From a246b1c63f082565c4492d8bdd945623863df07d Mon Sep 17 00:00:00 2001
From: Ryan Wilson <ryantimwilson@meta.com>
Date: Tue, 29 Oct 2024 10:25:53 -0700
Subject: [PATCH] core: Add debug logging for systemd killing services/units

---
 src/basic/pidref.c |  2 ++
 src/core/service.c |  3 +++
 src/core/unit.c    | 12 ++++++++++++
 src/core/unit.h    |  3 +++
 4 files changed, 20 insertions(+)

diff --git a/src/basic/pidref.c b/src/basic/pidref.c
index 69a010210d..6bd7198d0d 100644
--- a/src/basic/pidref.c
+++ b/src/basic/pidref.c
@@ -268,6 +268,8 @@ int pidref_kill(const PidRef *pidref, int sig) {
         if (!pidref)
                 return -ESRCH;
 
+        log_debug("Sending signal %s for PID " PID_FMT " and PIDFD %d", signal_to_string(sig), pidref->pid, pidref->fd);
+
         if (pidref->fd >= 0)
                 return RET_NERRNO(pidfd_send_signal(pidref->fd, sig, NULL, 0));
 
diff --git a/src/core/service.c b/src/core/service.c
index 6e81460ad0..577f1f067d 100644
--- a/src/core/service.c
+++ b/src/core/service.c
@@ -2138,6 +2138,9 @@ static void service_enter_signal(Service *s, ServiceState state, ServiceResult f
          * died now */
         (void) unit_enqueue_rewatch_pids(UNIT(s));
 
+        log_unit_debug(UNIT(s), "Sending signal to unit for state %s with result %s",
+                       service_state_to_string(state), service_result_to_string(f));
+
         kill_operation = state_to_kill_operation(s, state);
         r = unit_kill_context(UNIT(s), kill_operation);
         if (r < 0) {
diff --git a/src/core/unit.c b/src/core/unit.c
index 136b7aacb0..3a47331985 100644
--- a/src/core/unit.c
+++ b/src/core/unit.c
@@ -4796,6 +4796,16 @@ static int unit_kill_context_one(
         return !is_alien;
 }
 
+static const char* const kill_operation_table[_KILL_OPERATION_MAX] = {
+        [KILL_TERMINATE]         = "terminate",
+        [KILL_TERMINATE_AND_LOG] = "terminate-and-log",
+        [KILL_RESTART]           = "restart",
+        [KILL_KILL]              = "kill",
+        [KILL_WATCHDOG]          = "watchdog",
+};
+
+DEFINE_STRING_TABLE_LOOKUP(kill_operation, KillOperation);
+
 int unit_kill_context(Unit *u, KillOperation k) {
         bool wait_for_exit = false, send_sighup;
         cg_kill_log_func_t log_func = NULL;
@@ -4807,6 +4817,8 @@ int unit_kill_context(Unit *u, KillOperation k) {
          * if we killed something worth waiting for, 0 otherwise. Do not confuse with unit_kill_common()
          * which is used for user-requested killing of unit processes. */
 
+        log_unit_debug(u, "Killing unit context with operation %s", kill_operation_to_string(k));
+
         KillContext *c = unit_get_kill_context(u);
         if (!c || c->kill_mode == KILL_NONE)
                 return 0;
diff --git a/src/core/unit.h b/src/core/unit.h
index b135fecc51..e46dfb7c58 100644
--- a/src/core/unit.h
+++ b/src/core/unit.h
@@ -1053,6 +1053,9 @@ UnitMountDependencyType unit_mount_dependency_type_from_string(const char *s) _c
 const char* unit_mount_dependency_type_to_string(UnitMountDependencyType t) _const_;
 UnitDependency unit_mount_dependency_type_to_dependency_type(UnitMountDependencyType t) _pure_;
 
+const char* kill_operation_to_string(KillOperation t) _const_;
+KillOperation kill_operation_from_string(const char *s) _pure_;
+
 /* Macros which append UNIT= or USER_UNIT= to the message */
 
 #define log_unit_full_errno_zerook(unit, level, error, ...)             \
-- 
2.43.5