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run: fix generated unit name clash after soft-reboot

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When sd-run connects to D-Bus rather than the private socket, it will
generate the transient unit name using the bus ID assigned by the D-Bus
broker/daemon. The issue is that this ID is only unique per D-Bus run,
if the broker/daemon restarts it starts again from 1, and it's a simple
incremental counter for each client.
So if a transient unit run-u6.service starts and fails, and it is not
collected (default on failure), and the system soft-reboots, any new
transient unit might conflict as the counter will restart:

Failed to start transient service unit: Unit run-u6.service was already loaded or has a fragment file.

Get the soft-reboot counter, and if it's greater than zero, append it
to the autogenerated unit name to avoid clashes.
This commit is contained in:
Luca Boccassi
2024-03-27 21:14:15 +00:00
committed by Yu Watanabe
parent 2a4fb037cb
commit ed35851693
2 changed files with 31 additions and 3 deletions
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21
src/run/run.c
View File

@@ -1313,6 +1313,7 @@ static int transient_timer_set_properties(sd_bus_message *m) {
}
static int make_unit_name(sd_bus *bus, UnitType t, char **ret) {
unsigned soft_reboots_count = 0;
const char *unique, *id;
char *p;
int r;
@@ -1351,9 +1352,23 @@ static int make_unit_name(sd_bus *bus, UnitType t, char **ret) {
"Unique name %s has unexpected format.",
unique);
p = strjoin("run-u", id, ".", unit_type_to_string(t));
if (!p)
return log_oom();
/* The unique D-Bus names are actually unique per D-Bus instance, so on soft-reboot they will wrap
* and start over since the D-Bus broker is restarted. If there's a failed unit left behind that
* hasn't been garbage collected, we'll conflict. Append the soft-reboot counter to avoid clashing. */
_cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
r = bus_get_property_trivial(
bus, bus_systemd_mgr, "SoftRebootsCount", &error, 'u', &soft_reboots_count);
if (r < 0)
log_debug_errno(r, "Failed to get SoftRebootsCount property, ignoring: %s", bus_error_message(&error, r));
if (soft_reboots_count > 0) {
if (asprintf(&p, "run-u%s-s%u.%s", id, soft_reboots_count, unit_type_to_string(t)) < 0)
return log_oom();
} else {
p = strjoin("run-u", id, ".", unit_type_to_string(t));
if (!p)
return log_oom();
}
*ret = p;
return 0;

13
test/units/testsuite-82.sh
View File

@@ -146,6 +146,11 @@ elif [ -f /run/testsuite82.touch ]; then
# Restart the unit that is not supposed to survive
systemd-run --collect --service-type=exec --unit=testsuite-82-nosurvive.service sleep infinity
# Now ensure there are no naming clashes and a bunch of transient units all succeed
for _ in $(seq 1 25); do
systemd-run --wait true
done
# 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/testsuite82.touch2
@@ -227,6 +232,14 @@ EOF
systemd-inhibit --what=shutdown --who=test --why=test --mode=delay \
sleep infinity
# Enqueue a bunch of failing units to try and trigger the transient name clash that happens due to D-Bus
# being restarted and the "unique" bus IDs not being unique across restarts
for _ in $(seq 1 25); do
# Use --wait to ensure we connect to the system bus instead of the private bus (otherwise a UUID is
# used instead of the bus ID)
systemd-run --wait false || true
done
# Now issue the soft reboot. We should be right back soon.
touch /run/testsuite82.touch
systemctl --no-block --check-inhibitors=yes soft-reboot