core: add support for the "pids" cgroup controller

This adds support for the new "pids" cgroup controller of 4.3 kernels.
It allows accounting the number of tasks in a cgroup and enforcing
limits on it.

This adds two new setting TasksAccounting= and TasksMax= to each unit,
as well as a gloabl option DefaultTasksAccounting=.

This also updated "cgtop" to optionally make use of the new
kernel-provided accounting.

systemctl has been updated to show the number of tasks for each service
if it is available.

This patch also adds correct support for undoing memory limits for units
using a MemoryLimit=infinity syntax. We do the same for TasksMax= now
and hence keep things in sync here.

1 files changed, 55 insertions, 37 deletions

diff --git a/src/systemctl/systemctl.c b/src/systemctl/systemctl.c
index 40b366c7a5..10835b81bf 100644
--- a/src/systemctl/systemctl.c
+++ b/src/systemctl/systemctl.c
@@ -20,59 +20,60 @@
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 ***/
 
-#include <sys/reboot.h>
-#include <linux/reboot.h>
-#include <stdio.h>
+#include <errno.h>
+#include <fcntl.h>
 #include <getopt.h>
+#include <linux/reboot.h>
 #include <locale.h>
 #include <stdbool.h>
+#include <stddef.h>
+#include <stdio.h>
 #include <string.h>
-#include <errno.h>
-#include <unistd.h>
-#include <fcntl.h>
+#include <sys/reboot.h>
 #include <sys/socket.h>
-#include <stddef.h>
+#include <unistd.h>
 
+#include "sd-bus.h"
 #include "sd-daemon.h"
 #include "sd-login.h"
-#include "sd-bus.h"
-#include "log.h"
-#include "util.h"
-#include "macro.h"
-#include "set.h"
-#include "utmp-wtmp.h"
-#include "special.h"
-#include "initreq.h"
-#include "path-util.h"
-#include "strv.h"
+
+#include "build.h"
+#include "bus-common-errors.h"
+#include "bus-error.h"
+#include "bus-message.h"
+#include "bus-util.h"
 #include "cgroup-show.h"
 #include "cgroup-util.h"
-#include "list.h"
-#include "path-lookup.h"
-#include "exit-status.h"
-#include "build.h"
-#include "unit-name.h"
-#include "pager.h"
-#include "spawn-ask-password-agent.h"
-#include "spawn-polkit-agent.h"
-#include "install.h"
-#include "logs-show.h"
-#include "socket-util.h"
-#include "fileio.h"
 #include "copy.h"
-#include "env-util.h"
-#include "bus-util.h"
-#include "bus-message.h"
-#include "bus-error.h"
-#include "bus-common-errors.h"
-#include "mkdir.h"
 #include "dropin.h"
 #include "efivars.h"
+#include "env-util.h"
+#include "exit-status.h"
+#include "fileio.h"
 #include "formats-util.h"
-#include "process-util.h"
-#include "terminal-util.h"
 #include "hostname-util.h"
+#include "initreq.h"
+#include "install.h"
+#include "list.h"
+#include "log.h"
+#include "logs-show.h"
+#include "macro.h"
+#include "mkdir.h"
+#include "pager.h"
+#include "path-lookup.h"
+#include "path-util.h"
+#include "process-util.h"
+#include "set.h"
 #include "signal-util.h"
+#include "socket-util.h"
+#include "spawn-ask-password-agent.h"
+#include "spawn-polkit-agent.h"
+#include "special.h"
+#include "strv.h"
+#include "terminal-util.h"
+#include "unit-name.h"
+#include "util.h"
+#include "utmp-wtmp.h"
 
 static char **arg_types = NULL;
 static char **arg_states = NULL;
@@ -3285,6 +3286,8 @@ typedef struct UnitStatusInfo {
         uint64_t memory_current;
         uint64_t memory_limit;
         uint64_t cpu_usage_nsec;
+        uint64_t tasks_current;
+        uint64_t tasks_max;
 
         LIST_HEAD(ExecStatusInfo, exec);
 } UnitStatusInfo;
@@ -3543,6 +3546,15 @@ static void print_status_info(
         if (i->status_errno > 0)
                 printf("    Error: %i (%s)\n", i->status_errno, strerror(i->status_errno));
 
+        if (i->tasks_current != (uint64_t) -1) {
+                printf("    Tasks: %" PRIu64, i->tasks_current);
+
+                if (i->tasks_max != (uint64_t) -1)
+                        printf(" (limit: %" PRIi64 ")\n", i->tasks_max);
+                else
+                        printf("\n");
+        }
+
         if (i->memory_current != (uint64_t) -1) {
                 char buf[FORMAT_BYTES_MAX];
 
@@ -3776,6 +3788,10 @@ static int status_property(const char *name, sd_bus_message *m, UnitStatusInfo *
                         i->memory_current = u;
                 else if (streq(name, "MemoryLimit"))
                         i->memory_limit = u;
+                else if (streq(name, "TasksCurrent"))
+                        i->tasks_current = u;
+                else if (streq(name, "TasksMax"))
+                        i->tasks_max = u;
                 else if (streq(name, "CPUUsageNSec"))
                         i->cpu_usage_nsec = u;
 
@@ -4252,6 +4268,8 @@ static int show_one(
                 .memory_current = (uint64_t) -1,
                 .memory_limit = (uint64_t) -1,
                 .cpu_usage_nsec = (uint64_t) -1,
+                .tasks_current = (uint64_t) -1,
+                .tasks_max = (uint64_t) -1,
         };
         ExecStatusInfo *p;
         int r;