From d27610cfef24a985116ed88f29a462f627745b19 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Tue, 19 May 2015 16:00:24 +0200
Subject: [PATCH] core: enforce a ratelimiter when stopping units due to
 StopWhenUnneeded=1

Otherwise we might end up in an endless stop loop.

http://lists.freedesktop.org/archives/systemd-devel/2015-April/030224.html
(cherry picked from commit bea355dac94e82697aa98e25d80ee4248263bf92)

Related: #1775291
---
 src/core/unit.c | 10 ++++++++++
 src/core/unit.h |  3 +++
 2 files changed, 13 insertions(+)

diff --git a/src/core/unit.c b/src/core/unit.c
index 502830d2cb..750b8b9a5c 100644
--- a/src/core/unit.c
+++ b/src/core/unit.c
@@ -97,6 +97,8 @@ Unit *unit_new(Manager *m, size_t size) {
         u->on_failure_job_mode = JOB_REPLACE;
         u->sigchldgen = 0;
 
+        RATELIMIT_INIT(u->check_unneeded_ratelimit, 10 * USEC_PER_SEC, 16);
+
         return u;
 }
 
@@ -1612,6 +1614,14 @@ static void unit_check_unneeded(Unit *u) {
                 if (unit_active_or_pending(other))
                         return;
 
+        /* If stopping a unit fails continously we might enter a stop
+         * loop here, hence stop acting on the service being
+         * unnecessary after a while. */
+        if (!ratelimit_test(&u->check_unneeded_ratelimit)) {
+                log_unit_warning(u->id, "Unit not needed anymore, but not stopping since we tried this too often recently.");
+                return;
+        }
+
         log_unit_info(u->id, "Unit %s is not needed anymore. Stopping.", u->id);
 
         /* Ok, nobody needs us anymore. Sniff. Then let's commit suicide */
diff --git a/src/core/unit.h b/src/core/unit.h
index 8cc7a9e0b2..e930d8ba5f 100644
--- a/src/core/unit.h
+++ b/src/core/unit.h
@@ -192,6 +192,9 @@ struct Unit {
         /* Error code when we didn't manage to load the unit (negative) */
         int load_error;
 
+        /* Make sure we never enter endless loops with the check unneeded logic */
+        RateLimit check_unneeded_ratelimit;
+
         /* Cached unit file state and preset */
         UnitFileState unit_file_state;
         int unit_file_preset;