Commit 8fda0db5 authored by Yann Ylavic's avatar Yann Ylavic
Browse files

event: better apr_pollset_add() failure handling to avoid an (very unlikely) 

worker vs listener race condition.



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1809273 13f79535-47bb-0310-9956-ffa450edef68
parent 33539b95

server/mpm/event/event.c

+12 −14
Original line number Diff line number Diff line
@@ -315,6 +315,7 @@ static void TO_QUEUE_APPEND(struct timeout_queue *q, event_conn_state_t *el) 
static void TO_QUEUE_REMOVE(struct timeout_queue *q, event_conn_state_t *el)

{

    APR_RING_REMOVE(el, timeout_list);

    APR_RING_ELEM_INIT(el, timeout_list);

    apr_atomic_dec32(q->total);

    --q->count;

}
@@ -837,17 +838,16 @@ static int start_lingering_close_blocking(event_conn_state_t *cs) 
    apr_thread_mutex_lock(timeout_mutex);

    TO_QUEUE_APPEND(q, cs);

    rv = apr_pollset_add(event_pollset, &cs->pfd);

    apr_thread_mutex_unlock(timeout_mutex);

    if (rv != APR_SUCCESS && !APR_STATUS_IS_EEXIST(rv)) {

        ap_log_error(APLOG_MARK, APLOG_ERR, rv, ap_server_conf, APLOGNO(03092)

                     "start_lingering_close: apr_pollset_add failure");

        apr_thread_mutex_lock(timeout_mutex);

        TO_QUEUE_REMOVE(q, cs);

        apr_thread_mutex_unlock(timeout_mutex);

        ap_log_error(APLOG_MARK, APLOG_ERR, rv, ap_server_conf, APLOGNO(03092)

                     "start_lingering_close: apr_pollset_add failure");

        apr_socket_close(cs->pfd.desc.s);

        ap_push_pool(worker_queue_info, cs->p);

        return 0;

    }

    apr_thread_mutex_unlock(timeout_mutex);

    return 1;

}
@@ -1088,17 +1088,18 @@ read_request: 
            apr_thread_mutex_lock(timeout_mutex);

            TO_QUEUE_APPEND(cs->sc->wc_q, cs);

            rc = apr_pollset_add(event_pollset, &cs->pfd);

            apr_thread_mutex_unlock(timeout_mutex);

            if (rc != APR_SUCCESS && !APR_STATUS_IS_EEXIST(rc)) {

                TO_QUEUE_REMOVE(cs->sc->wc_q, cs);

                apr_thread_mutex_unlock(timeout_mutex);

                ap_log_error(APLOG_MARK, APLOG_ERR, rc, ap_server_conf, APLOGNO(03465)

                             "process_socket: apr_pollset_add failure for "

                             "write completion");

                apr_thread_mutex_lock(timeout_mutex);

                TO_QUEUE_REMOVE(cs->sc->wc_q, cs);

                apr_thread_mutex_unlock(timeout_mutex);

                apr_socket_close(cs->pfd.desc.s);

                ap_push_pool(worker_queue_info, cs->p);

            }

            else {

                apr_thread_mutex_unlock(timeout_mutex);

            }

            return;

        }

        else if (c->keepalive != AP_CONN_KEEPALIVE || c->aborted ||
@@ -1136,18 +1137,17 @@ read_request: 
        apr_thread_mutex_lock(timeout_mutex);

        TO_QUEUE_APPEND(cs->sc->ka_q, cs);

        rc = apr_pollset_add(event_pollset, &cs->pfd);

        apr_thread_mutex_unlock(timeout_mutex);

        if (rc != APR_SUCCESS && !APR_STATUS_IS_EEXIST(rc)) {

            TO_QUEUE_REMOVE(cs->sc->ka_q, cs);

            apr_thread_mutex_unlock(timeout_mutex);

            ap_log_error(APLOG_MARK, APLOG_ERR, rc, ap_server_conf, APLOGNO(03093)

                         "process_socket: apr_pollset_add failure for "

                         "keep alive");

            apr_thread_mutex_lock(timeout_mutex);

            TO_QUEUE_REMOVE(cs->sc->ka_q, cs);

            apr_thread_mutex_unlock(timeout_mutex);

            apr_socket_close(cs->pfd.desc.s);

            ap_push_pool(worker_queue_info, cs->p);

            return;

        }

        apr_thread_mutex_unlock(timeout_mutex);

    }

    else if (cs->pub.state == CONN_STATE_SUSPENDED) {

        cs->c->suspended_baton = cs;
@@ -1600,7 +1600,6 @@ static void process_lingering_close(event_conn_state_t *cs, const apr_pollfd_t * 
    rv = apr_pollset_remove(event_pollset, pfd);

    apr_thread_mutex_unlock(timeout_mutex);

    AP_DEBUG_ASSERT(rv == APR_SUCCESS ||  APR_STATUS_IS_NOTFOUND(rv));

    TO_QUEUE_ELEM_INIT(cs);



    rv = apr_socket_close(csd);

    AP_DEBUG_ASSERT(rv == APR_SUCCESS);
@@ -1902,7 +1901,6 @@ static void * APR_THREAD_FUNC listener_thread(apr_thread_t * thd, void *dummy) 
                    TO_QUEUE_REMOVE(remove_from_q, cs);

                    rc = apr_pollset_remove(event_pollset, &cs->pfd);

                    apr_thread_mutex_unlock(timeout_mutex);

                    TO_QUEUE_ELEM_INIT(cs);



                    /*

                     * Some of the pollset backends, like KQueue or Epoll