(RHEL-115032) Increment start limit counter only when we can start the unit

src/core/automount.c

@@ -1040,7 +1040,7 @@ static bool automount_supported(void) {
         return supported;
 }
 
-static int automount_can_start(Unit *u) {
+static int automount_test_startable(Unit *u) {
         Automount *a = ASSERT_PTR(AUTOMOUNT(u));
         int r;
 
@@ -1050,7 +1050,7 @@ static int automount_can_start(Unit *u) {
                 return r;
         }
 
-        return 1;
+        return true;
 }
 
 static const char* const automount_result_table[_AUTOMOUNT_RESULT_MAX] = {
@@ -1116,5 +1116,5 @@ const UnitVTable automount_vtable = {
                 },
         },
 
-        .can_start = automount_can_start,
+        .test_startable = automount_test_startable,
 };

src/core/mount.c

@@ -1288,19 +1288,6 @@ static int mount_start(Unit *u) {
         Mount *m = ASSERT_PTR(MOUNT(u));
         int r;
 
-        /* We cannot fulfill this request right now, try again later
-         * please! */
-        if (IN_SET(m->state,
-                   MOUNT_UNMOUNTING,
-                   MOUNT_UNMOUNTING_SIGTERM,
-                   MOUNT_UNMOUNTING_SIGKILL,
-                   MOUNT_CLEANING))
-                return -EAGAIN;
-
-        /* Already on it! */
-        if (IN_SET(m->state, MOUNT_MOUNTING, MOUNT_MOUNTING_DONE))
-                return 0;
-
         assert(IN_SET(m->state, MOUNT_DEAD, MOUNT_FAILED));
 
         r = unit_acquire_invocation_id(u);
@@ -2292,17 +2279,21 @@ static int mount_can_clean(Unit *u, ExecCleanMask *ret) {
         return exec_context_get_clean_mask(&m->exec_context, ret);
 }
 
-static int mount_can_start(Unit *u) {
+static int mount_test_startable(Unit *u) {
         Mount *m = ASSERT_PTR(MOUNT(u));
         int r;
 
+        /* It is already being started. */
+        if (IN_SET(m->state, MOUNT_MOUNTING, MOUNT_MOUNTING_DONE))
+                return false;
+
         r = unit_test_start_limit(u);
         if (r < 0) {
                 mount_enter_dead(m, MOUNT_FAILURE_START_LIMIT_HIT, /* flush_result = */ false);
                 return r;
         }
 
-        return 1;
+        return true;
 }
 
 static int mount_subsystem_ratelimited(Manager *m) {
@@ -2467,7 +2458,7 @@ const UnitVTable mount_vtable = {
                 },
         },
 
-        .can_start = mount_can_start,
+        .test_startable = mount_test_startable,
 
         .notify_plymouth = true,
 };

src/core/path.c

@@ -898,7 +898,7 @@ static void path_reset_failed(Unit *u) {
         p->result = PATH_SUCCESS;
 }
 
-static int path_can_start(Unit *u) {
+static int path_test_startable(Unit *u) {
         Path *p = ASSERT_PTR(PATH(u));
         int r;
 
@@ -908,7 +908,7 @@ static int path_can_start(Unit *u) {
                 return r;
         }
 
-        return 1;
+        return true;
 }
 
 static void activation_details_path_done(ActivationDetails *details) {
@@ -1042,7 +1042,7 @@ const UnitVTable path_vtable = {
 
         .bus_set_property = bus_path_set_property,
 
-        .can_start = path_can_start,
+        .test_startable = path_test_startable,
 };
 
 const ActivationDetailsVTable activation_details_path_vtable = {

src/core/service.c

@@ -2841,17 +2841,6 @@ static int service_start(Unit *u) {
         Service *s = ASSERT_PTR(SERVICE(u));
         int r;
 
-        /* We cannot fulfill this request right now, try again later
-         * please! */
-        if (IN_SET(s->state,
-                   SERVICE_STOP, SERVICE_STOP_WATCHDOG, SERVICE_STOP_SIGTERM, SERVICE_STOP_SIGKILL, SERVICE_STOP_POST,
-                   SERVICE_FINAL_WATCHDOG, SERVICE_FINAL_SIGTERM, SERVICE_FINAL_SIGKILL, SERVICE_CLEANING))
-                return -EAGAIN;
-
-        /* Already on it! */
-        if (IN_SET(s->state, SERVICE_CONDITION, SERVICE_START_PRE, SERVICE_START, SERVICE_START_POST))
-                return 0;
-
         if (s->state == SERVICE_AUTO_RESTART) {
                 /* As mentioned in unit_start(), we allow manual starts to act as "hurry up" signals
                  * for auto restart. We need to re-enqueue the job though, as the job type has changed
@@ -5426,18 +5415,25 @@ static const char* service_finished_job(Unit *u, JobType t, JobResult result) {
         return NULL;
 }
 
-static int service_can_start(Unit *u) {
+static int service_test_startable(Unit *u) {
         Service *s = ASSERT_PTR(SERVICE(u));
         int r;
 
+        /* First check the state, and do not increment start limit counter if the service cannot start due to
+         * that e.g. it is already being started. Note, the service states mapped to UNIT_ACTIVE,
+         * UNIT_RELOADING, UNIT_DEACTIVATING, UNIT_MAINTENANCE, and UNIT_REFRESHING are already filtered in
+         * unit_start(). Hence, here we only need to check states that mapped to UNIT_ACTIVATING. */
+        if (IN_SET(s->state, SERVICE_CONDITION, SERVICE_START_PRE, SERVICE_START, SERVICE_START_POST))
+                return false;
+
         /* Make sure we don't enter a busy loop of some kind. */
         r = unit_test_start_limit(u);
         if (r < 0) {
                 service_enter_dead(s, SERVICE_FAILURE_START_LIMIT_HIT, false);
                 return r;
         }
 
-        return 1;
+        return true;
 }
 
 static void service_release_resources(Unit *u) {
@@ -5695,7 +5691,7 @@ const UnitVTable service_vtable = {
                 .finished_job = service_finished_job,
         },
 
-        .can_start = service_can_start,
+        .test_startable = service_test_startable,
 
         .notify_plymouth = true,
 

src/core/socket.c

@@ -2474,25 +2474,6 @@ static int socket_start(Unit *u) {
         Socket *s = ASSERT_PTR(SOCKET(u));
         int r;
 
-        /* We cannot fulfill this request right now, try again later
-         * please! */
-        if (IN_SET(s->state,
-                   SOCKET_STOP_PRE,
-                   SOCKET_STOP_PRE_SIGKILL,
-                   SOCKET_STOP_PRE_SIGTERM,
-                   SOCKET_STOP_POST,
-                   SOCKET_FINAL_SIGTERM,
-                   SOCKET_FINAL_SIGKILL,
-                   SOCKET_CLEANING))
-                return -EAGAIN;
-
-        /* Already on it! */
-        if (IN_SET(s->state,
-                   SOCKET_START_PRE,
-                   SOCKET_START_CHOWN,
-                   SOCKET_START_POST))
-                return 0;
-
         /* Cannot run this without the service being around */
         if (UNIT_ISSET(s->service)) {
                 Service *service = ASSERT_PTR(SERVICE(UNIT_DEREF(s->service)));
@@ -3497,17 +3478,24 @@ static int socket_can_clean(Unit *u, ExecCleanMask *ret) {
         return exec_context_get_clean_mask(&s->exec_context, ret);
 }
 
-static int socket_can_start(Unit *u) {
+static int socket_test_startable(Unit *u) {
         Socket *s = ASSERT_PTR(SOCKET(u));
         int r;
 
+        /* It is already being started. */
+        if (IN_SET(s->state,
+                   SOCKET_START_PRE,
+                   SOCKET_START_CHOWN,
+                   SOCKET_START_POST))
+                return false;
+
         r = unit_test_start_limit(u);
         if (r < 0) {
                 socket_enter_dead(s, SOCKET_FAILURE_START_LIMIT_HIT);
                 return r;
         }
 
-        return 1;
+        return true;
 }
 
 static const char* const socket_exec_command_table[_SOCKET_EXEC_COMMAND_MAX] = {
@@ -3638,5 +3626,5 @@ const UnitVTable socket_vtable = {
                 },
         },
 
-        .can_start = socket_can_start,
+        .test_startable = socket_test_startable,
 };

src/core/swap.c

@@ -862,19 +862,6 @@ static int swap_start(Unit *u) {
         int r;
 
         assert(s);
-
-        /* We cannot fulfill this request right now, try again later please! */
-        if (IN_SET(s->state,
-                   SWAP_DEACTIVATING,
-                   SWAP_DEACTIVATING_SIGTERM,
-                   SWAP_DEACTIVATING_SIGKILL,
-                   SWAP_CLEANING))
-                return -EAGAIN;
-
-        /* Already on it! */
-        if (s->state == SWAP_ACTIVATING)
-                return 0;
-
         assert(IN_SET(s->state, SWAP_DEAD, SWAP_FAILED));
 
         if (detect_container() > 0)
@@ -1523,17 +1510,21 @@ static int swap_can_clean(Unit *u, ExecCleanMask *ret) {
         return exec_context_get_clean_mask(&s->exec_context, ret);
 }
 
-static int swap_can_start(Unit *u) {
+static int swap_test_startable(Unit *u) {
         Swap *s = ASSERT_PTR(SWAP(u));
         int r;
 
+        /* It is already being started. */
+        if (s->state == SWAP_ACTIVATING)
+                return false;
+
         r = unit_test_start_limit(u);
         if (r < 0) {
                 swap_enter_dead(s, SWAP_FAILURE_START_LIMIT_HIT);
                 return r;
         }
 
-        return 1;
+        return true;
 }
 
 int swap_get_priority(const Swap *s) {
@@ -1654,7 +1645,7 @@ const UnitVTable swap_vtable = {
                 },
         },
 
-        .can_start = swap_can_start,
+        .test_startable = swap_test_startable,
 
         .notify_plymouth = true,
 };

src/core/timer.c

@@ -890,7 +890,7 @@ static int timer_can_clean(Unit *u, ExecCleanMask *ret) {
         return 0;
 }
 
-static int timer_can_start(Unit *u) {
+static int timer_test_startable(Unit *u) {
         Timer *t = ASSERT_PTR(TIMER(u));
         int r;
 
@@ -900,7 +900,7 @@ static int timer_can_start(Unit *u) {
                 return r;
         }
 
-        return 1;
+        return true;
 }
 
 static void activation_details_timer_serialize(ActivationDetails *details, FILE *f) {
@@ -1077,7 +1077,7 @@ const UnitVTable timer_vtable = {
 
         .bus_set_property = bus_timer_set_property,
 
-        .can_start = timer_can_start,
+        .test_startable = timer_test_startable,
 };
 
 const ActivationDetailsVTable activation_details_timer_vtable = {

src/core/unit.c

@@ -1886,7 +1886,7 @@ int unit_start(Unit *u, ActivationDetails *details) {
         state = unit_active_state(u);
         if (UNIT_IS_ACTIVE_OR_RELOADING(state))
                 return -EALREADY;
-        if (state == UNIT_MAINTENANCE)
+        if (IN_SET(state, UNIT_DEACTIVATING, UNIT_MAINTENANCE))
                 return -EAGAIN;
 
         /* Units that aren't loaded cannot be started */
@@ -1933,10 +1933,11 @@ int unit_start(Unit *u, ActivationDetails *details) {
         if (u->freezer_state != FREEZER_RUNNING)
                 return -EDEADLK;
 
-        /* Check our ability to start early so that failure conditions don't cause us to enter a busy loop. */
-        if (UNIT_VTABLE(u)->can_start) {
-                r = UNIT_VTABLE(u)->can_start(u);
-                if (r < 0)
+        /* Check our ability to start early so that ratelimited or already starting/started units don't
+         * cause us to enter a busy loop. */
+        if (UNIT_VTABLE(u)->test_startable) {
+                r = UNIT_VTABLE(u)->test_startable(u);
+                if (r <= 0)
                         return r;
         }
 

src/core/unit.h

@@ -710,8 +710,8 @@ typedef struct UnitVTable {
         bool (*supported)(void);
 
         /* If this function is set, it's invoked first as part of starting a unit to allow start rate
-         * limiting checks to occur before we do anything else. */
-        int (*can_start)(Unit *u);
+         * limiting checks and unit state checks to occur before we do anything else. */
+        int (*test_startable)(Unit *u);
 
         /* Returns > 0 if the whole subsystem is ratelimited, and new start operations should not be started
          * for this unit type right now. */

test/units/TEST-07-PID1.start-limit.sh

@@ -0,0 +1,46 @@
+#!/usr/bin/env bash
+# SPDX-License-Identifier: LGPL-2.1-or-later
+set -eux
+set -o pipefail
+
+# For issue #39247.
+
+at_exit() {
+    set +e
+
+    rm -rf /run/systemd/system/systemd-resolved.service.d/
+    systemctl daemon-reload
+    systemctl restart systemd-resolved.service
+}
+
+trap at_exit EXIT
+
+mkdir -p /run/systemd/system/systemd-resolved.service.d/
+cat >/run/systemd/system/systemd-resolved.service.d/99-start-limit.conf <<EOF
+[Unit]
+StartLimitBurst=5
+StartLimitInterval=100
+
+[Service]
+ExecStopPost=sleep 10
+EOF
+
+systemctl daemon-reload
+systemctl restart systemd-resolved.service
+systemctl reset-failed systemd-resolved.service
+systemctl status --no-pager systemd-resolved.service
+systemctl show systemd-resolved.service | grep StartLimit
+
+for i in {1..5}; do
+    echo "Start #$i"
+
+    systemctl stop --no-block systemd-resolved.service
+    # Wait for systemd-resolved in ExecStart= being stopped.
+    # shellcheck disable=SC2016
+    timeout 10 bash -c 'until [[ "$(systemctl show --property=MainPID --value systemd-resolved.service)" == 0 ]]; do sleep 0.1; done'
+    if ! resolvectl; then
+        journalctl -o short-monotonic --no-hostname --no-pager -u systemd-resolved.service -n 15
+        exit 1
+    fi
+    systemctl is-active systemd-resolved.service
+done