fix(persist): zero nresvals_to_sched after free_name_val_list

Crash: encode_NameValue_list called with count=21, s=NULL on worker
rejoin, causing SIGSEGV in persist_worker_hook_fun.

Root cause: free_name_val_list(xce_name_val_t***, int) accepted count by
value. It zeroed *vals (resvals_to_sched = NULL) but could not zero
nresvals_to_sched. Any caller that freed the scheduler resource snapshot
(opget.c workerlist, reply.c clusterconf, dataex.c, sched.c dispatch)
left nresvals_to_sched stale. When the worker later rejoined and the
WAL HOOK fired, the WAL encoder read count=21 with a NULL pointer.

Fix: change signature to free_name_val_list(xce_name_val_t***, int*)
so both fields are zeroed atomically. Update all 7 call sites.

src/controller/apiserver.c

@@ -48,7 +48,7 @@ static int xce_apiserver_push_workers(cluster_t* c, endpoint_t* ep)
     for (i = 0; i < workers.n_total; i++) {
         xce_worker_t* w = workers.workers[i];
 
-        free_name_val_list(&(w->resvals_to_sched), w->nresvals_to_sched);
+        free_name_val_list(&(w->resvals_to_sched), &(w->nresvals_to_sched));
     }
 
     unlock_collect_workers(&wlist);

src/controller/dataex.c

@@ -417,7 +417,7 @@ void unlock_collect_workers(xlist_t* l)
             continue;
         }
 
-        free_name_val_list(&(w->resvals_to_sched), w->nresvals_to_sched);
+        free_name_val_list(&(w->resvals_to_sched), &(w->nresvals_to_sched));
 
         w1 = CONTAINER_OF(w, worker_t, host);
         unlock(w1);

src/controller/opget.c

@@ -125,7 +125,7 @@ static int do_reply_workerlist(cluster_t* c, endpoint_t* ep,
     for (i = 0; i < workerdata.n_total; i++) {
         xce_worker_t* w = workerdata.workers[i];
 
-        free_name_val_list(&(w->resvals_to_sched), w->nresvals_to_sched);
+        free_name_val_list(&(w->resvals_to_sched), &(w->nresvals_to_sched));
     }
 
     unlock_collect_workers(&wlist);

src/controller/reply.c

@@ -63,7 +63,7 @@ int handle_clusterconf(cluster_t* c, endpoint_t* ep, xce_request_t* request)
     for (i = 0; i < clusterconf.wlist.count; i++) {
         xce_worker_t* w = clusterconf.wlist.workers[i];
 
-        free_name_val_list(&(w->resvals_to_sched), w->nresvals_to_sched);
+        free_name_val_list(&(w->resvals_to_sched), &(w->nresvals_to_sched));
     }
 
     unlock_collect_queues(&qlist);

src/controller/sched.c

@@ -143,7 +143,7 @@ static int xcesched_push_configs(cluster_t* c)
     rc = xce_pushconfig_req(c->sched.ep, c->myhost, &configdata);
 
     free_name_val_list(&(configdata.data.conf4sched->resvals),
-                       configdata.data.conf4sched->nresvals);
+                       &(configdata.data.conf4sched->nresvals));
 
     FREEUP(configdata.data.conf4sched);
 
@@ -223,7 +223,7 @@ static int xcesched_push_workers(cluster_t* c)
     for (i = 0; i < workers.n_total; i++) {
         xce_worker_t* w = workers.workers[i];
 
-        free_name_val_list(&(w->resvals_to_sched), w->nresvals_to_sched);
+        free_name_val_list(&(w->resvals_to_sched), &(w->nresvals_to_sched));
     }
 
     unlock_collect_workers(&wlist);
@@ -461,7 +461,7 @@ static int sched_worker_change(int type, int situation, void* data,
 #if 0
     /*FIXME*/
     free_name_val_list(&(w->host.resvals_to_sched),
-                       w->host.nresvals_to_sched);
+                       &(w->host.nresvals_to_sched));
 #endif
     xlist_fini(&resvalist);
 

src/include/utils.h

@@ -127,7 +127,7 @@ extern xce_timewindow_config_t* dup_timewindow_config(xce_timewindow_config_t*);
 extern void free_resource_thresholds(xce_res_threshold_t**, int);
 extern xce_res_threshold_t** dup_resource_thresholds(xce_res_threshold_t**,
                                                      int);
-extern void     free_name_val_list(xce_name_val_t***, int);
+extern void     free_name_val_list(xce_name_val_t***, int*);
 extern void     free_strlist(xce_strlist_t*);
 extern int      fmt_jobid_ex(char*, size_t, uint64_t, char*, char*);
 extern int      fmt_jobid(char*, size_t, uint64_t);

src/lib/utils.c

@@ -385,16 +385,14 @@ int copy_strlist(xce_strlist_t* dst, xce_strlist_t src)
     }
     return 0;
 }
-void free_name_val_list(xce_name_val_t*** vals, int count)
+void free_name_val_list(xce_name_val_t*** vals, int *count_p)
 {
     xce_name_val_t** resvals = *vals;
+    int              count   = *count_p;
     int              i;
 
-    if (resvals == NULL) {
-        return;
-    }
-
-    if (count <= 0) {
+    if (resvals == NULL || count <= 0) {
+        *count_p = 0;
         return;
     }
 
@@ -418,7 +416,8 @@ void free_name_val_list(xce_name_val_t*** vals, int count)
     }
 
     FREEUP(resvals);
-    *vals = NULL;
+    *vals    = NULL;
+    *count_p = 0;
 }
 
 void free_strlist(xce_strlist_t* l)