BUG/MEDIUM: server: support changing the slowstart value from state-file

If the slowstart value in a state file implies the latest state change
is within the slowstart period, we end up calling srv_update_status()
to reschedule the server's state change but its task is not yet
allocated and remains null, causing a crash on startup.

Make sure srv_update_status() supports being called with partially
initialized servers which do not yet have a task. If the task has to
be scheduled, it will necessarily happen after initialization since
it will result from a state change.

This should be backported wherever server-state is present.

diff --git a/src/server.c b/src/server.c
index 45b0f41216771ae3d89d48a8dcac2223c939362c..2271f9e9969e73abd20358a8316bd6d9cedcb5c9 100644 (file)
--- a/src/server.c
+++ b/src/server.c
@@ -4630,7 +4630,9 @@ INITCALL1(STG_REGISTER, cli_register_kw, &cli_kws);
  * This function applies server's status changes, it is
  * is designed to be called asynchronously.
  *
- * Must be called with the server lock held.
+ * Must be called with the server lock held. This may also be called at init
+ * time as the result of parsing the state file, in which case no lock will be
+ * held, and the server's warmup task can be null.
  */
 static void srv_update_status(struct server *s)
 {
@@ -4730,7 +4732,7 @@ static void srv_update_status(struct server *s)
                                s->down_time += now.tv_sec - s->last_change;
 
                        s->last_change = now.tv_sec;
-                       if (s->next_state == SRV_ST_STARTING)
+                       if (s->next_state == SRV_ST_STARTING && s->warmup)
                                task_schedule(s->warmup, tick_add(now_ms, MS_TO_TICKS(MAX(1000, s->slowstart / 20))));
 
                        server_recalc_eweight(s, 0);
@@ -4908,8 +4910,10 @@ static void srv_update_status(struct server *s)
                        }
                        else {
                                s->next_state = SRV_ST_STARTING;
-                               if (s->slowstart > 0)
-                                       task_schedule(s->warmup, tick_add(now_ms, MS_TO_TICKS(MAX(1000, s->slowstart / 20))));
+                               if (s->slowstart > 0) {
+                                       if (s->warmup)
+                                               task_schedule(s->warmup, tick_add(now_ms, MS_TO_TICKS(MAX(1000, s->slowstart / 20))));
+                               }
                                else
                                        s->next_state = SRV_ST_RUNNING;
                        }