Use a dash-truncated drop-in for user-%j.slice configuration

This removes the UserTasksMax= setting in logind.conf. Instead, the generic
TasksMax= setting on the slice should be used. Instead of a transient unit we
use a drop-in to tweak the default definition of a .slice. It's better to use
the normal unit mechanisms instead of creating units on the fly. This will also
make it easier to start user@.service independently of logind, or set
additional settings like MemoryMax= for user slices.

The setting in logind is removed, because otherwise we would have two sources
of "truth": the slice on disk and the logind config. Instead of trying to
coordinate those two sources of configuration (and maintainer overrides to
both), let's just convert to the new one fully.

Right now now automatic transition mechanism is provided. logind will emit a
hint when it encounters the setting, but otherwise it will be ignored.

Fixes #2556.

6 files changed, 50 insertions, 99 deletions

diff --git a/src/login/logind-dbus.c b/src/login/logind-dbus.c
index d92437b67f..7078e67dd4 100644
--- a/src/login/logind-dbus.c
+++ b/src/login/logind-dbus.c
@@ -332,6 +332,20 @@ static int property_get_current_inhibitors(
         return sd_bus_message_append(reply, "t", (uint64_t) hashmap_size(m->inhibitors));
 }
 
+static int property_get_compat_user_tasks_max(
+                sd_bus *bus,
+                const char *path,
+                const char *interface,
+                const char *property,
+                sd_bus_message *reply,
+                void *userdata,
+                sd_bus_error *error) {
+
+        assert(reply);
+
+        return sd_bus_message_append(reply, "t", CGROUP_LIMIT_MAX);
+}
+
 static int method_get_session(sd_bus_message *message, void *userdata, sd_bus_error *error) {
         _cleanup_free_ char *p = NULL;
         Manager *m = userdata;
@@ -2720,7 +2734,7 @@ const sd_bus_vtable manager_vtable[] = {
         SD_BUS_PROPERTY("NCurrentInhibitors", "t", property_get_current_inhibitors, 0, 0),
         SD_BUS_PROPERTY("SessionsMax", "t", NULL, offsetof(Manager, sessions_max), SD_BUS_VTABLE_PROPERTY_CONST),
         SD_BUS_PROPERTY("NCurrentSessions", "t", property_get_current_sessions, 0, 0),
-        SD_BUS_PROPERTY("UserTasksMax", "t", NULL, offsetof(Manager, user_tasks_max), SD_BUS_VTABLE_PROPERTY_CONST),
+        SD_BUS_PROPERTY("UserTasksMax", "t", property_get_compat_user_tasks_max, 0, SD_BUS_VTABLE_PROPERTY_CONST|SD_BUS_VTABLE_HIDDEN),
 
         SD_BUS_METHOD("GetSession", "s", "o", method_get_session, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("GetSessionByPID", "u", "o", method_get_session_by_pid, SD_BUS_VTABLE_UNPRIVILEGED),
diff --git a/src/login/logind-gperf.gperf b/src/login/logind-gperf.gperf
index f6f57526f6..c85339dcd3 100644
--- a/src/login/logind-gperf.gperf
+++ b/src/login/logind-gperf.gperf
@@ -17,27 +17,27 @@ struct ConfigPerfItem;
 %struct-type
 %includes
 %%
-Login.NAutoVTs,                    config_parse_n_autovts,     0, offsetof(Manager, n_autovts)
-Login.ReserveVT,                   config_parse_unsigned,      0, offsetof(Manager, reserve_vt)
-Login.KillUserProcesses,           config_parse_bool,          0, offsetof(Manager, kill_user_processes)
-Login.KillOnlyUsers,               config_parse_strv,          0, offsetof(Manager, kill_only_users)
-Login.KillExcludeUsers,            config_parse_strv,          0, offsetof(Manager, kill_exclude_users)
-Login.InhibitDelayMaxSec,          config_parse_sec,           0, offsetof(Manager, inhibit_delay_max)
-Login.HandlePowerKey,              config_parse_handle_action, 0, offsetof(Manager, handle_power_key)
-Login.HandleSuspendKey,            config_parse_handle_action, 0, offsetof(Manager, handle_suspend_key)
-Login.HandleHibernateKey,          config_parse_handle_action, 0, offsetof(Manager, handle_hibernate_key)
-Login.HandleLidSwitch,             config_parse_handle_action, 0, offsetof(Manager, handle_lid_switch)
-Login.HandleLidSwitchExternalPower,config_parse_handle_action, 0, offsetof(Manager, handle_lid_switch_ep)
-Login.HandleLidSwitchDocked,       config_parse_handle_action, 0, offsetof(Manager, handle_lid_switch_docked)
-Login.PowerKeyIgnoreInhibited,     config_parse_bool,          0, offsetof(Manager, power_key_ignore_inhibited)
-Login.SuspendKeyIgnoreInhibited,   config_parse_bool,          0, offsetof(Manager, suspend_key_ignore_inhibited)
-Login.HibernateKeyIgnoreInhibited, config_parse_bool,          0, offsetof(Manager, hibernate_key_ignore_inhibited)
-Login.LidSwitchIgnoreInhibited,    config_parse_bool,          0, offsetof(Manager, lid_switch_ignore_inhibited)
-Login.HoldoffTimeoutSec,           config_parse_sec,           0, offsetof(Manager, holdoff_timeout_usec)
-Login.IdleAction,                  config_parse_handle_action, 0, offsetof(Manager, idle_action)
-Login.IdleActionSec,               config_parse_sec,           0, offsetof(Manager, idle_action_usec)
-Login.RuntimeDirectorySize,        config_parse_tmpfs_size,    0, offsetof(Manager, runtime_dir_size)
-Login.RemoveIPC,                   config_parse_bool,          0, offsetof(Manager, remove_ipc)
-Login.InhibitorsMax,               config_parse_uint64,        0, offsetof(Manager, inhibitors_max)
-Login.SessionsMax,                 config_parse_uint64,        0, offsetof(Manager, sessions_max)
-Login.UserTasksMax,                config_parse_user_tasks_max,0, offsetof(Manager, user_tasks_max)
+Login.NAutoVTs,                     config_parse_n_autovts,             0, offsetof(Manager, n_autovts)
+Login.ReserveVT,                    config_parse_unsigned,              0, offsetof(Manager, reserve_vt)
+Login.KillUserProcesses,            config_parse_bool,                  0, offsetof(Manager, kill_user_processes)
+Login.KillOnlyUsers,                config_parse_strv,                  0, offsetof(Manager, kill_only_users)
+Login.KillExcludeUsers,             config_parse_strv,                  0, offsetof(Manager, kill_exclude_users)
+Login.InhibitDelayMaxSec,           config_parse_sec,                   0, offsetof(Manager, inhibit_delay_max)
+Login.HandlePowerKey,               config_parse_handle_action,         0, offsetof(Manager, handle_power_key)
+Login.HandleSuspendKey,             config_parse_handle_action,         0, offsetof(Manager, handle_suspend_key)
+Login.HandleHibernateKey,           config_parse_handle_action,         0, offsetof(Manager, handle_hibernate_key)
+Login.HandleLidSwitch,              config_parse_handle_action,         0, offsetof(Manager, handle_lid_switch)
+Login.HandleLidSwitchExternalPower, config_parse_handle_action,         0, offsetof(Manager, handle_lid_switch_ep)
+Login.HandleLidSwitchDocked,        config_parse_handle_action,         0, offsetof(Manager, handle_lid_switch_docked)
+Login.PowerKeyIgnoreInhibited,      config_parse_bool,                  0, offsetof(Manager, power_key_ignore_inhibited)
+Login.SuspendKeyIgnoreInhibited,    config_parse_bool,                  0, offsetof(Manager, suspend_key_ignore_inhibited)
+Login.HibernateKeyIgnoreInhibited,  config_parse_bool,                  0, offsetof(Manager, hibernate_key_ignore_inhibited)
+Login.LidSwitchIgnoreInhibited,     config_parse_bool,                  0, offsetof(Manager, lid_switch_ignore_inhibited)
+Login.HoldoffTimeoutSec,            config_parse_sec,                   0, offsetof(Manager, holdoff_timeout_usec)
+Login.IdleAction,                   config_parse_handle_action,         0, offsetof(Manager, idle_action)
+Login.IdleActionSec,                config_parse_sec,                   0, offsetof(Manager, idle_action_usec)
+Login.RuntimeDirectorySize,         config_parse_tmpfs_size,            0, offsetof(Manager, runtime_dir_size)
+Login.RemoveIPC,                    config_parse_bool,                  0, offsetof(Manager, remove_ipc)
+Login.InhibitorsMax,                config_parse_uint64,                0, offsetof(Manager, inhibitors_max)
+Login.SessionsMax,                  config_parse_uint64,                0, offsetof(Manager, sessions_max)
+Login.UserTasksMax,                 config_parse_compat_user_tasks_max, 0, offsetof(Manager, user_tasks_max)
diff --git a/src/login/logind-user.c b/src/login/logind-user.c
index 379d8d0cdd..01b602dbc4 100644
--- a/src/login/logind-user.c
+++ b/src/login/logind-user.c
@@ -368,36 +368,6 @@ fail:
         return r;
 }
 
-static int user_start_slice(User *u) {
-        _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
-        const char *description;
-        char *job;
-        int r;
-
-        assert(u);
-
-        u->slice_job = mfree(u->slice_job);
-        description = strjoina("User Slice of ", u->name);
-
-        r = manager_start_slice(
-                        u->manager,
-                        u->slice,
-                        description,
-                        "systemd-logind.service",
-                        "systemd-user-sessions.service",
-                        u->manager->user_tasks_max,
-                        &error,
-                        &job);
-        if (r >= 0)
-                u->slice_job = job;
-        else if (!sd_bus_error_has_name(&error, BUS_ERROR_UNIT_EXISTS))
-                /* we don't fail due to this, let's try to continue */
-                log_error_errno(r, "Failed to start user slice %s, ignoring: %s (%s)",
-                                u->slice, bus_error_message(&error, r), error.name);
-
-        return 0;
-}
-
 static int user_start_service(User *u) {
         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
         char *job;
@@ -453,11 +423,6 @@ int user_start(User *u) {
                         return r;
         }
 
-        /* Create cgroup */
-        r = user_start_slice(u);
-        if (r < 0)
-                return r;
-
         /* Save the user data so far, because pam_systemd will read the
          * XDG_RUNTIME_DIR out of it while starting up systemd --user.
          * We need to do user_save_internal() because we have not
@@ -858,8 +823,8 @@ int config_parse_tmpfs_size(
         return 0;
 }
 
-int config_parse_user_tasks_max(
-                const char* unit,
+int config_parse_compat_user_tasks_max(
+                const char *unit,
                 const char *filename,
                 unsigned line,
                 const char *section,
@@ -870,45 +835,17 @@ int config_parse_user_tasks_max(
                 void *data,
                 void *userdata) {
 
-        uint64_t *m = data;
-        uint64_t k;
-        int r;
-
         assert(filename);
         assert(lvalue);
         assert(rvalue);
         assert(data);
 
-        if (isempty(rvalue)) {
-                *m = system_tasks_max_scale(DEFAULT_USER_TASKS_MAX_PERCENTAGE, 100U);
-                return 0;
-        }
-
-        if (streq(rvalue, "infinity")) {
-                *m = CGROUP_LIMIT_MAX;
-                return 0;
-        }
-
-        /* Try to parse as percentage */
-        r = parse_percent(rvalue);
-        if (r >= 0)
-                k = system_tasks_max_scale(r, 100U);
-        else {
-
-                /* If the passed argument was not a percentage, or out of range, parse as byte size */
-
-                r = safe_atou64(rvalue, &k);
-                if (r < 0) {
-                        log_syntax(unit, LOG_ERR, filename, line, r, "Failed to parse tasks maximum, ignoring: %s", rvalue);
-                        return 0;
-                }
-        }
-
-        if (k <= 0 || k >= UINT64_MAX) {
-                log_syntax(unit, LOG_ERR, filename, line, 0, "Tasks maximum out of range, ignoring: %s", rvalue);
-                return 0;
-        }
-
-        *m = k;
+        log_syntax(unit, LOG_NOTICE, filename, line, 0,
+                   "Support for option %s= has been removed.",
+                   lvalue);
+        log_info("Hint: try creating /etc/systemd/system/user-.slice/50-limits.conf with:\n"
+                 "        [Slice]\n"
+                 "        TasksMax=%s",
+                 rvalue);
         return 0;
 }
diff --git a/src/login/logind-user.h b/src/login/logind-user.h
index d95059d5a9..18a80b3fdf 100644
--- a/src/login/logind-user.h
+++ b/src/login/logind-user.h
@@ -79,3 +79,5 @@ UserState user_state_from_string(const char *s) _pure_;
 
 int bus_user_method_terminate(sd_bus_message *message, void *userdata, sd_bus_error *error);
 int bus_user_method_kill(sd_bus_message *message, void *userdata, sd_bus_error *error);
+
+int config_parse_compat_user_tasks_max(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
diff --git a/src/login/logind.conf.in b/src/login/logind.conf.in
index 40a77dc7be..1029e29bc7 100644
--- a/src/login/logind.conf.in
+++ b/src/login/logind.conf.in
@@ -35,4 +35,3 @@
 #RemoveIPC=yes
 #InhibitorsMax=8192
 #SessionsMax=8192
-#UserTasksMax=33%
diff --git a/src/login/logind.h b/src/login/logind.h
index be2963c256..7470516fba 100644
--- a/src/login/logind.h
+++ b/src/login/logind.h
@@ -182,7 +182,6 @@ int manager_set_lid_switch_ignore(Manager *m, usec_t until);
 
 int config_parse_n_autovts(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
 int config_parse_tmpfs_size(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
-int config_parse_user_tasks_max(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
 
 int manager_get_session_from_creds(Manager *m, sd_bus_message *message, const char *name, sd_bus_error *error, Session **ret);
 int manager_get_user_from_creds(Manager *m, sd_bus_message *message, uid_t uid, sd_bus_error *error, User **ret);