     66   return NULL;
     67 }

    So sem_{timed}wait does not act on cancellation, pthread_cleanup_pop
    'cleanup' and then 'puts' acts on cancellation.  Since pthread_cleanup_pop
    removed the clean-up handler, it will ran only once and thus it won't
    an error to indicate sem_wait has not acted on the cancellation signal.

    This patch also fixes this behavior by removing the cancellation point
    It also adds some cleanup on all sem_{timed}wait cancel tests.

    It partially fixes BZ #18243.  Checked on x86_64.

        [BZ #18243]
        * nptl/pthreadP.h (__pthread_testcancel): Add prototype and
        * nptl/pthread_testcancel.c (pthread_cancel): Add internal aliais
        * nptl/sem_timedwait.c (sem_timedwait): Add cancellation check for
        uncontended case.
        * nptl/sem_wait.c (__new_sem_wait): Likewise.
        * nptl/tst-cancel12.c (cleanup): Remove wrong cancellation point.
        (tf): Fix check for uncontended case.
        (do_test): Likewise.
        * nptl/tst-cancel13.c (cleanup): Remove wrong cancellation point.
        (tf): Fix check for uncontended case.
        (do_test): Likewise.
        * nptl/tst-cancel14.c (cleanup): Remove wrong cancellation point.
        (tf): Fix check for uncontended case.
        (do_test): Likewise.
        * nptl/tst-cancel15.c (cleanup): Remove wrong cancellation point.
        (tf): Fix check for uncontended case.
        (do_test): Likewise.;h=49ad334ab10671dabb40eda8beba887ef902f0f3

commit 49ad334ab10671dabb40eda8beba887ef902f0f3
Author: Adhemerval Zanella <>
Date:   Sun Aug 21 17:14:35 2016 -0300

    nptl: Remove sparc sem_wait

    This patch removes the sparc32 sem_wait.c implementation since it is
    identical to default nptl one.  The sparcv9 is no longer required with
    the removal.

    Checked with a sparcv9 build.

        * sysdeps/sparc/sparc32/sem_wait.c: Remove file.
        * sysdeps/sparc/sparc32/sparcv9/sem_wait.c: Likewise.;h=91dd866ff1801b27e1db1e14a52eb89a213627e6

commit 91dd866ff1801b27e1db1e14a52eb89a213627e6
Author: Adhemerval Zanella <>
Date:   Sat Aug 20 11:23:08 2016 -0300

    nptl: Set sem_open as a non cancellation point (BZ #15765)

    This patch changes sem_open to not act as a cancellation point.
    Cancellation is disable at start and reenable in function exit.
    It fixes BZ #15765.

    Tested on x86_64 and i686.

        [BZ #15765]
        * nptl/Makefile (tests): Add tst-sem16.
        * nptl/tst-sem16.c: New file.
        * nptl/sem_open.c (sem_open): Disable asynchronous cancellation.;h=980d25d53e748abd3365aeec0a1ccd1316b4e6d6

commit 980d25d53e748abd3365aeec0a1ccd1316b4e6d6
Author: Adhemerval Zanella <>
Date:   Fri Aug 19 15:30:01 2016 -0300

    nptl: Consolidate sem_open implementations

    Current sparc32 sem_open and default one only differ on:

      1. Default one contains a 'futex_supports_pshared' check.
      2. sem.newsem.pad is initialized to zero.

    This patch removes sparc32 and sparc32v9 sem_open arch specific
    implementation and instead set sparc32 to use nptl default one.
    Using 1. is fine since it should always evaluate 0 for Linux
    (an optimized away by the compiler). Adding 2. to default
    implementation should be ok since 'pad' field is used mainly
    on sparc32 code.

    I checked on i686 and checked a sparc32v9 build.

        * nptl/sem_open.c (sem_open): Init pad value to 0.
        * sysdeps/sparc/sparc32/sem_open.c: Remove file.
        * sysdeps/sparc/sparc32/sparcv9/sem_open.c: Likewise.


Summary of changes:
 ChangeLog                                |   39 ++++
 nptl/Makefile                            |    2 +-
 nptl/pthreadP.h                          |    2 +
 nptl/pthread_testcancel.c                |    4 +-
 nptl/sem_open.c                          |   27 +++-
 nptl/sem_timedwait.c                     |    3 +
 nptl/sem_wait.c                          |   13 ++
 nptl/tst-cancel12.c                      |   29 ++--
 nptl/tst-cancel13.c                      |   23 +--
 nptl/tst-cancel14.c                      |   17 +-
 nptl/tst-cancel15.c                      |   23 +--
 nptl/tst-sem16.c                         |  130 +++++++++++++
 rt/Makefile                              |    2 +-
 rt/tst-shm-cancel.c                      |  130 +++++++++++++
 sysdeps/posix/shm_open.c                 |    7 +
 sysdeps/sparc/sparc32/sem_open.c         |  300 ------------------------------
 sysdeps/sparc/sparc32/sem_wait.c         |   93 ---------
 sysdeps/sparc/sparc32/sparcv9/sem_open.c |    1 -
 sysdeps/sparc/sparc32/sparcv9/sem_wait.c |    1 -
 19 files changed, 393 insertions(+), 453 deletions(-)
 create mode 100644 nptl/tst-sem16.c
 create mode 100644 rt/tst-shm-cancel.c
 delete mode 100644 sysdeps/sparc/sparc32/sem_open.c
 delete mode 100644 sysdeps/sparc/sparc32/sem_wait.c
 delete mode 100644 sysdeps/sparc/sparc32/sparcv9/sem_open.c
 delete mode 100644 sysdeps/sparc/sparc32/sparcv9/sem_wait.c

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