core/cgroup: make sure deserialized accounting data is not voided

Currently, cgroup_path is (de-)serialized after all the cached
accounting data. This is bogus though, since unit_set_cgroup_path()
destroys the CGroupRuntime object and starts afresh, discarding
all deserialized values. This matters especially for IP accounting,
whose BPF maps get recreated on reload/reexec and the previous values
are exclusively retrievable from deserialization. Let's hence swap things
around and serialize cgroup_path first, accounting data only afterwards.

diff --git a/src/core/cgroup.c b/src/core/cgroup.c
index 4e15de8e6bcee580de276cb07d1c2d3719cfc970..6d37c031274d759dd053467930b670baef160177 100644 (file)
--- a/src/core/cgroup.c
+++ b/src/core/cgroup.c
@@ -4283,6 +4283,15 @@ int cgroup_runtime_serialize(Unit *u, FILE *f, FDSet *fds) {
         if (!crt)
                 return 0;
 
+        if (crt->cgroup_path)
+                (void) serialize_item(f, "cgroup", crt->cgroup_path);
+        if (crt->cgroup_id != 0)
+                (void) serialize_item_format(f, "cgroup-id", "%" PRIu64, crt->cgroup_id);
+
+        (void) serialize_cgroup_mask(f, "cgroup-realized-mask", crt->cgroup_realized_mask);
+        (void) serialize_cgroup_mask(f, "cgroup-enabled-mask", crt->cgroup_enabled_mask);
+        (void) serialize_cgroup_mask(f, "cgroup-invalidated-mask", crt->cgroup_invalidated_mask);
+
         (void) serialize_item_format(f, "cpu-usage-base", "%" PRIu64, crt->cpu_usage_base);
         if (crt->cpu_usage_last != NSEC_INFINITY)
                 (void) serialize_item_format(f, "cpu-usage-last", "%" PRIu64, crt->cpu_usage_last);
@@ -4316,15 +4325,6 @@ int cgroup_runtime_serialize(Unit *u, FILE *f, FDSet *fds) {
                         (void) serialize_item_format(f, io_accounting_metric_field_last_to_string(im), "%" PRIu64, crt->io_accounting_last[im]);
         }
 
-        if (crt->cgroup_path)
-                (void) serialize_item(f, "cgroup", crt->cgroup_path);
-        if (crt->cgroup_id != 0)
-                (void) serialize_item_format(f, "cgroup-id", "%" PRIu64, crt->cgroup_id);
-
-        (void) serialize_cgroup_mask(f, "cgroup-realized-mask", crt->cgroup_realized_mask);
-        (void) serialize_cgroup_mask(f, "cgroup-enabled-mask", crt->cgroup_enabled_mask);
-        (void) serialize_cgroup_mask(f, "cgroup-invalidated-mask", crt->cgroup_invalidated_mask);
-
         (void) bpf_socket_bind_serialize(u, f, fds);
 
         (void) bpf_program_serialize_attachment(f, fds, "ip-bpf-ingress-installed", crt->ip_bpf_ingress_installed);