From 0c1fbfaf77d6f7b2a6628deaf309bbe1c3e7a8e8 Mon Sep 17 00:00:00 2001

From: William Brown <firstyear@redhat.com>

Date: Tue, 28 Nov 2017 13:39:19 +0100

Subject: [PATCH] Ticket 48184 - close connections at shutdown cleanly.

Bug Description:  During shutdown we would not close connections.

In the past this may have just been an annoyance, but now with the way

nunc-stans works, io events can still trigger on open xeisting connectinos

during shutdown.

Fix Description:  Close connections during shutdown rather than

leaving them alive.

https://pagure.io/389-ds-base/issue/48184

Author: wibrown

Review by: lkrispen, vashirov (Thank you!)

---

 ldap/servers/slapd/conntable.c | 13 +++++++

 ldap/servers/slapd/daemon.c    | 77 ++++++++++++++++++++++++++----------------

 ldap/servers/slapd/fe.h        |  1 +

 ldap/servers/slapd/slap.h      |  1 +

 4 files changed, 63 insertions(+), 29 deletions(-)

diff --git a/ldap/servers/slapd/conntable.c b/ldap/servers/slapd/conntable.c

index 7c57b47cd..f2f763dfa 100644

--- a/ldap/servers/slapd/conntable.c

+++ b/ldap/servers/slapd/conntable.c

@@ -91,6 +91,19 @@ connection_table_abandon_all_operations(Connection_Table *ct)

     }

 }

+void

+connection_table_disconnect_all(Connection_Table *ct)

+{

+    for (size_t i = 0; i < ct->size; i++) {

+        if (ct->c[i].c_mutex) {

+            Connection *c = &(ct->c[i]);

+            PR_EnterMonitor(c->c_mutex);

+            disconnect_server_nomutex(c, c->c_connid, -1, SLAPD_DISCONNECT_ABORT, ECANCELED);

+            PR_ExitMonitor(c->c_mutex);

+        }

+    }

+}

+

 /* Given a file descriptor for a socket, this function will return

  * a slot in the connection table to use.

  *

diff --git a/ldap/servers/slapd/daemon.c b/ldap/servers/slapd/daemon.c

index 4e0466ab3..c245a4d4e 100644

--- a/ldap/servers/slapd/daemon.c

+++ b/ldap/servers/slapd/daemon.c

@@ -1176,6 +1176,30 @@ slapd_daemon(daemon_ports_t *ports, ns_thrpool_t *tp)

     housekeeping_stop(); /* Run this after op_thread_cleanup() logged sth */

     disk_monitoring_stop();

+    /*

+     * Now that they are abandonded, we need to mark them as done.

+     * In NS while it's safe to allow excess jobs to be cleaned by

+     * by the walk and ns_job_done of remaining queued events, the

+     * issue is that if we allow something to live past this point

+     * the CT is freed from underneath, and bad things happen (tm).

+     *

+     * NOTE: We do this after we stop psearch, because there could

+     * be a race between flagging the psearch done, and users still

+     * try to send on the connection. Similar with op_threads.

+     */

+    connection_table_disconnect_all(the_connection_table);

+

+    /*

+     * WARNING: Normally we should close the tp in main

+     * but because of issues in the current connection design

+     * we need to close it here to guarantee events won't fire!

+     *

+     * All the connection close jobs "should" complete before

+     * shutdown at least.

+     */

+    ns_thrpool_shutdown(tp);

+    ns_thrpool_wait(tp);

+

     threads = g_get_active_threadcnt();

     if (threads > 0) {

         slapi_log_err(SLAPI_LOG_INFO, "slapd_daemon",

@@ -1628,23 +1652,18 @@ ns_handle_closure(struct ns_job_t *job)

     Connection *c = (Connection *)ns_job_get_data(job);

     int do_yield = 0;

-/* this function must be called from the event loop thread */

-#ifdef DEBUG

-    PR_ASSERT(0 == NS_JOB_IS_THREAD(ns_job_get_type(job)));

-#else

-    /* This doesn't actually confirm it's in the event loop thread, but it's a start */

-    if (NS_JOB_IS_THREAD(ns_job_get_type(job)) != 0) {

-        slapi_log_err(SLAPI_LOG_ERR, "ns_handle_closure", "Attempt to close outside of event loop thread %" PRIu64 " for fd=%d\n",

-                      c->c_connid, c->c_sd);

-        return;

-    }

-#endif

     PR_EnterMonitor(c->c_mutex);

+    /* Assert we really have the right job state. */

+    PR_ASSERT(job == c->c_job);

+

     connection_release_nolock_ext(c, 1); /* release ref acquired for event framework */

     PR_ASSERT(c->c_ns_close_jobs == 1);  /* should be exactly 1 active close job - this one */

     c->c_ns_close_jobs--;                /* this job is processing closure */

+    /* Because handle closure will add a new job, we need to detach our current one. */

+    c->c_job = NULL;

     do_yield = ns_handle_closure_nomutex(c);

     PR_ExitMonitor(c->c_mutex);

+    /* Remove this task now. */

     ns_job_done(job);

     if (do_yield) {

         /* closure not done - another reference still outstanding */

@@ -1667,6 +1686,14 @@ ns_connection_post_io_or_closing(Connection *conn)

         return;

     }

+    /*

+     * Cancel any existing ns jobs we have registered.

+     */

+    if (conn->c_job != NULL) {

+        ns_job_done(conn->c_job);

+        conn->c_job = NULL;

+    }

+

     if (CONN_NEEDS_CLOSING(conn)) {

         /* there should only ever be 0 or 1 active closure jobs */

         PR_ASSERT((conn->c_ns_close_jobs == 0) || (conn->c_ns_close_jobs == 1));

@@ -1676,13 +1703,10 @@ ns_connection_post_io_or_closing(Connection *conn)

                           conn->c_connid, conn->c_sd);

             return;

         } else {

-            /* just make sure we schedule the event to be closed in a timely manner */

-            tv.tv_sec = 0;

-            tv.tv_usec = slapd_wakeup_timer * 1000;

             conn->c_ns_close_jobs++;                                                      /* now 1 active closure job */

             connection_acquire_nolock_ext(conn, 1 /* allow acquire even when closing */); /* event framework now has a reference */

-            ns_result_t job_result = ns_add_timeout_job(conn->c_tp, &tv, NS_JOB_TIMER,

-                                                        ns_handle_closure, conn, NULL);

+            /* Close the job asynchronously. Why? */

+            ns_result_t job_result = ns_add_job(conn->c_tp, NS_JOB_TIMER, ns_handle_closure, conn, &(conn->c_job));

             if (job_result != NS_SUCCESS) {

                 if (job_result == NS_SHUTDOWN) {

                     slapi_log_err(SLAPI_LOG_INFO, "ns_connection_post_io_or_closing", "post closure job "

@@ -1726,7 +1750,7 @@ ns_connection_post_io_or_closing(Connection *conn)

 #endif

         ns_result_t job_result = ns_add_io_timeout_job(conn->c_tp, conn->c_prfd, &tv,

                                                        NS_JOB_READ | NS_JOB_PRESERVE_FD,

-                                                       ns_handle_pr_read_ready, conn, NULL);

+                                                       ns_handle_pr_read_ready, conn, &(conn->c_job));

         if (job_result != NS_SUCCESS) {

             if (job_result == NS_SHUTDOWN) {

                 slapi_log_err(SLAPI_LOG_INFO, "ns_connection_post_io_or_closing", "post I/O job for "

@@ -1755,19 +1779,13 @@ ns_handle_pr_read_ready(struct ns_job_t *job)

     int maxthreads = config_get_maxthreadsperconn();

     Connection *c = (Connection *)ns_job_get_data(job);

-/* this function must be called from the event loop thread */

-#ifdef DEBUG

-    PR_ASSERT(0 == NS_JOB_IS_THREAD(ns_job_get_type(job)));

-#else

-    /* This doesn't actually confirm it's in the event loop thread, but it's a start */

-    if (NS_JOB_IS_THREAD(ns_job_get_type(job)) != 0) {

-        slapi_log_err(SLAPI_LOG_ERR, "ns_handle_pr_read_ready", "Attempt to handle read ready outside of event loop thread %" PRIu64 " for fd=%d\n",

-                      c->c_connid, c->c_sd);

-        return;

-    }

-#endif

-

     PR_EnterMonitor(c->c_mutex);

+    /* Assert we really have the right job state. */

+    PR_ASSERT(job == c->c_job);

+

+    /* On all code paths we remove the job, so set it null now */

+    c->c_job = NULL;

+

     slapi_log_err(SLAPI_LOG_CONNS, "ns_handle_pr_read_ready", "activity on conn %" PRIu64 " for fd=%d\n",

                   c->c_connid, c->c_sd);

     /* if we were called due to some i/o event, see what the state of the socket is */

@@ -1826,6 +1844,7 @@ ns_handle_pr_read_ready(struct ns_job_t *job)

         slapi_log_err(SLAPI_LOG_CONNS, "ns_handle_pr_read_ready", "queued conn %" PRIu64 " for fd=%d\n",

                       c->c_connid, c->c_sd);

     }

+    /* Since we call done on the job, we need to remove it here. */

     PR_ExitMonitor(c->c_mutex);

     ns_job_done(job);

     return;

diff --git a/ldap/servers/slapd/fe.h b/ldap/servers/slapd/fe.h

index 4d25a9fb8..f47bb6145 100644

--- a/ldap/servers/slapd/fe.h

+++ b/ldap/servers/slapd/fe.h

@@ -100,6 +100,7 @@ extern Connection_Table *the_connection_table; /* JCM - Exported from globals.c

 Connection_Table *connection_table_new(int table_size);

 void connection_table_free(Connection_Table *ct);

 void connection_table_abandon_all_operations(Connection_Table *ct);

+void connection_table_disconnect_all(Connection_Table *ct);

 Connection *connection_table_get_connection(Connection_Table *ct, int sd);

 int connection_table_move_connection_out_of_active_list(Connection_Table *ct, Connection *c);

 void connection_table_move_connection_on_to_active_list(Connection_Table *ct, Connection *c);

diff --git a/ldap/servers/slapd/slap.h b/ldap/servers/slapd/slap.h

index 830944f72..08754d8fb 100644

--- a/ldap/servers/slapd/slap.h

+++ b/ldap/servers/slapd/slap.h

@@ -1644,6 +1644,7 @@ typedef struct conn

     void *c_io_layer_cb_data;            /* callback data */

     struct connection_table *c_ct;       /* connection table that this connection belongs to */

     ns_thrpool_t *c_tp;                  /* thread pool for this connection */

+    struct ns_job_t *c_job;                     /* If it exists, the current ns_job_t */

     int c_ns_close_jobs;                 /* number of current close jobs */

     char *c_ipaddr;                      /* ip address str - used by monitor */

 } Connection;

-- 

2.13.6