systemd: skip automatic restart when a JOB_STOP job is pending

Signed-off-by: Kyle Sessions <[email protected]>

Dockerfile

@@ -76,6 +76,7 @@ RUN last_patch=$(awk '/^Patch[0-9]+/ { line = NR } END { print line }' systemd.s
         echo 'Patch9501: 9501-cgroup-util-accept-cgroup-hierarchy-base-as-option.patch'; \
         echo 'Patch9502: 9502-core-move-initialization-of-.slice-and-init.scope-in.patch'; \
         echo 'Patch9503: 9503-core-drop-.slice-from-shipped-units.patch'; \
+        echo 'Patch9504: 9504-core-skip-restart-when-a-JOB_STOP-job-is-pending.patch'; \
         echo ; \
     } >>systemd.mod.spec; \
     tail -n+$((last_patch + 1)) systemd.spec >>systemd.mod.spec; \

systemd-patches/9504-core-skip-restart-when-a-JOB_STOP-job-is-pending.patch

@@ -0,0 +1,52 @@
+From c972880640ee19e89ce9265d8eae1b3aae190332 Mon Sep 17 00:00:00 2001
+From: Franck Bui <[email protected]>
+Date: Fri, 18 Feb 2022 10:06:24 +0100
+Subject: [PATCH] core: really skip automatic restart when a JOB_STOP job is
+ pending
+
+It's not clear why we rescheduled a service auto restart while a stop job for
+the unit was pending. The comment claims that the unit shouldn't be restarted
+but the code did reschedule an auto restart meanwhile.
+
+In practice that was rarely an issue because the service waited for the next
+auto restart to be rescheduled, letting the queued stop job to be proceed and
+service_stop() to be called preventing the next restart to complete.
+
+However when RestartSec=0, the timer expired right away making PID1 to
+reschedule the unit again, making the timer expired right away... and so
+on. This busy loop prevented PID1 to handle any queued jobs (and hence giving
+no chance to the start rate limiting to trigger), which made the busy loop last
+forever.
+
+This patch breaks this loop by skipping the reschedule of the unit auto restart
+and hence not depending on the value of u->restart_usec anymore.
+
+Fixes: #13667
+
+[kssessio: backport to v219]
+Signed-off-by: Kyle Sessions <[email protected]>
+---
+ src/core/service.c | 7 +------
+ 1 file changed, 1 insertion(+), 6 deletions(-)
+
+diff --git a/src/core/service.c b/src/core/service.c
+index 15e29be..fa2af05 100644
+--- a/src/core/service.c
++++ b/src/core/service.c
+@@ -1622,12 +1622,7 @@ static void service_enter_restart(Service *s) {
+
+         if (UNIT(s)->job && UNIT(s)->job->type == JOB_STOP) {
+                 /* Don't restart things if we are going down anyway */
+-                log_unit_info(UNIT(s)->id, "Stop job pending for unit, delaying automatic restart.");
+-
+-                r = service_arm_timer(s, s->restart_usec);
+-                if (r < 0)
+-                        goto fail;
+-
++                log_unit_info(UNIT(s)->id, "Stop job pending for unit, skipping automatic restart.");
+                 return;
+         }
+
+-- 
+2.40.1
+