From afb5e76925f7f4992252cc392dac4dda6c4faf69 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Fri, 11 Sep 2020 19:57:09 +0200
Subject: [PATCH] core: propagate unit start limit hit state to triggering path
 unit

We already do this for socket and automount units, do it for path units
too: if the triggered service keeps hitting the start limit, then fail
the triggering unit too, so that we don#t busy loop forever.

(Note that this leaves only timer units out in the cold for this kind of
protection, but it shouldn't matter there, as they are naturally
protected against busy loops: they are scheduled by time anyway).

Fixes: #16669
(cherry picked from commit 47ab8f73e3468b6e5a48218eacdb830e978d2cfd)

Related: #2065322
---
 src/core/path.c | 15 +++++++++++++++
 src/core/path.h |  1 +
 2 files changed, 16 insertions(+)

diff --git a/src/core/path.c b/src/core/path.c
index a7c2e0b7c1..c2facf0b16 100644
--- a/src/core/path.c
+++ b/src/core/path.c
@@ -701,6 +701,20 @@ static void path_trigger_notify(Unit *u, Unit *other) {
         /* Filter out invocations with bogus state */
         assert(UNIT_IS_LOAD_COMPLETE(other->load_state));
 
+        /* Don't propagate state changes from the triggered unit if we are already down */
+        if (!IN_SET(p->state, PATH_WAITING, PATH_RUNNING))
+                return;
+
+        /* Propagate start limit hit state */
+        if (other->start_limit_hit) {
+                path_enter_dead(p, PATH_FAILURE_UNIT_START_LIMIT_HIT);
+                return;
+        }
+
+        /* Don't propagate anything if there's still a job queued */
+        if (other->job)
+                return;
+
         if (p->state == PATH_RUNNING &&
             UNIT_IS_INACTIVE_OR_FAILED(unit_active_state(other))) {
                 log_unit_debug(UNIT(p), "Got notified about unit deactivation.");
@@ -752,6 +766,7 @@ static const char* const path_result_table[_PATH_RESULT_MAX] = {
         [PATH_SUCCESS] = "success",
         [PATH_FAILURE_RESOURCES] = "resources",
         [PATH_FAILURE_START_LIMIT_HIT] = "start-limit-hit",
+        [PATH_FAILURE_UNIT_START_LIMIT_HIT] = "unit-start-limit-hit",
 };
 
 DEFINE_STRING_TABLE_LOOKUP(path_result, PathResult);
diff --git a/src/core/path.h b/src/core/path.h
index 4d4b6236c2..8a69f06c13 100644
--- a/src/core/path.h
+++ b/src/core/path.h
@@ -45,6 +45,7 @@ typedef enum PathResult {
         PATH_SUCCESS,
         PATH_FAILURE_RESOURCES,
         PATH_FAILURE_START_LIMIT_HIT,
+        PATH_FAILURE_UNIT_START_LIMIT_HIT,
         _PATH_RESULT_MAX,
         _PATH_RESULT_INVALID = -1
 } PathResult;