new file mode 100644
--- /dev/null
+++ b/src/event/modules/ngx_rtsig_module.c
@@ -0,0 +1,814 @@
+
+/*
+ * Copyright (C) Igor Sysoev
+ */
+
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+#include <ngx_event.h>
+
+
+#if (TEST_BUILD_RTSIG)
+
+#define F_SETSIG       10
+#define SIGRTMIN       33
+#define si_fd          __spare__[0]
+#define KERN_RTSIGNR   30
+#define KERN_RTSIGMAX  31
+
+int sigtimedwait(const sigset_t *set, siginfo_t *info,
+                 const struct timespec *timeout)
+{
+    return -1;
+}
+
+int ngx_linux_rtsig_max;
+
+#endif
+
+
+typedef struct {
+    int        signo;
+    ngx_int_t  overflow_events;
+    ngx_int_t  overflow_test;
+    ngx_int_t  overflow_threshold;
+} ngx_rtsig_conf_t;
+
+
+extern ngx_event_module_t  ngx_poll_module_ctx;
+
+static ngx_int_t ngx_rtsig_init(ngx_cycle_t *cycle);
+static void ngx_rtsig_done(ngx_cycle_t *cycle);
+static ngx_int_t ngx_rtsig_add_connection(ngx_connection_t *c);
+static ngx_int_t ngx_rtsig_del_connection(ngx_connection_t *c, u_int flags);
+static ngx_int_t ngx_rtsig_process_events(ngx_cycle_t *cycle);
+static ngx_int_t ngx_rtsig_process_overflow(ngx_cycle_t *cycle);
+
+static void *ngx_rtsig_create_conf(ngx_cycle_t *cycle);
+static char *ngx_rtsig_init_conf(ngx_cycle_t *cycle, void *conf);
+static char *ngx_check_ngx_overflow_threshold_bounds(ngx_conf_t *cf,
+                                                     void *post, void *data);
+
+
+static sigset_t        set;
+static ngx_uint_t      overflow, overflow_current;
+static struct pollfd  *overflow_list;
+
+
+static ngx_str_t      rtsig_name = ngx_string("rtsig");
+
+static ngx_conf_num_bounds_t  ngx_overflow_threshold_bounds = {
+    ngx_check_ngx_overflow_threshold_bounds, 2, 10
+};
+
+
+static ngx_command_t  ngx_rtsig_commands[] = {
+
+    {ngx_string("rtsig_signo"),
+     NGX_EVENT_CONF|NGX_CONF_TAKE1,
+     ngx_conf_set_num_slot,
+     0,
+     offsetof(ngx_rtsig_conf_t, signo),
+     NULL},
+
+    {ngx_string("rtsig_overflow_events"),
+     NGX_EVENT_CONF|NGX_CONF_TAKE1,
+     ngx_conf_set_num_slot,
+     0,
+     offsetof(ngx_rtsig_conf_t, overflow_events),
+     NULL},
+
+    {ngx_string("rtsig_overflow_test"),
+     NGX_EVENT_CONF|NGX_CONF_TAKE1,
+     ngx_conf_set_num_slot,
+     0,
+     offsetof(ngx_rtsig_conf_t, overflow_test),
+     NULL},
+
+    {ngx_string("rtsig_overflow_threshold"),
+     NGX_EVENT_CONF|NGX_CONF_TAKE1,
+     ngx_conf_set_num_slot,
+     0,
+     offsetof(ngx_rtsig_conf_t, overflow_threshold),
+     &ngx_overflow_threshold_bounds},
+
+    ngx_null_command
+};
+
+
+ngx_event_module_t  ngx_rtsig_module_ctx = {
+    &rtsig_name,
+    ngx_rtsig_create_conf,               /* create configuration */
+    ngx_rtsig_init_conf,                 /* init configuration */
+
+    {
+        NULL,                            /* add an event */
+        NULL,                            /* delete an event */
+        NULL,                            /* enable an event */
+        NULL,                            /* disable an event */
+        ngx_rtsig_add_connection,        /* add an connection */
+        ngx_rtsig_del_connection,        /* delete an connection */
+        NULL,                            /* process the changes */
+        ngx_rtsig_process_events,        /* process the events */
+        ngx_rtsig_init,                  /* init the events */
+        ngx_rtsig_done,                  /* done the events */
+    }
+
+};
+
+ngx_module_t  ngx_rtsig_module = {
+    NGX_MODULE,
+    &ngx_rtsig_module_ctx,               /* module context */
+    ngx_rtsig_commands,                  /* module directives */
+    NGX_EVENT_MODULE,                      /* module type */
+    NULL,                                  /* init module */
+    NULL                                   /* init process */
+};
+
+
+static ngx_int_t ngx_rtsig_init(ngx_cycle_t *cycle)
+{
+    ngx_rtsig_conf_t  *rtscf;
+
+    if (ngx_poll_module_ctx.actions.init(cycle) == NGX_ERROR) {
+        return NGX_ERROR;
+    }
+
+    rtscf = ngx_event_get_conf(cycle->conf_ctx, ngx_rtsig_module);
+
+    sigemptyset(&set);
+    sigaddset(&set, rtscf->signo);
+    sigaddset(&set, rtscf->signo + 1);
+    sigaddset(&set, SIGIO);
+
+    if (sigprocmask(SIG_BLOCK, &set, NULL) == -1) {
+        ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_errno,
+                      "sigprocmask() failed");
+        return NGX_ERROR;
+    }
+
+    if (overflow_list) {
+        ngx_free(overflow_list);
+    }
+
+    overflow_list = ngx_alloc(sizeof(struct pollfd) * rtscf->overflow_events,
+                              cycle->log);
+    if (overflow_list == NULL) {
+        return NGX_ERROR;
+    }
+
+    ngx_io = ngx_os_io;
+
+    ngx_event_actions = ngx_rtsig_module_ctx.actions;
+
+    ngx_event_flags = NGX_USE_RTSIG_EVENT|NGX_HAVE_GREEDY_EVENT;
+
+    return NGX_OK;
+}
+
+
+static void ngx_rtsig_done(ngx_cycle_t *cycle)
+{
+    ngx_poll_module_ctx.actions.done(cycle);
+}
+
+
+static ngx_int_t ngx_rtsig_add_connection(ngx_connection_t *c)
+{
+    int                signo;
+    ngx_rtsig_conf_t  *rtscf;
+
+    if (c->read->accept && c->read->disabled) {
+
+        ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0,
+                       "rtsig enable connection: fd:%d", c->fd);
+
+        if (fcntl(c->fd, F_SETOWN, ngx_pid) == -1) {
+            ngx_log_error(NGX_LOG_ALERT, c->log, ngx_errno,
+                          "fcntl(F_SETOWN) failed");
+            return NGX_ERROR;
+        }
+
+        c->read->active = 1;
+        c->read->disabled = 0;
+    }
+
+    rtscf = ngx_event_get_conf(ngx_cycle->conf_ctx, ngx_rtsig_module);
+
+    signo = rtscf->signo + c->read->instance;
+
+    ngx_log_debug2(NGX_LOG_DEBUG_EVENT, c->log, 0,
+                   "rtsig add connection: fd:%d signo:%d", c->fd, signo);
+
+    if (fcntl(c->fd, F_SETFL, O_RDWR|O_NONBLOCK|O_ASYNC) == -1) {
+        ngx_log_error(NGX_LOG_ALERT, c->log, ngx_errno,
+                      "fcntl(O_RDWR|O_NONBLOCK|O_ASYNC) failed");
+        return NGX_ERROR;
+    }
+
+    if (fcntl(c->fd, F_SETSIG, signo) == -1) {
+        ngx_log_error(NGX_LOG_ALERT, c->log, ngx_errno,
+                      "fcntl(F_SETSIG) failed");
+        return NGX_ERROR;
+    }
+
+    if (fcntl(c->fd, F_SETOWN, ngx_pid) == -1) {
+        ngx_log_error(NGX_LOG_ALERT, c->log, ngx_errno,
+                      "fcntl(F_SETOWN) failed");
+        return NGX_ERROR;
+    }
+
+#if (HAVE_ONESIGFD)
+    if (fcntl(c->fd, F_SETAUXFL, O_ONESIGFD) == -1) {
+        ngx_log_error(NGX_LOG_ALERT, c->log, ngx_errno,
+                      "fcntl(F_SETAUXFL) failed");
+        return NGX_ERROR;
+    }
+#endif
+
+    c->read->active = 1;
+    c->write->active = 1;
+
+    return NGX_OK;
+}
+
+
+static ngx_int_t ngx_rtsig_del_connection(ngx_connection_t *c, u_int flags)
+{
+    ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0,
+                   "rtsig del connection: fd:%d", c->fd);
+
+    if ((flags & NGX_DISABLE_EVENT) && c->read->accept) {
+
+        ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0,
+                       "rtsig disable connection: fd:%d", c->fd);
+
+        c->read->active = 0;
+        c->read->disabled = 1;
+        return NGX_OK;
+    }
+
+    if (flags & NGX_CLOSE_EVENT) {
+        c->read->active = 0;
+        c->write->active = 0;
+        return NGX_OK;
+    }
+
+    if (fcntl(c->fd, F_SETFL, O_RDWR|O_NONBLOCK) == -1) {
+        ngx_log_error(NGX_LOG_ALERT, c->log, ngx_errno,
+                      "fcntl(O_RDWR|O_NONBLOCK) failed");
+        return NGX_ERROR;
+    }
+
+    c->read->active = 0;
+    c->write->active = 0;
+
+    return NGX_OK;
+}
+
+
+ngx_int_t ngx_rtsig_process_events(ngx_cycle_t *cycle)
+{
+    int                 signo;
+    ngx_int_t           instance, i;
+    ngx_uint_t          expire;
+    size_t              n;
+    ngx_msec_t          timer;
+    ngx_err_t           err;
+    siginfo_t           si;
+    ngx_event_t        *rev, *wev;
+    struct timeval      tv;
+    struct timespec     ts, *tp;
+    struct sigaction    sa;
+    ngx_epoch_msec_t    delta;
+    ngx_connection_t   *c;
+    ngx_rtsig_conf_t   *rtscf;
+
+    if (overflow) {
+        timer = 0;
+        expire = 0;
+
+    } else {
+        for ( ;; ) {
+            timer = ngx_event_find_timer();
+
+#if (NGX_THREADS)
+
+            if (timer == NGX_TIMER_ERROR) {
+                return NGX_ERROR;
+            }
+
+            if (timer == NGX_TIMER_INFINITE || timer > 500) {
+                timer = 500;
+                break;
+            }
+
+#endif
+
+            if (timer != 0) {
+                break;
+            }
+
+            ngx_log_debug0(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
+                           "rtsig expired timer");
+
+            ngx_event_expire_timers((ngx_msec_t)
+                                    (ngx_elapsed_msec - ngx_old_elapsed_msec));
+
+            if (ngx_posted_events && ngx_threaded) {
+                ngx_wakeup_worker_thread(cycle);
+            }
+        }
+
+        expire = 1;
+
+        if (ngx_accept_mutex) {
+            if (ngx_accept_disabled > 0) {
+                ngx_accept_disabled--;
+
+            } else {
+                ngx_accept_mutex_held = 0;
+
+                if (ngx_trylock_accept_mutex(cycle) == NGX_ERROR) {
+                    return NGX_ERROR;
+                }
+
+                if (ngx_accept_mutex_held == 0
+                    && (timer == NGX_TIMER_INFINITE
+                        || timer > ngx_accept_mutex_delay))
+                {
+                    timer = ngx_accept_mutex_delay;
+                    expire = 0;
+                } 
+            }
+        }
+    }
+
+    if (timer == NGX_TIMER_INFINITE) {
+        tp = NULL;
+        expire = 0;
+
+    } else {
+        ts.tv_sec = timer / 1000;
+        ts.tv_nsec = (timer % 1000) * 1000000;
+        tp = &ts;
+    }
+
+    ngx_old_elapsed_msec = ngx_elapsed_msec;
+
+    ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
+                   "rtsig timer: %d", timer);
+
+    /* Linux's sigwaitinfo() is sigtimedwait() with the NULL timeout pointer */
+
+    signo = sigtimedwait(&set, &si, tp);
+
+    if (signo == -1) {
+        err = ngx_errno;
+
+        ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, err,
+                       "rtsig signo:%d", signo);
+
+        if (err == NGX_EAGAIN) {
+
+            if (timer == NGX_TIMER_INFINITE) {
+                ngx_accept_mutex_unlock();
+                ngx_log_error(NGX_LOG_ALERT, cycle->log, err,
+                              "sigtimedwait() returned EAGAIN without timeout");
+                return NGX_ERROR;
+            }
+
+            err = 0;
+        }
+
+    } else {
+        err = 0;
+        ngx_log_debug3(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
+                       "rtsig signo:%d fd:%d band:%X",
+                       signo, si.si_fd, si.si_band);
+    }
+
+    ngx_gettimeofday(&tv);
+    ngx_time_update(tv.tv_sec);
+
+    delta = ngx_elapsed_msec;
+    ngx_elapsed_msec = (ngx_epoch_msec_t) tv.tv_sec * 1000
+                                          + tv.tv_usec / 1000 - ngx_start_msec;
+
+    if (err) {
+        ngx_accept_mutex_unlock();
+        ngx_log_error((err == NGX_EINTR) ? NGX_LOG_INFO : NGX_LOG_ALERT,
+                      cycle->log, err, "sigtimedwait() failed");
+        return NGX_ERROR;
+    }
+
+    if (timer != NGX_TIMER_INFINITE) {
+        delta = ngx_elapsed_msec - delta;
+
+        ngx_log_debug2(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
+                       "rtsig timer: %d, delta: %d", timer, (int) delta);
+    }
+
+    rtscf = ngx_event_get_conf(ngx_cycle->conf_ctx, ngx_rtsig_module);
+
+    if (signo == rtscf->signo || signo == rtscf->signo + 1) {
+
+        if (overflow && (ngx_uint_t) si.si_fd > overflow_current) {
+            return NGX_OK;
+        }
+
+        /* TODO: old_cycles */
+
+        c = &ngx_cycle->connections[si.si_fd];
+
+        instance = signo - rtscf->signo;
+
+        rev = c->read;
+
+        if (c->read->instance != instance) {
+
+            /*
+             * the stale event from a file descriptor
+             * that was just closed in this iteration
+             */
+
+            ngx_accept_mutex_unlock();
+
+            ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
+                           "rtsig: stale event " PTR_FMT, c);
+
+            return NGX_OK;
+        }
+
+        if (si.si_band & (POLLIN|POLLHUP|POLLERR)) {
+            if (rev->active) {
+
+                if (ngx_threaded && !rev->accept) {
+                    if (ngx_mutex_lock(ngx_posted_events_mutex) == NGX_ERROR) {
+                        ngx_accept_mutex_unlock();
+                        return NGX_ERROR;
+                    }
+
+                    rev->posted_ready = 1;
+                    ngx_post_event(rev);
+
+                    ngx_mutex_unlock(ngx_posted_events_mutex);
+
+                } else {
+                    rev->ready = 1;
+
+                    if (!ngx_threaded && !ngx_accept_mutex_held) {
+                        rev->event_handler(rev);
+
+                    } else if (rev->accept) {
+                        if (ngx_accept_disabled <= 0) {
+                            rev->event_handler(rev);
+                        }
+
+                    } else {
+                        ngx_post_event(rev); 
+                    }
+                }
+            }
+        }
+
+        wev = c->write;
+
+        if (si.si_band & (POLLOUT|POLLHUP|POLLERR)) {
+            if (wev->active) {
+
+                if (ngx_threaded) {
+                    if (ngx_mutex_lock(ngx_posted_events_mutex) == NGX_ERROR) {
+                        ngx_accept_mutex_unlock();
+                        return NGX_ERROR;
+                    }
+
+                    wev->posted_ready = 1;
+                    ngx_post_event(wev);
+
+                    ngx_mutex_unlock(ngx_posted_events_mutex);
+
+                } else {
+                    wev->ready = 1;
+
+                    if (!ngx_threaded && !ngx_accept_mutex_held) {
+                        wev->event_handler(wev);
+
+                    } else {
+                        ngx_post_event(wev);
+                    }
+                }
+            }
+        }
+
+    } else if (signo == SIGIO) {
+        ngx_accept_mutex_unlock();
+
+        ngx_log_error(NGX_LOG_ALERT, cycle->log, 0,
+                      "rt signal queue overflowed");
+
+        /* flush the RT signal queue */
+
+        ngx_memzero(&sa, sizeof(struct sigaction));
+        sa.sa_handler = SIG_DFL;
+        sigemptyset(&sa.sa_mask);
+
+        if (sigaction(rtscf->signo, &sa, NULL) == -1) {
+            ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
+                          "sigaction(%d, SIG_DFL) failed", rtscf->signo);
+        }
+
+        if (sigaction(rtscf->signo + 1, &sa, NULL) == -1) {
+            ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
+                          "sigaction(%d, SIG_DFL) failed", rtscf->signo + 1);
+        }
+
+        overflow = 1;
+        overflow_current = 0;
+        ngx_event_actions.process_events = ngx_rtsig_process_overflow;
+
+        return NGX_ERROR;
+
+    } else if (signo != -1) {
+        ngx_accept_mutex_unlock();
+
+        ngx_log_error(NGX_LOG_ALERT, cycle->log, 0,
+                      "sigtimedwait() returned unexpected signal: %d", signo);
+
+        return NGX_ERROR;
+    }
+
+    ngx_accept_mutex_unlock();
+
+    if (expire && delta) {
+        ngx_event_expire_timers((ngx_msec_t) delta);
+    }
+
+    if (ngx_posted_events) {
+        if (ngx_threaded) {
+            ngx_wakeup_worker_thread(cycle);
+
+        } else {
+            ngx_event_process_posted(cycle);
+        }
+    }
+
+    if (signo == -1) {
+        return NGX_AGAIN;
+    } else {
+        return NGX_OK;
+    }
+}
+
+
+/* TODO: old cylces */
+
+static ngx_int_t ngx_rtsig_process_overflow(ngx_cycle_t *cycle)
+{
+    int                name[2], rtsig_max, rtsig_nr, events, ready;
+    size_t             len;
+    ngx_int_t          tested, n, i;
+    ngx_err_t          err;
+    ngx_event_t       *rev, *wev;
+    ngx_connection_t  *c;
+    ngx_rtsig_conf_t  *rtscf;
+
+    rtscf = ngx_event_get_conf(ngx_cycle->conf_ctx, ngx_rtsig_module);
+
+    tested = 0;
+
+    for ( ;; ) {
+
+        n = 0;
+        while (n < rtscf->overflow_events) {
+
+            if (overflow_current == cycle->connection_n) {
+                break;
+            }
+
+            c = &cycle->connections[overflow_current++];
+
+            if (c->fd == -1) {
+                continue;
+            }
+
+            events = 0;
+
+            if (c->read->active && c->read->event_handler) {
+                events |= POLLIN;
+            }
+
+            if (c->write->active && c->write->event_handler) {
+                events |= POLLOUT;
+            }
+
+            if (events == 0) {
+                continue;
+            }
+
+            overflow_list[n].fd = c->fd;
+            overflow_list[n].events = events;
+            overflow_list[n].revents = 0;
+            n++;
+        }
+
+        if (n == 0) {
+            break;
+        }
+
+        for ( ;; ) {
+            ready = poll(overflow_list, n, 0);
+
+            if (ready == -1) {
+                err = ngx_errno;
+                ngx_log_error((err == NGX_EINTR) ? NGX_LOG_INFO : NGX_LOG_ALERT,
+                              cycle->log, 0,
+                              "poll() failed while the overflow recover");
+
+                if (err == NGX_EINTR) {
+                    continue;
+                }
+            }
+
+            break;
+        }
+
+        if (ready <= 0) {
+            continue;
+        }
+
+        if (ngx_mutex_lock(ngx_posted_events_mutex) == NGX_ERROR) {
+            return NGX_ERROR;
+        }
+
+        for (i = 0; i < n; i++) {
+            c = &cycle->connections[overflow_list[i].fd];
+
+            rev = c->read;
+
+            if (rev->active
+                && !rev->closed
+                && rev->event_handler
+                && (overflow_list[i].revents
+                                          & (POLLIN|POLLERR|POLLHUP|POLLNVAL)))
+            {
+                tested++;
+
+                if (ngx_threaded) {
+                    rev->posted_ready = 1;
+                    ngx_post_event(rev);
+
+                } else {
+                    rev->ready = 1;
+                    rev->event_handler(rev); 
+                }
+            }
+
+            wev = c->write;
+
+            if (wev->active
+                && !wev->closed
+                && wev->event_handler
+                && (overflow_list[i].revents
+                                         & (POLLOUT|POLLERR|POLLHUP|POLLNVAL)))
+            {
+                tested++;
+
+                if (ngx_threaded) {
+                    wev->posted_ready = 1;
+                    ngx_post_event(wev);
+
+                } else {
+                    wev->ready = 1;
+                    wev->event_handler(wev); 
+                }
+            }
+        }
+
+        ngx_mutex_unlock(ngx_posted_events_mutex);
+
+        if (tested >= rtscf->overflow_test) {
+
+            if (ngx_linux_rtsig_max) {
+
+                /*
+                 * Check the current rt queue length to prevent
+                 * the new overflow.
+                 *
+                 * Learn the /proc/sys/kernel/rtsig-max value because
+                 * it can be changed sisnce the last checking.
+                 */
+
+                name[0] = CTL_KERN;
+                name[1] = KERN_RTSIGMAX;
+                len = sizeof(rtsig_max);
+                if (sysctl(name, sizeof(name), &rtsig_max, &len, NULL, 0) == -1)
+                {
+                    ngx_log_error(NGX_LOG_ALERT, cycle->log, errno,
+                                  "sysctl(KERN_RTSIGMAX) failed");
+                    return NGX_ERROR;
+                }
+
+                name[0] = CTL_KERN;
+                name[1] = KERN_RTSIGNR;
+                len = sizeof(rtsig_nr);
+                if (sysctl(name, sizeof(name), &rtsig_nr, &len, NULL, 0) == -1)
+                {
+                    ngx_log_error(NGX_LOG_ALERT, cycle->log, errno,
+                                  "sysctl(KERN_RTSIGNR) failed");
+                    return NGX_ERROR;
+                }
+
+                /*
+                 * drain the rt signal queue if the /proc/sys/kernel/rtsig-nr
+                 * is bigger than
+                 *    /proc/sys/kernel/rtsig-max / rtsig_overflow_threshold
+                 */
+
+                if (rtsig_max / rtscf->overflow_threshold < rtsig_nr) {
+                    ngx_log_debug2(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
+                                   "rtsig queue state: %d/%d",
+                                   rtsig_nr, rtsig_max);
+                    while (ngx_rtsig_process_events(cycle) == NGX_OK) {
+                        /* void */
+                    }
+                }
+
+            } else {
+
+                /*
+                 * Linux has not KERN_RTSIGMAX since 2.6.6-mm2
+                 * so drain the rt signal queue unconditionally
+                 */
+
+                while (ngx_rtsig_process_events(cycle) == NGX_OK) { /* void */ }
+            }
+
+            tested = 0;
+        }
+    }
+
+    if (ngx_posted_events) {
+        if (ngx_threaded) {
+            ngx_wakeup_worker_thread(cycle);
+
+        } else {
+            ngx_event_process_posted(cycle);
+        }
+    }
+
+    ngx_log_error(NGX_LOG_INFO, cycle->log, 0,
+                  "rt signal queue overflow recovered");
+
+    overflow = 0;
+    ngx_event_actions.process_events = ngx_rtsig_process_events;
+
+    return NGX_OK;
+}
+
+
+static void *ngx_rtsig_create_conf(ngx_cycle_t *cycle)
+{
+    ngx_rtsig_conf_t  *rtscf;
+
+    ngx_test_null(rtscf, ngx_palloc(cycle->pool, sizeof(ngx_rtsig_conf_t)),
+                  NGX_CONF_ERROR);
+
+    rtscf->signo = NGX_CONF_UNSET;
+    rtscf->overflow_events = NGX_CONF_UNSET;
+    rtscf->overflow_test = NGX_CONF_UNSET;
+    rtscf->overflow_threshold = NGX_CONF_UNSET;
+
+    return rtscf;
+}
+
+
+static char *ngx_rtsig_init_conf(ngx_cycle_t *cycle, void *conf)
+{
+    ngx_rtsig_conf_t  *rtscf = conf;
+
+    /* LinuxThreads use the first 3 RT signals */
+    ngx_conf_init_value(rtscf->signo, SIGRTMIN + 10);
+
+    ngx_conf_init_value(rtscf->overflow_events, 16);
+    ngx_conf_init_value(rtscf->overflow_test, 32);
+    ngx_conf_init_value(rtscf->overflow_threshold, 10);
+
+    return NGX_CONF_OK;
+}
+
+
+static char *ngx_check_ngx_overflow_threshold_bounds(ngx_conf_t *cf,
+                                                     void *post, void *data)
+{
+    if (ngx_linux_rtsig_max) {
+        return ngx_conf_check_num_bounds(cf, post, data);
+    }
+
+    ngx_conf_log_error(NGX_LOG_WARN, cf, 0,
+                       "\"rtsig_overflow_threshold\" is not supported "
+                       "since Linux 2.6.6-mm2, ignored");
+
+    return NGX_CONF_OK;
+}