tree-wide: take benefit of the fact that hashmap_free() returns NULL

And set_free() too.

Another Coccinelle patch.

coccinelle/hashmap_free.cocci

@@ -0,0 +1,54 @@
+@@
+expression p;
+@@
+- set_free(p);
+- p = NULL;
++ p = set_free(p);
+@@
+expression p;
+@@
+- if (p)
+-         set_free(p);
+- p = NULL;
++ p = set_free(p);
+@@
+expression p;
+@@
+- if (p) {
+-         set_free(p);
+-         p = NULL;
+- }
++ p = set_free(p);
+@@
+expression p;
+@@
+- if (p)
+-         set_free(p);
++ set_free(p);
+@@
+expression p;
+@@
+- hashmap_free(p);
+- p = NULL;
++ p = hashmap_free(p);
+@@
+expression p;
+@@
+- if (p)
+-         hashmap_free(p);
+- p = NULL;
++ p = hashmap_free(p);
+@@
+expression p;
+@@
+- if (p) {
+-         hashmap_free(p);
+-         p = NULL;
+- }
++ p = hashmap_free(p);
+@@
+expression p;
+@@
+- if (p)
+-         hashmap_free(p);
++ hashmap_free(p);

src/core/automount.c

@@ -129,10 +129,8 @@ static void automount_done(Unit *u) {
 
         a->where = mfree(a->where);
 
-        set_free(a->tokens);
-        a->tokens = NULL;
-        set_free(a->expire_tokens);
-        a->expire_tokens = NULL;
+        a->tokens = set_free(a->tokens);
+        a->expire_tokens = set_free(a->expire_tokens);
 
         a->expire_event_source = sd_event_source_unref(a->expire_event_source);
 }

src/core/dbus.c

@@ -1055,8 +1055,7 @@ void bus_done(Manager *m) {
         while ((b = set_steal_first(m->private_buses)))
                 destroy_bus(m, &b);
 
-        set_free(m->private_buses);
-        m->private_buses = NULL;
+        m->private_buses = set_free(m->private_buses);
 
         m->subscribed = sd_bus_track_unref(m->subscribed);
         m->deserialized_subscribed = strv_free(m->deserialized_subscribed);

src/core/device.c

@@ -594,8 +594,7 @@ static void device_shutdown(Manager *m) {
                 m->udev_monitor = NULL;
         }
 
-        hashmap_free(m->devices_by_sysfs);
-        m->devices_by_sysfs = NULL;
+        m->devices_by_sysfs = hashmap_free(m->devices_by_sysfs);
 }
 
 static int device_enumerate(Manager *m) {

src/core/execute.c

@@ -2025,14 +2025,9 @@ void exec_context_done(ExecContext *c) {
         c->selinux_context = mfree(c->selinux_context);
         c->apparmor_profile = mfree(c->apparmor_profile);
 
-        set_free(c->syscall_filter);
-        c->syscall_filter = NULL;
-
-        set_free(c->syscall_archs);
-        c->syscall_archs = NULL;
-
-        set_free(c->address_families);
-        c->address_families = NULL;
+        c->syscall_filter = set_free(c->syscall_filter);
+        c->syscall_archs = set_free(c->syscall_archs);
+        c->address_families = set_free(c->address_families);
 
         c->runtime_directory = strv_free(c->runtime_directory);
 

src/core/load-fragment.c

@@ -2302,8 +2302,7 @@ int config_parse_syscall_filter(
 
         if (isempty(rvalue)) {
                 /* Empty assignment resets the list */
-                set_free(c->syscall_filter);
-                c->syscall_filter = NULL;
+                c->syscall_filter = set_free(c->syscall_filter);
                 c->syscall_whitelist = false;
                 return 0;
         }
@@ -2401,8 +2400,7 @@ int config_parse_syscall_archs(
         int r;
 
         if (isempty(rvalue)) {
-                set_free(*archs);
-                *archs = NULL;
+                *archs = set_free(*archs);
                 return 0;
         }
 
@@ -2498,8 +2496,7 @@ int config_parse_address_families(
 
         if (isempty(rvalue)) {
                 /* Empty assignment resets the list */
-                set_free(c->address_families);
-                c->address_families = NULL;
+                c->address_families = set_free(c->address_families);
                 c->address_families_whitelist = false;
                 return 0;
         }

src/core/main.c

@@ -1846,8 +1846,7 @@ finish:
 
         arg_default_environment = strv_free(arg_default_environment);
 
-        set_free(arg_syscall_archs);
-        arg_syscall_archs = NULL;
+        arg_syscall_archs = set_free(arg_syscall_archs);
 
         mac_selinux_finish();
 

src/core/swap.c

@@ -1254,8 +1254,7 @@ static void swap_shutdown(Manager *m) {
 
         m->proc_swaps = safe_fclose(m->proc_swaps);
 
-        hashmap_free(m->swaps_by_devnode);
-        m->swaps_by_devnode = NULL;
+        m->swaps_by_devnode = hashmap_free(m->swaps_by_devnode);
 }
 
 static int swap_enumerate(Manager *m) {

src/core/unit.c

@@ -673,8 +673,7 @@ static void merge_dependencies(Unit *u, Unit *other, const char *other_id, UnitD
         /* The move cannot fail. The caller must have performed a reservation. */
         assert_se(complete_move(&u->dependencies[d], &other->dependencies[d]) == 0);
 
-        set_free(other->dependencies[d]);
-        other->dependencies[d] = NULL;
+        other->dependencies[d] = set_free(other->dependencies[d]);
 }
 
 int unit_merge(Unit *u, Unit *other) {

src/resolve/resolved-dns-zone.c

@@ -90,11 +90,8 @@ void dns_zone_flush(DnsZone *z) {
         assert(hashmap_size(z->by_key) == 0);
         assert(hashmap_size(z->by_name) == 0);
 
-        hashmap_free(z->by_key);
-        z->by_key = NULL;
-
-        hashmap_free(z->by_name);
-        z->by_name = NULL;
+        z->by_key = hashmap_free(z->by_key);
+        z->by_name = hashmap_free(z->by_name);
 }
 
 static DnsZoneItem* dns_zone_get(DnsZone *z, DnsResourceRecord *rr) {