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    SubjectRe: [PATCH v4 14/20] TP-futex: Support userspace reader/writer locks
    Hi Waiman,

    [auto build test WARNING on linus/master]
    [also build test WARNING on v4.10-rc1 next-20161224]
    [if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

    url: https://github.com/0day-ci/linux/commits/Waiman-Long/futex-Introducing-throughput-optimized-TP-futexes/20161230-020021
    config: i386-randconfig-x006-201652 (attached as .config)
    compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
    reproduce:
    # save the attached .config to linux build tree
    make ARCH=i386

    Note: it may well be a FALSE warning. FWIW you are at least aware of it now.
    http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings

    All warnings (new ones prefixed by >>):

    kernel/futex.c: In function 'futex_lock':
    >> kernel/futex.c:3776:13: warning: 'rspin_timeout' may be used uninitialized in this function [-Wmaybe-uninitialized]
    else if (curtime > rspin_timeout)
    ^
    kernel/futex.c:3656:6: note: 'rspin_timeout' was declared here
    u64 rspin_timeout;
    ^~~~~~~~~~~~~

    vim +/rspin_timeout +3776 kernel/futex.c

    3760
    3761 if (!owner_task && (reader_value >= 0)) {
    3762 int old_count = reader_value;
    3763
    3764 /*
    3765 * Reset timeout value if the old reader
    3766 * count is 0 or the reader value changes and
    3767 * handoff time hasn't been reached. Otherwise,
    3768 * disable reader spinning if the handoff time
    3769 * is reached.
    3770 */
    3771 reader_value = (uval & FUTEX_TID_MASK);
    3772 if (!old_count || (!handoff_set
    3773 && (reader_value != old_count)))
    3774 rspin_timeout = curtime +
    3775 TP_RSPIN_TIMEOUT;
    > 3776 else if (curtime > rspin_timeout)
    3777 reader_value = -1;
    3778 }
    3779 if (!handoff_set && (curtime > handoff_time)) {
    3780 WARN_ON(READ_ONCE(state->handoff_pid));
    3781 WRITE_ONCE(state->handoff_pid, vpid);
    3782
    3783 /*
    3784 * Disable handoff check.

    ---
    0-DAY kernel test infrastructure Open Source Technology Center
    https://lists.01.org/pipermail/kbuild-all Intel Corporation
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