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Problem Report 1369 Details

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Report 1369 Actions

    Problem Report Number 1369
    Submitter's Classification Test Suite problem
    State Resolved
    Resolution Test Suite Deficiency (TSD)
    Problem Resolution ID TSD.X.0651
    Raised 1970-01-01 08:00
    Updated 2003-03-13 08:00
    Published 1996-11-22 08:00
    Product Standard Internationalised System Calls and Libraries Extended (UNIX 95)
    Certification Program The Open Brand certification program
    Test Suite VSU version 4.1.1
    Test Identification Base/sigpause 1
    Problem Summary TSD4U.00166 This test may fail intermittently on slow implementations.
    Problem Text
    We believe that a timing problem in sigpause test #1 causes the test to fail
    intermittently on slow machines.

    In fsigpause1.c, Test1A loops through a defined set of signals, testing
    sigpause for each. Sigpause is tested by forking a child, which performs
    some setup operations, saves the time since the epoch in seconds, issues a
    sigpause(), and waits for the parent process to issue a signal to end the
    pause. When sigpause returns, the child compares the current time to the
    time saved before the call to sigpause. If the difference is less than one
    second, the test fails.

    The parent and child processes are coordinated via POST_EVENT and WAIT_EVENT.
    The parent waits for the coordinating semaphore event, sleeps one second, and
    sends the signal to the child to end the sigpause. The test assumes that the
    sleep(1) ensures that the clock will advance one second, which will show up
    in the difference between time2 and time1.

    We believe this assumption to be false. There is no guarantee that the parent
    or child will be scheduled in any particular order or manner following returns
    from WAIT_EVENT and POST_EVENT. For example, if the parent returns from
    WAIT_EVENT and is scheduled to run prior to the child, there should be no
    expectation that the child will run before the parent begins its sleep or, for
    that matter, before it ends its sleep and sends the signal. Because of this,
    there is no guarantee that the calls to time() in the child will occur in a
    manner that ensures that one second will elapse between the first call to
    time() and the generation of the signal in the parent.

    For instance:

    Child Parent

    POST_EVENT WAIT_EVENT
    | |
    T | Scheduled after WAIT_EVENT
    I | |
    M | Starts sleep(1)
    E | |
    | Schedules after POST_EVENT |
    | | |
    V Gets time1 |
    | |
    Calls sigpause() |
    | |
    | Sends signal
    | |
    Wakes |
    | |
    Gets time2 o
    |
    o


    In the scenario diagrammed above, the parent schedules before the child, which
    causes it to sleep before the child records time1. This causes the signal
    sent by the parent to be generated before sigpause has a chance to rest for
    a full second.

    Practically speaking, the child usually runs quickly enough for the test to
    pass on fast machines. On slower machines, however, this isn't always the
    case.

    In order to increase the likelihood of the timing cycle in the child coinciding
    with the sleep in the parent, we suggest increasing the length of the sleep by
    by one. When we did this, we found the extra second allowed the child to be
    scheduled in time to pause at least a second, even on a slow, heavily-loaded
    system. Please note that while we have inductive evidence that the suggested
    change makes the problem less likely to occur, the change does not fix the
    test and may not work on some systems.
    Test Output
    TEST PURPOSE #1
    A successful call to int sigpause(int sig) shall
    remove sig from the calling process's signal mask,
    suspend the calling process until it receives a
    signal, then return -1, and set errno to EINTR.
    PREP: Fork child to test sig=6 (SIGABRT)
    PREP: Set signal mask
    TEST: sigpause() suspends execution
    TEST: sigpause() returns -1 and sets errno to EINTR
    TEST: sigpause() removed signal from mask
    PREP: Fork child to test sig=14 (SIGALRM)
    PREP: Set signal mask
    TEST: sigpause() suspends execution
    TEST: sigpause() returns -1 and sets errno to EINTR
    TEST: sigpause() removed signal from mask
    PREP: Fork child to test sig=18 (SIGCHLD)
    PREP: Set signal mask
    TEST: sigpause() suspends execution
    TEST: sigpause() returns -1 and sets errno to EINTR
    TEST: sigpause() removed signal from mask
    PREP: Fork child to test sig=25 (SIGCONT)
    PREP: Set signal mask
    TEST: sigpause() suspends execution
    TEST: sigpause() returns -1 and sets errno to EINTR
    TEST: sigpause() removed signal from mask
    PREP: Fork child to test sig=8 (SIGFPE)
    PREP: Set signal mask
    TEST: sigpause() suspends execution
    TEST: sigpause() returns -1 and sets errno to EINTR
    TEST: sigpause() removed signal from mask
    PREP: Fork child to test sig=1 (SIGHUP)
    PREP: Set signal mask
    TEST: sigpause() suspends execution
    TEST: sigpause() returns -1 and sets errno to EINTR
    TEST: sigpause() removed signal from mask
    PREP: Fork child to test sig=4 (SIGILL)
    PREP: Set signal mask
    TEST: sigpause() suspends execution
    TEST: sigpause() returns -1 and sets errno to EINTR
    TEST: sigpause() removed signal from mask
    PREP: Fork child to test sig=2 (SIGINT)
    PREP: Set signal mask
    TEST: sigpause() suspends execution
    TEST: sigpause() returns -1 and sets errno to EINTR
    TEST: sigpause() removed signal from mask
    PREP: Fork child to test sig=13 (SIGPIPE)
    PREP: Set signal mask
    TEST: sigpause() suspends execution
    TEST: sigpause() returns -1 and sets errno to EINTR
    TEST: sigpause() removed signal from mask
    PREP: Fork child to test sig=3 (SIGQUIT)
    PREP: Set signal mask
    TEST: sigpause() suspends execution
    TEST: sigpause() returns -1 and sets errno to EINTR
    TEST: sigpause() removed signal from mask
    PREP: Fork child to test sig=11 (SIGSEGV)
    PREP: Set signal mask
    TEST: sigpause() suspends execution
    TEST: sigpause() returns -1 and sets errno to EINTR
    TEST: sigpause() removed signal from mask
    PREP: Fork child to test sig=15 (SIGTERM)
    PREP: Set signal mask
    TEST: sigpause() suspends execution
    TEST: sigpause() returns -1 and sets errno to EINTR
    TEST: sigpause() removed signal from mask
    PREP: Fork child to test sig=24 (SIGTSTP)
    PREP: Set signal mask
    TEST: sigpause() suspends execution
    TEST: sigpause() returns -1 and sets errno to EINTR
    TEST: sigpause() removed signal from mask
    PREP: Fork child to test sig=26 (SIGTTIN)
    PREP: Set signal mask
    TEST: sigpause() suspends execution
    TEST: sigpause() returns -1 and sets errno to EINTR
    TEST: sigpause() removed signal from mask
    PREP: Fork child to test sig=27 (SIGTTOU)
    PREP: Set signal mask
    TEST: sigpause() suspends execution
    TEST: sigpause() returns -1 and sets errno to EINTR
    TEST: sigpause() removed signal from mask
    PREP: Fork child to test sig=16 (SIGUSR1)
    PREP: Set signal mask
    TEST: sigpause() suspends execution
    ERROR: sigpause() did not suspend calling process
    Expected 1 second wait,Received 0 second wait
    TEST: sigpause() returns -1 and sets errno to EINTR
    TEST: sigpause() removed signal from mask
    PREP: Fork child to test sig=17 (SIGUSR2)
    PREP: Set signal mask
    TEST: sigpause() suspends execution
    TEST: sigpause() returns -1 and sets errno to EINTR
    TEST: sigpause() removed signal from mask
    PREP: Fork child to test sig=5 (SIGTRAP)
    PREP: Set signal mask
    TEST: sigpause() suspends execution
    TEST: sigpause() returns -1 and sets errno to EINTR
    TEST: sigpause() removed signal from mask
    PREP: Fork child to test sig=10 (SIGBUS)
    PREP: Set signal mask
    TEST: sigpause() suspends execution
    TEST: sigpause() returns -1 and sets errno to EINTR
    TEST: sigpause() removed signal from mask
    PREP: Fork child to test sig=12 (SIGSYS)
    PREP: Set signal mask
    TEST: sigpause() suspends execution
    TEST: sigpause() returns -1 and sets errno to EINTR
    TEST: sigpause() removed signal from mask
    PREP: Fork child to test sig=22 (SIGPOLL)
    PREP: Set signal mask
    TEST: sigpause() suspends execution
    TEST: sigpause() returns -1 and sets errno to EINTR
    TEST: sigpause() removed signal from mask
    PREP: Fork child to test sig=29 (SIGPROF)
    PREP: Set signal mask
    TEST: sigpause() suspends execution
    TEST: sigpause() returns -1 and sets errno to EINTR
    TEST: sigpause() removed signal from mask
    PREP: Fork child to test sig=30 (SIGXCPU)
    PREP: Set signal mask
    TEST: sigpause() suspends execution
    TEST: sigpause() returns -1 and sets errno to EINTR
    TEST: sigpause() removed signal from mask
    PREP: Fork child to test sig=31 (SIGXFSZ)
    PREP: Set signal mask
    TEST: sigpause() suspends execution
    TEST: sigpause() returns -1 and sets errno to EINTR
    TEST: sigpause() removed signal from mask
    PREP: Fork child to test sig=21 (SIGURG)
    PREP: Set signal mask
    TEST: sigpause() suspends execution
    TEST: sigpause() returns -1 and sets errno to EINTR
    TEST: sigpause() removed signal from mask
    PREP: Fork child to test sig=28 (SIGVTALRM)
    PREP: Set signal mask
    TEST: sigpause() suspends execution
    TEST: sigpause() returns -1 and sets errno to EINTR
    TEST: sigpause() removed signal from mask

    Review Information

    Review Type TSMA Review
    Start Date null
    Completed null
    Status Complete
    Review Recommendation No Resolution Given
    Review Response
    We agree this is a test suite deficiency in the test
    suite version(s) listed.

    In the future, in order for a vendor to site this TSD in
    support of a test report showing failures of these tests,
    the vendor must also provide results for these tests
    from a run in which they did not fail, so as to illustrate the
    intermittent failure documented here is in fact the problem
    encountered.

    Review Type SA Review
    Start Date null
    Completed null
    Status Complete
    Review Resolution Test Suite Deficiency (TSD)
    Review Conclusion
    This is an agreed Test Suite Deficiency.

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