From b50f6dbe574b0421db7dbf200ad951186382277d Mon Sep 17 00:00:00 2001
From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Wed, 9 Apr 2025 22:10:42 +0900
Subject: [PATCH 1/3] core/socket: do not enter failed state when we cannot
 start service due to conflicting transaction being queued

Otherwise, e.g. on soft-reboot, socket unit may enter the failed state
and the socket buffer will be cleared.
---
 src/core/socket.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/core/socket.c b/src/core/socket.c
index 861aaba3d4..7bff0a2d03 100644
--- a/src/core/socket.c
+++ b/src/core/socket.c
@@ -2356,6 +2356,8 @@ static void socket_enter_running(Socket *s, int cfd_in) {
                         }
 
                         r = manager_add_job(UNIT(s)->manager, JOB_START, UNIT_DEREF(s->service), JOB_REPLACE, &error, /* ret = */ NULL);
+                        if (r == -EDEADLK)
+                                return (void) log_unit_debug_errno(UNIT(s), r, "Failed to queue service startup job, ignoring: %s", bus_error_message(&error, r));
                         if (r < 0)
                                 goto queue_error;
                 }

From 0d1819e791a97367c2c0cead738111cfcc1e7491 Mon Sep 17 00:00:00 2001
From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Mon, 7 Apr 2025 17:31:05 +0900
Subject: [PATCH 2/3] units: stop systemd-udevd before soft-reboot

Otherwise, queued uevents may be lost on soft-reboot.

Similar to f89985ca494b79b2beed47e1f10d46ef2d59ce3e, but for
systemd-udevd.
---
 units/systemd-udevd.service.in | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/units/systemd-udevd.service.in b/units/systemd-udevd.service.in
index 8e343ef836..ef604e9215 100644
--- a/units/systemd-udevd.service.in
+++ b/units/systemd-udevd.service.in
@@ -16,6 +16,14 @@ Before=sysinit.target
 Wants=systemd-udev-load-credentials.service
 ConditionPathIsReadWrite=/sys
 
+# To avoid systemd-udevd being SIGKILLed during a soft reboot,
+# and causing queued uevents to be lost.
+# Note, typically soft-reboot.target will be never reached,
+# and systemd-soft-reboot.service will trigger soft-reboot.
+# Hence, this must be stopped before systemd-soft-reboot.service.
+Before=soft-reboot.target systemd-soft-reboot.service
+Conflicts=soft-reboot.target
+
 [Service]
 CapabilityBoundingSet=~CAP_SYS_TIME CAP_WAKE_ALARM
 Delegate=pids

From 28659e1eacbe09b75ace4b4cb07a1d5dd1eb8c66 Mon Sep 17 00:00:00 2001
From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Wed, 9 Apr 2025 22:14:56 +0900
Subject: [PATCH 3/3] TEST-82-SOFTREBOOT: add test case for uevents generated
 during soft-reboot

---
 test/units/TEST-82-SOFTREBOOT.sh | 60 ++++++++++++++++++++++++++++++++
 1 file changed, 60 insertions(+)

diff --git a/test/units/TEST-82-SOFTREBOOT.sh b/test/units/TEST-82-SOFTREBOOT.sh
index 9f76c86245..e0bf27342b 100755
--- a/test/units/TEST-82-SOFTREBOOT.sh
+++ b/test/units/TEST-82-SOFTREBOOT.sh
@@ -34,6 +34,56 @@ if [[ -L /run/nextroot ]]; then
     rm -f /run/nextroot
 fi
 
+trigger_uevent() {
+    local rule=/run/udev/rules.d/99-softreboot.rules
+
+    if [[ ! -f "$rule" ]]; then
+        mkdir -p /run/udev/rules.d
+        cat >"$rule" <<EOF
+SUBSYSTEM!="mem", GOTO="end"
+KERNEL!="null", GOTO="end"
+ACTION=="remove", GOTO="end"
+
+IMPORT{db}="HISTORY"
+IMPORT{program}="/bin/bash -c 'systemctl show --property=SoftRebootsCount'"
+ENV{HISTORY}+="%E{ACTION}_%E{SEQNUM}_%E{SoftRebootsCount}"
+
+LABEL="end"
+EOF
+        udevadm control --reload
+    fi
+
+    systemd-run \
+        --unit=TEST-82-SOFTREBOOT-trigger.service \
+        --property DefaultDependencies=no \
+        --property Conflicts=soft-reboot.target \
+        --property Before=soft-reboot.target \
+        --property Before=systemd-soft-reboot.service \
+        --property Before=systemd-udevd.service \
+        --property RemainAfterExit=yes \
+        --property 'ExecStop=udevadm trigger --action bind /dev/null' \
+        true
+}
+
+check_device_property() {
+    local expected_count=${1:?}
+
+    udevadm info --no-pager /dev/null
+
+    local action seqnum softreboot_count
+    local previous_seqnum=0
+    local count=0
+    while read -r action seqnum softreboot_count; do
+        test "$seqnum" -gt "$previous_seqnum"
+        assert_eq "$action" "bind"
+        assert_eq "$softreboot_count" "$((++count))"
+
+        previous_seqnum="$seqnum"
+    done < <(udevadm info -q property --property=HISTORY --value /dev/null | sed -e 's/ /\n/g; s/_/ /g')
+
+    assert_eq "$count" "$expected_count"
+}
+
 systemd-analyze log-level debug
 
 export SYSTEMD_LOG_LEVEL=debug
@@ -70,6 +120,8 @@ if [ -f /run/TEST-82-SOFTREBOOT.touch3 ]; then
     journalctl -o short-monotonic --no-hostname --grep '(will soft-reboot|KILL|corrupt)'
     assert_eq "$(journalctl -q -o short-monotonic -u systemd-journald.service --grep 'corrupt')" ""
 
+    check_device_property 3
+
     # All succeeded, exit cleanly now
 
 elif [ -f /run/TEST-82-SOFTREBOOT.touch2 ]; then
@@ -110,6 +162,9 @@ elif [ -f /run/TEST-82-SOFTREBOOT.touch2 ]; then
     # Restart the unit that is not supposed to survive
     systemd-run --collect --service-type=exec --unit=TEST-82-SOFTREBOOT-nosurvive.service sleep infinity
 
+    check_device_property 2
+    trigger_uevent
+
     # Now issue the soft reboot. We should be right back soon.
     touch /run/TEST-82-SOFTREBOOT.touch3
     systemctl --no-block soft-reboot
@@ -176,6 +231,9 @@ elif [ -f /run/TEST-82-SOFTREBOOT.touch ]; then
         systemd-run --wait true
     done
 
+    check_device_property 1
+    trigger_uevent
+
     # Now issue the soft reboot. We should be right back soon. Given /run/nextroot exists, we should
     # automatically do a softreboot instead of normal reboot.
     touch /run/TEST-82-SOFTREBOOT.touch2
@@ -266,6 +324,8 @@ EOF
         systemd-run --wait false || true
     done
 
+    trigger_uevent
+
     # Now issue the soft reboot. We should be right back soon.
     touch /run/TEST-82-SOFTREBOOT.touch
     systemctl --no-block --check-inhibitors=yes soft-reboot