view auto/feature @ 6080:4296627f385a stable-1.6

Core: fixed a race resulting in extra sem_post()'s. The mtx->wait counter was not decremented if we were able to obtain the lock right after incrementing it. This resulted in unneeded sem_post() calls, eventually leading to EOVERFLOW errors being logged, "sem_post() failed while wake shmtx (75: Value too large for defined data type)". To close the race, mtx->wait is now decremented if we obtain the lock right after incrementing it in ngx_shmtx_lock(). The result can become -1 if a concurrent ngx_shmtx_unlock() decrements mtx->wait before the added code does. However, that only leads to one extra iteration in the next call of ngx_shmtx_lock().
author Roman Arutyunyan <arut@nginx.com>
date Wed, 04 Feb 2015 16:22:43 +0300
parents 434548349838
children e3faa5fb7772
line wrap: on
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# Copyright (C) Igor Sysoev
# Copyright (C) Nginx, Inc.


echo $ngx_n "checking for $ngx_feature ...$ngx_c"

cat << END >> $NGX_AUTOCONF_ERR

----------------------------------------
checking for $ngx_feature

END

ngx_found=no

if test -n "$ngx_feature_name"; then
    ngx_have_feature=`echo $ngx_feature_name \
                   | tr abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLMNOPQRSTUVWXYZ`
fi

if test -n "$ngx_feature_path"; then
    for ngx_temp in $ngx_feature_path; do
        ngx_feature_inc_path="$ngx_feature_inc_path -I $ngx_temp"
    done
fi

cat << END > $NGX_AUTOTEST.c

#include <sys/types.h>
$NGX_INCLUDE_UNISTD_H
$ngx_feature_incs

int main() {
    $ngx_feature_test;
    return 0;
}

END


ngx_test="$CC $CC_TEST_FLAGS $CC_AUX_FLAGS $ngx_feature_inc_path \
          -o $NGX_AUTOTEST $NGX_AUTOTEST.c $NGX_TEST_LD_OPT $ngx_feature_libs"

ngx_feature_inc_path=

eval "/bin/sh -c \"$ngx_test\" >> $NGX_AUTOCONF_ERR 2>&1"


if [ -x $NGX_AUTOTEST ]; then

    case "$ngx_feature_run" in

        yes)
            # /bin/sh is used to intercept "Killed" or "Abort trap" messages
            if /bin/sh -c $NGX_AUTOTEST >> $NGX_AUTOCONF_ERR 2>&1; then
                echo " found"
                ngx_found=yes

                if test -n "$ngx_feature_name"; then
                    have=$ngx_have_feature . auto/have
                fi

            else
                echo " found but is not working"
            fi
        ;;

        value)
            # /bin/sh is used to intercept "Killed" or "Abort trap" messages
            if /bin/sh -c $NGX_AUTOTEST >> $NGX_AUTOCONF_ERR 2>&1; then
                echo " found"
                ngx_found=yes

                cat << END >> $NGX_AUTO_CONFIG_H

#ifndef $ngx_feature_name
#define $ngx_feature_name  `$NGX_AUTOTEST`
#endif

END
            else
                echo " found but is not working"
            fi
        ;;

        bug)
            # /bin/sh is used to intercept "Killed" or "Abort trap" messages
            if /bin/sh -c $NGX_AUTOTEST >> $NGX_AUTOCONF_ERR 2>&1; then
                echo " not found"

            else
                echo " found"
                ngx_found=yes

                if test -n "$ngx_feature_name"; then
                    have=$ngx_have_feature . auto/have
                fi
            fi
        ;;

        *)
            echo " found"
            ngx_found=yes

            if test -n "$ngx_feature_name"; then
                have=$ngx_have_feature . auto/have
            fi
        ;;

    esac

else
    echo " not found"

    echo "----------"    >> $NGX_AUTOCONF_ERR
    cat $NGX_AUTOTEST.c  >> $NGX_AUTOCONF_ERR
    echo "----------"    >> $NGX_AUTOCONF_ERR
    echo $ngx_test       >> $NGX_AUTOCONF_ERR
    echo "----------"    >> $NGX_AUTOCONF_ERR
fi

rm -rf $NGX_AUTOTEST*