chiark / gitweb /
use CLOEXEC flags instead of fcntl()
[elogind.git] / udev / udevd.c
index 405a1ed9071290dd13ffbb1d0ea81fe1fd911dc1..88e117f50a1f46807688aeafebaaa4e7295510e9 100644 (file)
@@ -1,6 +1,8 @@
 /*
- * Copyright (C) 2004-2008 Kay Sievers <kay.sievers@vrfy.org>
+ * Copyright (C) 2004-2009 Kay Sievers <kay.sievers@vrfy.org>
  * Copyright (C) 2004 Chris Friesen <chris_friesen@sympatico.ca>
+ * Copyright (C) 2009 Canonical Ltd.
+ * Copyright (C) 2009 Scott James Remnant <scott@netsplit.com>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
 #include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <stdbool.h>
 #include <string.h>
 #include <ctype.h>
 #include <fcntl.h>
 #include <time.h>
 #include <getopt.h>
+#include <dirent.h>
+#include <sys/time.h>
+#include <sys/prctl.h>
+#include <sys/socket.h>
+#include <sys/signalfd.h>
 #include <sys/select.h>
+#include <sys/poll.h>
 #include <sys/wait.h>
 #include <sys/stat.h>
 #include <sys/ioctl.h>
-#ifdef HAVE_INOTIFY
 #include <sys/inotify.h>
-#endif
 
 #include "udev.h"
 
 #define UDEVD_PRIORITY                 -4
 #define UDEV_PRIORITY                  -2
 
-/* maximum limit of forked childs */
-#define UDEVD_MAX_CHILDS               256
-
-static int debug;
+static bool debug;
 
 static void log_fn(struct udev *udev, int priority,
                   const char *file, int line, const char *fn,
                   const char *format, va_list args)
 {
        if (debug) {
-               fprintf(stderr, "[%d] %s: ", (int) getpid(), fn);
-               vfprintf(stderr, format, args);
+               char buf[1024];
+               struct timeval tv;
+               struct timezone tz;
+
+               vsnprintf(buf, sizeof(buf), format, args);
+               gettimeofday(&tv, &tz);
+               fprintf(stderr, "%llu.%06u [%u] %s: %s",
+                       (unsigned long long) tv.tv_sec, (unsigned int) tv.tv_usec,
+                       (int) getpid(), fn, buf);
        } else {
                vsyslog(priority, format, args);
        }
 }
 
-static int debug_trace;
+static bool debug_trace;
 static struct udev_rules *rules;
+static struct udev_queue_export *udev_queue_export;
 static struct udev_ctrl *udev_ctrl;
-static struct udev_monitor *kernel_monitor;
-static int inotify_fd = -1;
-static int signal_pipe[2] = {-1, -1};
-static volatile int sigchilds_waiting;
-static volatile int udev_exit;
-static volatile int reload_config;
-static int run_exec_q;
-static int stop_exec_q;
+static struct udev_monitor *monitor;
+static int worker_watch[2];
+static pid_t settle_pid;
+static bool stop_exec_queue;
+static bool reload_config;
 static int max_childs;
 static int childs;
+static sigset_t orig_sigmask;
 static struct udev_list_node event_list;
+static struct udev_list_node worker_list;
+static bool udev_exit;
+static volatile sig_atomic_t worker_exit;
+
+enum poll_fd {
+       FD_CONTROL,
+       FD_NETLINK,
+       FD_INOTIFY,
+       FD_SIGNAL,
+       FD_WORKER,
+};
+
+static struct pollfd pfd[] = {
+       [FD_NETLINK] = { .events = POLLIN },
+       [FD_WORKER] =  { .events = POLLIN },
+       [FD_SIGNAL] =  { .events = POLLIN },
+       [FD_INOTIFY] = { .events = POLLIN },
+       [FD_CONTROL] = { .events = POLLIN },
+};
 
 enum event_state {
+       EVENT_UNDEF,
        EVENT_QUEUED,
-       EVENT_FINISHED,
-       EVENT_FAILED,
+       EVENT_RUNNING,
+};
+
+struct event {
+       struct udev_list_node node;
+       struct udev *udev;
+       struct udev_device *dev;
+       enum event_state state;
+       int exitcode;
+       unsigned long long int delaying_seqnum;
+       unsigned long long int seqnum;
+       const char *devpath;
+       size_t devpath_len;
+       const char *devpath_old;
+       dev_t devnum;
+       bool is_block;
 };
 
-static struct udev_event *node_to_event(struct udev_list_node *node)
+static struct event *node_to_event(struct udev_list_node *node)
 {
        char *event;
 
        event = (char *)node;
-       event -= offsetof(struct udev_event, node);
-       return (struct udev_event *)event;
+       event -= offsetof(struct event, node);
+       return (struct event *)event;
 }
 
-static void export_event_state(struct udev_event *event, enum event_state state)
-{
-       char filename[UTIL_PATH_SIZE];
-       char filename_failed[UTIL_PATH_SIZE];
-       size_t start;
-
-       /* location of queue file */
-       snprintf(filename, sizeof(filename), "%s/.udev/queue/%llu",
-                udev_get_dev_path(event->udev), udev_device_get_seqnum(event->dev));
-
-       /* location of failed file */
-       util_strlcpy(filename_failed, udev_get_dev_path(event->udev), sizeof(filename_failed));
-       util_strlcat(filename_failed, "/", sizeof(filename_failed));
-       start = util_strlcat(filename_failed, ".udev/failed/", sizeof(filename_failed));
-       util_strlcat(filename_failed, udev_device_get_devpath(event->dev), sizeof(filename_failed));
-       util_path_encode(&filename_failed[start], sizeof(filename_failed) - start);
-
-       switch (state) {
-       case EVENT_QUEUED:
-               if(unlink(filename_failed) == 0)
-                       util_delete_path(event->udev, filename_failed);
-               util_create_path(event->udev, filename);
-               udev_selinux_setfscreatecon(event->udev, filename, S_IFLNK);
-               symlink(udev_device_get_devpath(event->dev), filename);
-               udev_selinux_resetfscreatecon(event->udev);
-               break;
-       case EVENT_FINISHED:
-               if (udev_device_get_devpath_old(event->dev) != NULL) {
-                       /* "move" event - rename failed file to current name, do not delete failed */
-                       char filename_failed_old[UTIL_PATH_SIZE];
-
-                       util_strlcpy(filename_failed_old, udev_get_dev_path(event->udev), sizeof(filename_failed_old));
-                       util_strlcat(filename_failed_old, "/", sizeof(filename_failed_old));
-                       start = util_strlcat(filename_failed_old, ".udev/failed/", sizeof(filename_failed_old));
-                       util_strlcat(filename_failed_old, udev_device_get_devpath_old(event->dev), sizeof(filename_failed_old));
-                       util_path_encode(&filename_failed_old[start], sizeof(filename) - start);
-
-                       if (rename(filename_failed_old, filename_failed) == 0)
-                               info(event->udev, "renamed devpath, moved failed state of '%s' to %s'\n",
-                                    udev_device_get_devpath_old(event->dev), udev_device_get_devpath(event->dev));
-               } else {
-                       if (unlink(filename_failed) == 0)
-                               util_delete_path(event->udev, filename_failed);
-               }
+enum worker_state {
+       WORKER_UNDEF,
+       WORKER_RUNNING,
+       WORKER_IDLE,
+       WORKER_KILLED,
+};
 
-               unlink(filename);
+struct worker {
+       struct udev_list_node node;
+       struct udev *udev;
+       int refcount;
+       pid_t pid;
+       struct udev_monitor *monitor;
+       enum worker_state state;
+       struct event *event;
+};
 
-               /* clean up possibly empty queue directory */
-               if (udev_list_is_empty(&event_list))
-                       util_delete_path(event->udev, filename);
-               break;
-       case EVENT_FAILED:
-               /* move failed event to the failed directory */
-               util_create_path(event->udev, filename_failed);
-               rename(filename, filename_failed);
-
-               /* clean up possibly empty queue directory */
-               if (udev_list_is_empty(&event_list))
-                       util_delete_path(event->udev, filename);
-               break;
-       }
+/* passed from worker to main process */
+struct worker_message {
+       pid_t pid;
+       int exitcode;
+};
+
+static struct worker *node_to_worker(struct udev_list_node *node)
+{
+       char *worker;
 
-       return;
+       worker = (char *)node;
+       worker -= offsetof(struct worker, node);
+       return (struct worker *)worker;
 }
 
-static void event_queue_delete(struct udev_event *event)
+static void event_queue_delete(struct event *event)
 {
        udev_list_node_remove(&event->node);
 
        /* mark as failed, if "add" event returns non-zero */
-       if (event->exitstatus && strcmp(udev_device_get_action(event->dev), "add") == 0)
-               export_event_state(event, EVENT_FAILED);
+       if (event->exitcode != 0 && strcmp(udev_device_get_action(event->dev), "add") == 0)
+               udev_queue_export_device_failed(udev_queue_export, event->dev);
        else
-               export_event_state(event, EVENT_FINISHED);
+               udev_queue_export_device_finished(udev_queue_export, event->dev);
 
+       info(event->udev, "seq %llu done with %i\n", udev_device_get_seqnum(event->dev), event->exitcode);
        udev_device_unref(event->dev);
-       udev_event_unref(event);
+       free(event);
+}
+
+static void event_sig_handler(int signum)
+{
+       switch (signum) {
+       case SIGALRM:
+               _exit(1);
+               break;
+       case SIGTERM:
+               worker_exit = true;
+               break;
+       }
 }
 
-static void asmlinkage event_sig_handler(int signum)
+static struct worker *worker_ref(struct worker *worker)
 {
-       if (signum == SIGALRM)
-               exit(1);
+       worker->refcount++;
+       return worker;
 }
 
-static void event_fork(struct udev_event *event)
+static void worker_unref(struct worker *worker)
 {
+       worker->refcount--;
+       if (worker->refcount > 0)
+               return;
+
+       udev_list_node_remove(&worker->node);
+       udev_monitor_unref(worker->monitor);
+       childs--;
+       info(worker->udev, "worker [%u] cleaned up\n", worker->pid);
+       free(worker);
+}
+
+static void worker_new(struct event *event)
+{
+       struct worker *worker;
+       struct udev_monitor *worker_monitor;
        pid_t pid;
        struct sigaction act;
-       int err;
 
-       if (debug_trace) {
-               event->trace = 1;
-               fprintf(stderr, "fork %s (%llu)\n",
-                      udev_device_get_syspath(event->dev),
-                      udev_device_get_seqnum(event->dev));
-       }
+       /* listen for new events */
+       worker_monitor = udev_monitor_new_from_netlink(event->udev, NULL);
+       if (worker_monitor == NULL)
+               return;
+       /* allow the main daemon netlink address to send devices to the worker */
+       udev_monitor_allow_unicast_sender(worker_monitor, monitor);
+       udev_monitor_enable_receiving(worker_monitor);
+
+       worker = calloc(1, sizeof(struct worker));
+       if (worker == NULL)
+               return;
+       /* worker + event reference */
+       worker->refcount = 2;
+       worker->udev = event->udev;
 
        pid = fork();
        switch (pid) {
-       case 0:
-               /* child */
-               udev_monitor_unref(kernel_monitor);
+       case 0: {
+               sigset_t sigmask;
+               struct udev_device *dev;
+               struct pollfd pmon = {
+                       .fd = udev_monitor_get_fd(worker_monitor),
+                       .events = POLLIN,
+               };
+
+               udev_queue_export_unref(udev_queue_export);
+               udev_monitor_unref(monitor);
                udev_ctrl_unref(udev_ctrl);
-               if (inotify_fd >= 0)
-                       close(inotify_fd);
-               close(signal_pipe[READ_END]);
-               close(signal_pipe[WRITE_END]);
-               logging_close();
-               logging_init("udevd-event");
+               close(pfd[FD_SIGNAL].fd);
+               close(worker_watch[READ_END]);
+               udev_log_close();
+               udev_log_init("udevd-work");
                setpriority(PRIO_PROCESS, 0, UDEV_PRIORITY);
 
                /* set signal handlers */
                memset(&act, 0x00, sizeof(act));
-               act.sa_handler = (void (*)(int)) event_sig_handler;
+               act.sa_handler = event_sig_handler;
                sigemptyset (&act.sa_mask);
                act.sa_flags = 0;
+               sigaction(SIGTERM, &act, NULL);
                sigaction(SIGALRM, &act, NULL);
 
-               /* reset to default */
-               act.sa_handler = SIG_DFL;
-               sigaction(SIGINT, &act, NULL);
-               sigaction(SIGTERM, &act, NULL);
-               sigaction(SIGCHLD, &act, NULL);
-               sigaction(SIGHUP, &act, NULL);
+               /* unblock SIGALRM */
+               sigfillset(&sigmask);
+               sigdelset(&sigmask, SIGALRM);
+               sigprocmask(SIG_SETMASK, &sigmask, NULL);
+               /* SIGTERM is unblocked in ppoll() */
+               sigdelset(&sigmask, SIGTERM);
+
+               /* request TERM signal if parent exits */
+               prctl(PR_SET_PDEATHSIG, SIGTERM);
 
-               /* set timeout to prevent hanging processes */
-               alarm(UDEV_EVENT_TIMEOUT);
+               /* initial device */
+               dev = event->dev;
 
-               /* apply rules, create node, symlinks */
-               err = udev_event_execute_rules(event, rules);
+               do {
+                       struct udev_event *udev_event;
+                       struct worker_message msg = {};
+                       int err;
+                       int failed = 0;
 
-               /* rules may change/disable the timeout */
-               if (udev_device_get_event_timeout(event->dev) >= 0)
-                       alarm(udev_device_get_event_timeout(event->dev));
+                       info(event->udev, "seq %llu running\n", udev_device_get_seqnum(dev));
+                       udev_event = udev_event_new(dev);
+                       if (udev_event == NULL)
+                               _exit(3);
 
-               /* execute RUN= */
-               if (err == 0 && !event->ignore_device && udev_get_run(event->udev))
-                       udev_event_execute_run(event);
+                       /* set timeout to prevent hanging processes */
+                       alarm(UDEV_EVENT_TIMEOUT);
 
-               info(event->udev, "seq %llu exit with %i\n", udev_device_get_seqnum(event->dev), err);
-               logging_close();
-               if (err != 0)
-                       exit(1);
+                       /* apply rules, create node, symlinks */
+                       err = udev_event_execute_rules(udev_event, rules);
+
+                       /* rules may change/disable the timeout */
+                       if (udev_device_get_event_timeout(dev) >= 0)
+                               alarm(udev_device_get_event_timeout(dev));
+
+                       /* execute RUN= */
+                       if (err == 0 && !udev_event->ignore_device && udev_get_run(udev_event->udev))
+                               failed = udev_event_execute_run(udev_event,
+                                                               &orig_sigmask);
+
+                       /* reset alarm */
+                       alarm(0);
+
+                       /* apply/restore inotify watch */
+                       if (err == 0 && udev_event->inotify_watch) {
+                               udev_watch_begin(udev_event->udev, dev);
+                               udev_device_update_db(dev);
+                       }
+
+                       /* send processed event back to libudev listeners */
+                       udev_monitor_send_device(worker_monitor, NULL, dev);
+
+                       /* send back the result of the event execution */
+                       if (err != 0)
+                               msg.exitcode = err;
+                       else if (failed != 0)
+                               msg.exitcode = failed;
+                       msg.pid = getpid();
+                       send(worker_watch[WRITE_END], &msg, sizeof(struct worker_message), 0);
+
+                       info(event->udev, "seq %llu processed with %i\n", udev_device_get_seqnum(dev), err);
+                       udev_event_unref(udev_event);
+                       udev_device_unref(dev);
+                       dev = NULL;
+
+                       /* wait for more device messages or signal from udevd */
+                       while (!worker_exit) {
+                               int fdcount;
+
+                               fdcount = ppoll(&pmon, 1, NULL, &sigmask);
+                               if (fdcount < 0)
+                                       continue;
+
+                               if (pmon.revents & POLLIN) {
+                                       dev = udev_monitor_receive_device(worker_monitor);
+                                       if (dev != NULL)
+                                               break;
+                               }
+                       }
+               } while (dev != NULL);
+
+               udev_monitor_unref(worker_monitor);
+               udev_log_close();
                exit(0);
+       }
        case -1:
+               udev_monitor_unref(worker_monitor);
+               event->state = EVENT_QUEUED;
+               free(worker);
                err(event->udev, "fork of child failed: %m\n");
-               event_queue_delete(event);
                break;
        default:
-               /* get SIGCHLD in main loop */
-               info(event->udev, "seq %llu forked, pid [%d], '%s' '%s', %ld seconds old\n",
-                    udev_device_get_seqnum(event->dev),
-                    pid,
-                    udev_device_get_action(event->dev),
-                    udev_device_get_subsystem(event->dev),
-                    time(NULL) - event->queue_time);
-               event->pid = pid;
+               /* close monitor, but keep address around */
+               udev_monitor_disconnect(worker_monitor);
+               worker->monitor = worker_monitor;
+               worker->pid = pid;
+               worker->state = WORKER_RUNNING;
+               worker->event = event;
+               event->state = EVENT_RUNNING;
+               udev_list_node_append(&worker->node, &worker_list);
                childs++;
+               info(event->udev, "seq %llu forked new worker [%u]\n", udev_device_get_seqnum(event->dev), pid);
+               break;
        }
 }
 
-static void event_queue_insert(struct udev_event *event)
+static void event_run(struct event *event)
 {
-       char filename[UTIL_PATH_SIZE];
-       int fd;
+       struct udev_list_node *loop;
 
-       event->queue_time = time(NULL);
+       udev_list_node_foreach(loop, &worker_list) {
+               struct worker *worker = node_to_worker(loop);
+               ssize_t count;
 
-       export_event_state(event, EVENT_QUEUED);
-       info(event->udev, "seq %llu queued, '%s' '%s'\n", udev_device_get_seqnum(event->dev),
-            udev_device_get_action(event->dev), udev_device_get_subsystem(event->dev));
+               if (worker->state != WORKER_IDLE)
+                       continue;
 
-       util_strlcpy(filename, udev_get_dev_path(event->udev), sizeof(filename));
-       util_strlcat(filename, "/.udev/uevent_seqnum", sizeof(filename));
-       fd = open(filename, O_WRONLY|O_TRUNC|O_CREAT, 0644);
-       if (fd >= 0) {
-               char str[32];
-               int len;
+               count = udev_monitor_send_device(monitor, worker->monitor, event->dev);
+               if (count < 0) {
+                       err(event->udev, "worker [%u] did not accept message %zi (%m), kill it\n", worker->pid, count);
+                       kill(worker->pid, SIGKILL);
+                       worker->state = WORKER_KILLED;
+                       continue;
+               }
+               worker_ref(worker);
+               worker->event = event;
+               worker->state = WORKER_RUNNING;
+               event->state = EVENT_RUNNING;
+               return;
+       }
 
-               len = sprintf(str, "%llu\n", udev_device_get_seqnum(event->dev));
-               write(fd, str, len);
-               close(fd);
+       if (childs >= max_childs) {
+               info(event->udev, "maximum number (%i) of childs reached\n", childs);
+               return;
        }
 
+       /* start new worker and pass initial device */
+       worker_new(event);
+}
+
+static void event_queue_insert(struct udev_device *dev)
+{
+       struct event *event;
+
+       event = calloc(1, sizeof(struct event));
+       if (event == NULL)
+               return;
+
+       event->udev = udev_device_get_udev(dev);
+       event->dev = dev;
+       event->seqnum = udev_device_get_seqnum(dev);
+       event->devpath = udev_device_get_devpath(dev);
+       event->devpath_len = strlen(event->devpath);
+       event->devpath_old = udev_device_get_devpath_old(dev);
+       event->devnum = udev_device_get_devnum(dev);
+       event->is_block = (strcmp("block", udev_device_get_subsystem(dev)) == 0);
+
+       udev_queue_export_device_queued(udev_queue_export, dev);
+       info(event->udev, "seq %llu queued, '%s' '%s'\n", udev_device_get_seqnum(dev),
+            udev_device_get_action(dev), udev_device_get_subsystem(dev));
 
+       event->state = EVENT_QUEUED;
        udev_list_node_append(&event->node, &event_list);
-       run_exec_q = 1;
 
        /* run all events with a timeout set immediately */
-       if (udev_device_get_timeout(event->dev) > 0) {
-               event_fork(event);
+       if (udev_device_get_timeout(dev) > 0) {
+               worker_new(event);
                return;
        }
 }
 
+static void worker_kill(struct udev *udev, int retain)
+{
+       struct udev_list_node *loop;
+       int max;
+
+       if (childs <= retain)
+               return;
+
+       max = childs - retain;
+
+       udev_list_node_foreach(loop, &worker_list) {
+               struct worker *worker = node_to_worker(loop);
+
+               if (max-- <= 0)
+                       break;
+
+               if (worker->state == WORKER_KILLED)
+                       continue;
+
+               worker->state = WORKER_KILLED;
+               kill(worker->pid, SIGTERM);
+       }
+}
+
 static int mem_size_mb(void)
 {
-       FILEf;
+       FILE *f;
        char buf[4096];
        long int memsize = -1;
 
@@ -306,132 +475,117 @@ static int mem_size_mb(void)
        return memsize;
 }
 
-static int compare_devpath(const char *running, const char *waiting)
-{
-       int i = 0;
-
-       while (running[i] != '\0' && running[i] == waiting[i])
-               i++;
-
-       /* identical device event found */
-       if (running[i] == '\0' && waiting[i] == '\0')
-               return 1;
-
-       /* parent device event found */
-       if (running[i] == '\0' && waiting[i] == '/')
-               return 2;
-
-       /* child device event found */
-       if (running[i] == '/' && waiting[i] == '\0')
-               return 3;
-
-       /* no matching event */
-       return 0;
-}
-
-/* lookup event for identical, parent, child, or physical device */
-static int devpath_busy(struct udev_event *event)
+/* lookup event for identical, parent, child device */
+static bool is_devpath_busy(struct event *event)
 {
        struct udev_list_node *loop;
+       size_t common;
 
-       if (event->delaying_seqnum > 0) {
-       }
        /* check if queue contains events we depend on */
        udev_list_node_foreach(loop, &event_list) {
-               struct udev_event *loop_event = node_to_event(loop);
+               struct event *loop_event = node_to_event(loop);
 
                /* we already found a later event, earlier can not block us, no need to check again */
-               if (udev_device_get_seqnum(loop_event->dev) < event->delaying_seqnum)
+               if (loop_event->seqnum < event->delaying_seqnum)
                        continue;
 
                /* event we checked earlier still exists, no need to check again */
-               if (udev_device_get_seqnum(loop_event->dev) == event->delaying_seqnum)
-                       return 2;
+               if (loop_event->seqnum == event->delaying_seqnum)
+                       return true;
 
                /* found ourself, no later event can block us */
-               if (udev_device_get_seqnum(loop_event->dev) >= udev_device_get_seqnum(event->dev))
+               if (loop_event->seqnum >= event->seqnum)
                        break;
 
+               /* check major/minor */
+               if (major(event->devnum) != 0 && event->devnum == loop_event->devnum && event->is_block == loop_event->is_block)
+                       return true;
+
                /* check our old name */
-               if (udev_device_get_devpath_old(event->dev) != NULL)
-                       if (strcmp(udev_device_get_devpath(loop_event->dev), udev_device_get_devpath_old(event->dev)) == 0) {
-                               event->delaying_seqnum = udev_device_get_seqnum(loop_event->dev);
-                               return 3;
-                       }
+               if (event->devpath_old != NULL && strcmp(loop_event->devpath, event->devpath_old) == 0) {
+                       event->delaying_seqnum = loop_event->seqnum;
+                       return true;
+               }
 
-               /* check identical, parent, or child device event */
-               if (compare_devpath(udev_device_get_devpath(loop_event->dev), udev_device_get_devpath(event->dev)) != 0) {
-                       dbg(event->udev, "%llu, device event still pending %llu (%s)\n",
-                           udev_device_get_seqnum(event->dev),
-                           udev_device_get_seqnum(loop_event->dev),
-                           udev_device_get_devpath(loop_event->dev));
-                       event->delaying_seqnum = udev_device_get_seqnum(loop_event->dev);
-                       return 4;
+               /* compare devpath */
+               common = MIN(loop_event->devpath_len, event->devpath_len);
+
+               /* one devpath is contained in the other? */
+               if (memcmp(loop_event->devpath, event->devpath, common) != 0)
+                       continue;
+
+               /* identical device event found */
+               if (loop_event->devpath_len == event->devpath_len) {
+                       event->delaying_seqnum = loop_event->seqnum;
+                       return true;
                }
 
-               /* check for our major:minor number */
-               if (major(udev_device_get_devnum(event->dev)) > 0 &&
-                   udev_device_get_devnum(loop_event->dev) == udev_device_get_devnum(event->dev) &&
-                   strcmp(udev_device_get_subsystem(event->dev), udev_device_get_subsystem(loop_event->dev)) == 0) {
-                       dbg(event->udev, "%llu, device event still pending %llu (%d:%d)\n",
-                           udev_device_get_seqnum(event->dev),
-                           udev_device_get_seqnum(loop_event->dev),
-                           major(udev_device_get_devnum(loop_event->dev)), minor(udev_device_get_devnum(loop_event->dev)));
-                       event->delaying_seqnum = udev_device_get_seqnum(loop_event->dev);
-                       return 5;
+               /* parent device event found */
+               if (event->devpath[common] == '/') {
+                       event->delaying_seqnum = loop_event->seqnum;
+                       return true;
                }
 
-               /* check physical device event (special case of parent) */
-               if (udev_device_get_physdevpath(event->dev) != NULL &&
-                   strcmp(udev_device_get_action(event->dev), "add") == 0)
-                       if (compare_devpath(udev_device_get_devpath(loop_event->dev),
-                                           udev_device_get_physdevpath(event->dev)) != 0) {
-                               dbg(event->udev, "%llu, physical device event still pending %llu (%s)\n",
-                                   udev_device_get_seqnum(event->dev),
-                                   udev_device_get_seqnum(loop_event->dev),
-                                   udev_device_get_devpath(loop_event->dev));
-                               event->delaying_seqnum = udev_device_get_seqnum(loop_event->dev);
-                               return 6;
-                       }
+               /* child device event found */
+               if (loop_event->devpath[common] == '/') {
+                       event->delaying_seqnum = loop_event->seqnum;
+                       return true;
+               }
+
+               /* no matching device */
+               continue;
        }
-       return 0;
+
+       return false;
 }
 
-/* serializes events for the identical and parent and child devices */
-static void event_queue_manager(struct udev *udev)
+static void events_start(struct udev *udev)
 {
        struct udev_list_node *loop;
-       struct udev_list_node *tmp;
 
-       if (udev_list_is_empty(&event_list)) {
-               if (childs > 0) {
-                       err(udev, "event list empty, but childs count is %i", childs);
-                       childs = 0;
+       udev_list_node_foreach(loop, &event_list) {
+               struct event *event = node_to_event(loop);
+
+               if (event->state != EVENT_QUEUED)
+                       continue;
+
+               /* do not start event if parent or child event is still running */
+               if (is_devpath_busy(event)) {
+                       dbg(udev, "delay seq %llu (%s)\n", event->seqnum, event->devpath);
+                       continue;
                }
-               return;
+
+               event_run(event);
        }
+}
 
-       udev_list_node_foreach_safe(loop, tmp, &event_list) {
-               struct udev_event *loop_event = node_to_event(loop);
+static void worker_returned(void)
+{
+       while (1) {
+               struct worker_message msg;
+               ssize_t size;
+               struct udev_list_node *loop;
 
-               if (childs >= max_childs) {
-                       info(udev, "maximum number (%i) of childs reached\n", childs);
+               size = recv(pfd[FD_WORKER].fd, &msg, sizeof(struct worker_message), MSG_DONTWAIT);
+               if (size != sizeof(struct worker_message))
                        break;
-               }
 
-               if (loop_event->pid != 0)
-                       continue;
+               /* lookup worker who sent the signal */
+               udev_list_node_foreach(loop, &worker_list) {
+                       struct worker *worker = node_to_worker(loop);
 
-               /* do not start event if parent or child event is still running */
-               if (devpath_busy(loop_event) != 0) {
-                       dbg(udev, "delay seq %llu (%s)\n",
-                           udev_device_get_seqnum(loop_event->dev),
-                           udev_device_get_devpath(loop_event->dev));
-                       continue;
-               }
+                       if (worker->pid != msg.pid)
+                               continue;
 
-               event_fork(loop_event);
-               dbg(udev, "moved seq %llu to running list\n", udev_device_get_seqnum(loop_event->dev));
+                       /* worker returned */
+                       worker->event->exitcode = msg.exitcode;
+                       event_queue_delete(worker->event);
+                       worker->event = NULL;
+                       if (worker->state != WORKER_KILLED)
+                               worker->state = WORKER_IDLE;
+                       worker_unref(worker);
+                       break;
+               }
        }
 }
 
@@ -451,22 +605,22 @@ static void handle_ctrl_msg(struct udev_ctrl *uctrl)
        if (i >= 0) {
                info(udev, "udevd message (SET_LOG_PRIORITY) received, log_priority=%i\n", i);
                udev_set_log_priority(udev, i);
+               worker_kill(udev, 0);
        }
 
        if (udev_ctrl_get_stop_exec_queue(ctrl_msg) > 0) {
                info(udev, "udevd message (STOP_EXEC_QUEUE) received\n");
-               stop_exec_q = 1;
+               stop_exec_queue = true;
        }
 
        if (udev_ctrl_get_start_exec_queue(ctrl_msg) > 0) {
                info(udev, "udevd message (START_EXEC_QUEUE) received\n");
-               stop_exec_q = 0;
-               event_queue_manager(udev);
+               stop_exec_queue = false;
        }
 
        if (udev_ctrl_get_reload_rules(ctrl_msg) > 0) {
                info(udev, "udevd message (RELOAD_RULES) received\n");
-               reload_config = 1;
+               reload_config = true;
        }
 
        str = udev_ctrl_get_set_env(ctrl_msg);
@@ -493,6 +647,7 @@ static void handle_ctrl_msg(struct udev_ctrl *uctrl)
                        }
                        free(key);
                }
+               worker_kill(udev, 0);
        }
 
        i = udev_ctrl_get_set_max_childs(ctrl_msg);
@@ -500,128 +655,166 @@ static void handle_ctrl_msg(struct udev_ctrl *uctrl)
                info(udev, "udevd message (SET_MAX_CHILDS) received, max_childs=%i\n", i);
                max_childs = i;
        }
+
+       settle_pid = udev_ctrl_get_settle(ctrl_msg);
+       if (settle_pid > 0) {
+               info(udev, "udevd message (SETTLE) received\n");
+               kill(settle_pid, SIGUSR1);
+               settle_pid = 0;
+       }
        udev_ctrl_msg_unref(ctrl_msg);
 }
 
-static void asmlinkage sig_handler(int signum)
+/* read inotify messages */
+static int handle_inotify(struct udev *udev)
 {
-       switch (signum) {
-               case SIGINT:
-               case SIGTERM:
-                       udev_exit = 1;
-                       break;
-               case SIGCHLD:
-                       /* set flag, then write to pipe if needed */
-                       sigchilds_waiting = 1;
-                       break;
-               case SIGHUP:
-                       reload_config = 1;
-                       break;
+       int nbytes, pos;
+       char *buf;
+       struct inotify_event *ev;
+
+       if ((ioctl(pfd[FD_INOTIFY].fd, FIONREAD, &nbytes) < 0) || (nbytes <= 0))
+               return 0;
+
+       buf = malloc(nbytes);
+       if (buf == NULL) {
+               err(udev, "error getting buffer for inotify\n");
+               return -1;
        }
 
-       /* write to pipe, which will wakeup select() in our mainloop */
-       write(signal_pipe[WRITE_END], "", 1);
-}
+       nbytes = read(pfd[FD_INOTIFY].fd, buf, nbytes);
 
-static void udev_done(int pid, int exitstatus)
-{
-       struct udev_list_node *loop;
+       for (pos = 0; pos < nbytes; pos += sizeof(struct inotify_event) + ev->len) {
+               struct udev_device *dev;
 
-       /* find event associated with pid and delete it */
-       udev_list_node_foreach(loop, &event_list) {
-               struct udev_event *loop_event = node_to_event(loop);
-
-               if (loop_event->pid == pid) {
-                       info(loop_event->udev, "seq %llu cleanup, pid [%d], status %i, %ld seconds old\n",
-                            udev_device_get_seqnum(loop_event->dev), loop_event->pid,
-                            exitstatus, time(NULL) - loop_event->queue_time);
-                       loop_event->exitstatus = exitstatus;
-                       if (debug_trace)
-                               fprintf(stderr, "exit %s (%llu)\n",
-                                      udev_device_get_syspath(loop_event->dev),
-                                      udev_device_get_seqnum(loop_event->dev));
-                       event_queue_delete(loop_event);
-                       childs--;
-
-                       /* there may be dependent events waiting */
-                       run_exec_q = 1;
-                       return;
+               ev = (struct inotify_event *)(buf + pos);
+               if (ev->len) {
+                       dbg(udev, "inotify event: %x for %s\n", ev->mask, ev->name);
+                       reload_config = true;
+                       continue;
                }
+
+               dev = udev_watch_lookup(udev, ev->wd);
+               if (dev != NULL) {
+                       dbg(udev, "inotify event: %x for %s\n", ev->mask, udev_device_get_devnode(dev));
+                       if (ev->mask & IN_CLOSE_WRITE) {
+                               char filename[UTIL_PATH_SIZE];
+                               int fd;
+
+                               info(udev, "device %s closed, synthesising 'change'\n", udev_device_get_devnode(dev));
+                               util_strscpyl(filename, sizeof(filename), udev_device_get_syspath(dev), "/uevent", NULL);
+                               fd = open(filename, O_WRONLY);
+                               if (fd < 0 || write(fd, "change", 6) < 0)
+                                       info(udev, "error writing uevent: %m\n");
+                               close(fd);
+                       }
+                       if (ev->mask & IN_IGNORED)
+                               udev_watch_end(udev, dev);
+
+                       udev_device_unref(dev);
+               }
+
        }
+
+       free(buf);
+       return 0;
 }
 
-static void reap_sigchilds(void)
+static void handle_signal(struct udev *udev, int signo)
 {
-       pid_t pid;
-       int status;
-
-       while (1) {
-               pid = waitpid(-1, &status, WNOHANG);
-               if (pid <= 0)
-                       break;
-               if (WIFEXITED(status))
-                       status = WEXITSTATUS(status);
-               else if (WIFSIGNALED(status))
-                       status = WTERMSIG(status) + 128;
-               else
-                       status = 0;
-               udev_done(pid, status);
+       switch (signo) {
+       case SIGINT:
+       case SIGTERM:
+               udev_exit = true;
+               break;
+       case SIGCHLD:
+               while (1) {
+                       pid_t pid;
+                       int status;
+                       struct udev_list_node *loop, *tmp;
+
+                       pid = waitpid(-1, &status, WNOHANG);
+                       if (pid <= 0)
+                               break;
+
+                       udev_list_node_foreach_safe(loop, tmp, &worker_list) {
+                               struct worker *worker = node_to_worker(loop);
+
+                               if (worker->pid != pid)
+                                       continue;
+
+                               info(udev, "worker [%u] exit\n", pid);
+                               if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
+                                       err(udev, "worker [%u] unexpectedly returned with status 0x%04x\n", pid, status);
+                                       if (worker->event != NULL) {
+                                               err(udev, "worker [%u] failed while handling '%s'\n", pid, worker->event->devpath);
+                                               worker->event->exitcode = -32;
+                                               event_queue_delete(worker->event);
+                                               /* drop reference from running event */
+                                               worker_unref(worker);
+                                       }
+                               }
+                               worker_unref(worker);
+                               break;
+                       }
+               }
+               break;
+       case SIGHUP:
+               reload_config = true;
+               break;
        }
 }
 
-static void export_initial_seqnum(struct udev *udev)
+static void startup_log(struct udev *udev)
 {
-       char filename[UTIL_PATH_SIZE];
-       int fd;
-       char seqnum[32];
-       ssize_t len = 0;
-
-       util_strlcpy(filename, udev_get_sys_path(udev), sizeof(filename));
-       util_strlcat(filename, "/kernel/uevent_seqnum", sizeof(filename));
-       fd = open(filename, O_RDONLY);
-       if (fd >= 0) {
-               len = read(fd, seqnum, sizeof(seqnum)-1);
-               close(fd);
-       }
-       if (len <= 0) {
-               strcpy(seqnum, "0\n");
-               len = 3;
-       }
-       util_strlcpy(filename, udev_get_dev_path(udev), sizeof(filename));
-       util_strlcat(filename, "/.udev/uevent_seqnum", sizeof(filename));
-       util_create_path(udev, filename);
-       fd = open(filename, O_WRONLY|O_TRUNC|O_CREAT, 0644);
-       if (fd >= 0) {
-               write(fd, seqnum, len);
-               close(fd);
+       FILE *f;
+       char path[UTIL_PATH_SIZE];
+       struct stat statbuf;
+
+       f = fopen("/dev/kmsg", "w");
+       if (f != NULL)
+               fprintf(f, "<6>udev: starting version " VERSION "\n");
+
+       util_strscpyl(path, sizeof(path), udev_get_sys_path(udev), "/class/mem/null", NULL);
+       if (lstat(path, &statbuf) == 0 && S_ISDIR(statbuf.st_mode)) {
+               const char *depr_str =
+                       "udev: missing sysfs features; please update the kernel "
+                       "or disable the kernel's CONFIG_SYSFS_DEPRECATED option; "
+                       "udev may fail to work correctly";
+
+               if (f != NULL)
+                       fprintf(f, "<3>%s\n", depr_str);
+               err(udev, "%s\n", depr_str);
+               sleep(15);
        }
+
+       if (f != NULL)
+               fclose(f);
 }
 
 int main(int argc, char *argv[])
 {
        struct udev *udev;
-       int err;
        int fd;
-       struct sigaction act;
-       fd_set readfds;
+       sigset_t mask;
        const char *value;
-       int daemonize = 0;
+       int daemonize = false;
+       int resolve_names = 1;
        static const struct option options[] = {
                { "daemon", no_argument, NULL, 'd' },
                { "debug-trace", no_argument, NULL, 't' },
                { "debug", no_argument, NULL, 'D' },
                { "help", no_argument, NULL, 'h' },
                { "version", no_argument, NULL, 'V' },
+               { "resolve-names", required_argument, NULL, 'N' },
                {}
        };
        int rc = 1;
-       int maxfd;
 
        udev = udev_new();
        if (udev == NULL)
                goto exit;
 
-       logging_init("udevd");
+       udev_log_init("udevd");
        udev_set_log_fn(udev, log_fn);
        info(udev, "version %s\n", VERSION);
        udev_selinux_init(udev);
@@ -635,18 +828,32 @@ int main(int argc, char *argv[])
 
                switch (option) {
                case 'd':
-                       daemonize = 1;
+                       daemonize = true;
                        break;
                case 't':
-                       debug_trace = 1;
+                       debug_trace = true;
                        break;
                case 'D':
-                       debug = 1;
+                       debug = true;
                        if (udev_get_log_priority(udev) < LOG_INFO)
                                udev_set_log_priority(udev, LOG_INFO);
                        break;
+               case 'N':
+                       if (strcmp (optarg, "early") == 0) {
+                               resolve_names = 1;
+                       } else if (strcmp (optarg, "late") == 0) {
+                               resolve_names = 0;
+                       } else if (strcmp (optarg, "never") == 0) {
+                               resolve_names = -1;
+                       } else {
+                               fprintf(stderr, "resolve-names must be early, late or never\n");
+                               err(udev, "resolve-names must be early, late or never\n");
+                               goto exit;
+                       }
+                       break;
                case 'h':
-                       printf("Usage: udevd [--help] [--daemon] [--debug-trace] [--debug] [--version]\n");
+                       printf("Usage: udevd [--help] [--daemon] [--debug-trace] [--debug] "
+                              "[--resolve-names=early|late|never] [--version]\n");
                        goto exit;
                case 'V':
                        printf("%s\n", VERSION);
@@ -681,58 +888,81 @@ int main(int argc, char *argv[])
                rc = 1;
                goto exit;
        }
-
        if (udev_ctrl_enable_receiving(udev_ctrl) < 0) {
                fprintf(stderr, "error binding control socket, seems udevd is already running\n");
                err(udev, "error binding control socket, seems udevd is already running\n");
                rc = 1;
                goto exit;
        }
+       pfd[FD_CONTROL].fd = udev_ctrl_get_fd(udev_ctrl);
 
-       kernel_monitor = udev_monitor_new_from_netlink(udev);
-       if (kernel_monitor == NULL || udev_monitor_enable_receiving(kernel_monitor) < 0) {
+       monitor = udev_monitor_new_from_netlink(udev, "kernel");
+       if (monitor == NULL || udev_monitor_enable_receiving(monitor) < 0) {
                fprintf(stderr, "error initializing netlink socket\n");
                err(udev, "error initializing netlink socket\n");
                rc = 3;
                goto exit;
        }
-       udev_monitor_set_receive_buffer_size(kernel_monitor, 128*1024*1024);
-
-       err = pipe(signal_pipe);
-       if (err < 0) {
-               err(udev, "error getting pipes: %m\n");
+       udev_monitor_set_receive_buffer_size(monitor, 128*1024*1024);
+       pfd[FD_NETLINK].fd = udev_monitor_get_fd(monitor);
+
+       pfd[FD_INOTIFY].fd = udev_watch_init(udev);
+       if (pfd[FD_INOTIFY].fd < 0) {
+               fprintf(stderr, "error initializing inotify\n");
+               err(udev, "error initializing inotify\n");
+               rc = 4;
                goto exit;
        }
 
-       err = fcntl(signal_pipe[READ_END], F_GETFL, 0);
-       if (err < 0) {
-               err(udev, "error fcntl on read pipe: %m\n");
-               goto exit;
+       if (udev_get_rules_path(udev) != NULL) {
+               inotify_add_watch(pfd[FD_INOTIFY].fd, udev_get_rules_path(udev),
+                                 IN_CREATE | IN_DELETE | IN_MOVE | IN_CLOSE_WRITE);
+       } else {
+               char filename[UTIL_PATH_SIZE];
+
+               inotify_add_watch(pfd[FD_INOTIFY].fd, LIBEXECDIR "/rules.d",
+                                 IN_CREATE | IN_DELETE | IN_MOVE | IN_CLOSE_WRITE);
+               inotify_add_watch(pfd[FD_INOTIFY].fd, SYSCONFDIR "/udev/rules.d",
+                                 IN_CREATE | IN_DELETE | IN_MOVE | IN_CLOSE_WRITE);
+
+               /* watch dynamic rules directory */
+               util_strscpyl(filename, sizeof(filename), udev_get_dev_path(udev), "/.udev/rules.d", NULL);
+               inotify_add_watch(pfd[FD_INOTIFY].fd, filename,
+                                 IN_CREATE | IN_DELETE | IN_MOVE | IN_CLOSE_WRITE);
        }
-       err = fcntl(signal_pipe[READ_END], F_SETFL, err | O_NONBLOCK);
-       if (err < 0) {
-               err(udev, "error fcntl on read pipe: %m\n");
+       udev_watch_restore(udev);
+
+       /* block and listen to all signals on signalfd */
+       sigfillset(&mask);
+       sigprocmask(SIG_SETMASK, &mask, &orig_sigmask);
+       pfd[FD_SIGNAL].fd = signalfd(-1, &mask, 0);
+       if (pfd[FD_SIGNAL].fd < 0) {
+               fprintf(stderr, "error getting signalfd\n");
+               err(udev, "error getting signalfd\n");
+               rc = 5;
                goto exit;
        }
 
-       err = fcntl(signal_pipe[WRITE_END], F_GETFL, 0);
-       if (err < 0) {
-               err(udev, "error fcntl on write pipe: %m\n");
-               goto exit;
-       }
-       err = fcntl(signal_pipe[WRITE_END], F_SETFL, err | O_NONBLOCK);
-       if (err < 0) {
-               err(udev, "error fcntl on write pipe: %m\n");
+       /* unnamed socket from workers to the main daemon */
+       if (socketpair(AF_LOCAL, SOCK_DGRAM|SOCK_CLOEXEC, 0, worker_watch) < 0) {
+               fprintf(stderr, "error getting socketpair\n");
+               err(udev, "error getting socketpair\n");
+               rc = 6;
                goto exit;
        }
+       pfd[FD_WORKER].fd = worker_watch[READ_END];
 
-       rules = udev_rules_new(udev, 1);
+       rules = udev_rules_new(udev, resolve_names);
        if (rules == NULL) {
                err(udev, "error reading rules\n");
                goto exit;
        }
-       udev_list_init(&event_list);
-       export_initial_seqnum(udev);
+
+       udev_queue_export = udev_queue_export_new(udev);
+       if (udev_queue_export == NULL) {
+               err(udev, "error creating queue file\n");
+               goto exit;
+       }
 
        if (daemonize) {
                pid_t pid;
@@ -740,19 +970,19 @@ int main(int argc, char *argv[])
                pid = fork();
                switch (pid) {
                case 0:
-                       dbg(udev, "daemonized fork running\n");
                        break;
                case -1:
                        err(udev, "fork of daemon failed: %m\n");
                        rc = 4;
                        goto exit;
                default:
-                       dbg(udev, "child [%u] running, parent exits\n", pid);
                        rc = 0;
                        goto exit;
                }
        }
 
+       startup_log(udev);
+
        /* redirect std{out,err} */
        if (!debug && !debug_trace) {
                dup2(fd, STDIN_FILENO);
@@ -771,192 +1001,124 @@ int main(int argc, char *argv[])
 
        /* OOM_DISABLE == -17 */
        fd = open("/proc/self/oom_adj", O_RDWR);
-       if (fd < 0)
+       if (fd < 0) {
                err(udev, "error disabling OOM: %m\n");
-       else {
+       else {
                write(fd, "-17", 3);
                close(fd);
        }
 
-       fd = open("/dev/kmsg", O_WRONLY);
-       if (fd > 0) {
-               const char *ver_str = "<6>udev: starting version " VERSION "\n";
-               char path[UTIL_PATH_SIZE];
-               struct stat statbuf;
-
-               write(fd, ver_str, strlen(ver_str));
-               util_strlcpy(path, udev_get_sys_path(udev), sizeof(path));
-               util_strlcat(path, "/class/mem/null", sizeof(path));
-               if (lstat(path, &statbuf) == 0) {
-                       if (S_ISDIR(statbuf.st_mode)) {
-                               const char *depr_str = "<6>udev: deprecated sysfs layout (kernel too old, "
-                                                       "or CONFIG_SYSFS_DEPRECATED) is unsupported, some "
-                                                       "udev features may fail\n";
-
-                               write(fd, depr_str, strlen(depr_str));
-                       }
-               }
-               close(fd);
-       }
-
-       /* set signal handlers */
-       memset(&act, 0x00, sizeof(struct sigaction));
-       act.sa_handler = (void (*)(int)) sig_handler;
-       sigemptyset(&act.sa_mask);
-       act.sa_flags = SA_RESTART;
-       sigaction(SIGINT, &act, NULL);
-       sigaction(SIGTERM, &act, NULL);
-       sigaction(SIGCHLD, &act, NULL);
-       sigaction(SIGHUP, &act, NULL);
-
-       /* watch rules directory */
-       inotify_fd = inotify_init();
-       if (inotify_fd >= 0) {
-               if (udev_get_rules_path(udev) != NULL) {
-                       inotify_add_watch(inotify_fd, udev_get_rules_path(udev),
-                                         IN_CREATE | IN_DELETE | IN_MOVE | IN_CLOSE_WRITE);
-               } else {
-                       char filename[UTIL_PATH_SIZE];
-
-                       inotify_add_watch(inotify_fd, UDEV_PREFIX "/lib/udev/rules.d",
-                                         IN_CREATE | IN_DELETE | IN_MOVE | IN_CLOSE_WRITE);
-                       inotify_add_watch(inotify_fd, SYSCONFDIR "/udev/rules.d",
-                                         IN_CREATE | IN_DELETE | IN_MOVE | IN_CLOSE_WRITE);
-
-                       /* watch dynamic rules directory */
-                       util_strlcpy(filename, udev_get_dev_path(udev), sizeof(filename));
-                       util_strlcat(filename, "/.udev/rules.d", sizeof(filename));
-                       inotify_add_watch(inotify_fd, filename,
-                                         IN_CREATE | IN_DELETE | IN_MOVE | IN_CLOSE_WRITE);
-               }
-       } else if (errno == ENOSYS)
-               err(udev, "the kernel does not support inotify, udevd can't monitor rules file changes\n");
-       else
-               err(udev, "inotify_init failed: %m\n");
-
        /* in trace mode run one event after the other */
        if (debug_trace) {
                max_childs = 1;
        } else {
                int memsize = mem_size_mb();
+
                if (memsize > 0)
-                       max_childs = 128 + (memsize / 4);
+                       max_childs = 128 + (memsize / 8);
                else
-                       max_childs = UDEVD_MAX_CHILDS;
+                       max_childs = 128;
        }
+
        /* possibly overwrite maximum limit of executed events */
        value = getenv("UDEVD_MAX_CHILDS");
        if (value)
                max_childs = strtoul(value, NULL, 10);
        info(udev, "initialize max_childs to %u\n", max_childs);
 
-       maxfd = udev_ctrl_get_fd(udev_ctrl);
-       maxfd = UDEV_MAX(maxfd, udev_monitor_get_fd(kernel_monitor));
-       maxfd = UDEV_MAX(maxfd, signal_pipe[READ_END]);
-       maxfd = UDEV_MAX(maxfd, inotify_fd);
+       udev_list_init(&event_list);
+       udev_list_init(&worker_list);
+
        while (!udev_exit) {
                int fdcount;
+               int timeout;
 
-               FD_ZERO(&readfds);
-               FD_SET(signal_pipe[READ_END], &readfds);
-               FD_SET(udev_ctrl_get_fd(udev_ctrl), &readfds);
-               FD_SET(udev_monitor_get_fd(kernel_monitor), &readfds);
-               if (inotify_fd >= 0)
-                       FD_SET(inotify_fd, &readfds);
-               fdcount = select(maxfd+1, &readfds, NULL, NULL, NULL);
-               if (fdcount < 0) {
-                       if (errno != EINTR)
-                               err(udev, "error in select: %m\n");
+               /* set timeout to kill idle workers */
+               if (udev_list_is_empty(&event_list) && childs > 2)
+                       timeout = 3 * 1000;
+               else
+                       timeout = -1;
+               /* wait for events */
+               fdcount = poll(pfd, ARRAY_SIZE(pfd), timeout);
+               if (fdcount < 0)
                        continue;
-               }
 
-               /* get control message */
-               if (FD_ISSET(udev_ctrl_get_fd(udev_ctrl), &readfds))
-                       handle_ctrl_msg(udev_ctrl);
+               /* timeout - kill idle workers */
+               if (fdcount == 0)
+                       worker_kill(udev, 2);
+
+               /* event has finished */
+               if (pfd[FD_WORKER].revents & POLLIN)
+                       worker_returned();
 
                /* get kernel uevent */
-               if (FD_ISSET(udev_monitor_get_fd(kernel_monitor), &readfds)) {
+               if (pfd[FD_NETLINK].revents & POLLIN) {
                        struct udev_device *dev;
 
-                       dev = udev_monitor_receive_device(kernel_monitor);
-                       if (dev != NULL) {
-                               struct udev_event *event;
-
-                               event = udev_event_new(dev);
-                               if (event != NULL)
-                                       event_queue_insert(event);
-                               else
-                                       udev_device_unref(dev);
-                       }
+                       dev = udev_monitor_receive_device(monitor);
+                       if (dev != NULL)
+                               event_queue_insert(dev);
+                       else
+                               udev_device_unref(dev);
                }
 
-               /* received a signal, clear our notification pipe */
-               if (FD_ISSET(signal_pipe[READ_END], &readfds)) {
-                       char buf[256];
-
-                       read(signal_pipe[READ_END], &buf, sizeof(buf));
-               }
+               /* start new events */
+               if (!udev_list_is_empty(&event_list) && !stop_exec_queue)
+                       events_start(udev);
 
-               /* rules directory inotify watch */
-               if ((inotify_fd >= 0) && FD_ISSET(inotify_fd, &readfds)) {
-                       int nbytes;
+               /* get signal */
+               if (pfd[FD_SIGNAL].revents & POLLIN) {
+                       struct signalfd_siginfo fdsi;
+                       ssize_t size;
 
-                       /* discard all possible events, we can just reload the config */
-                       if ((ioctl(inotify_fd, FIONREAD, &nbytes) == 0) && nbytes > 0) {
-                               char *buf;
-
-                               reload_config = 1;
-                               buf = malloc(nbytes);
-                               if (buf == NULL) {
-                                       err(udev, "error getting buffer for inotify, disable watching\n");
-                                       close(inotify_fd);
-                                       inotify_fd = -1;
-                               }
-                               read(inotify_fd, buf, nbytes);
-                               free(buf);
-                       }
+                       size = read(pfd[FD_SIGNAL].fd, &fdsi, sizeof(struct signalfd_siginfo));
+                       if (size == sizeof(struct signalfd_siginfo))
+                               handle_signal(udev, fdsi.ssi_signo);
                }
 
+               /* device node and rules directory inotify watch */
+               if (pfd[FD_INOTIFY].revents & POLLIN)
+                       handle_inotify(udev);
+
+               /*
+                * get control message
+                *
+                * This needs to be after the inotify handling, to make sure,
+                * that the settle signal is send back after the possibly generated
+                * "change" events by the inotify device node watch.
+                */
+               if (pfd[FD_CONTROL].revents & POLLIN)
+                       handle_ctrl_msg(udev_ctrl);
+
                /* rules changed, set by inotify or a HUP signal */
                if (reload_config) {
                        struct udev_rules *rules_new;
 
-                       reload_config = 0;
-                       rules_new = udev_rules_new(udev, 1);
+                       worker_kill(udev, 0);
+                       rules_new = udev_rules_new(udev, resolve_names);
                        if (rules_new != NULL) {
                                udev_rules_unref(rules);
                                rules = rules_new;
                        }
-               }
-
-               if (sigchilds_waiting) {
-                       sigchilds_waiting = 0;
-                       reap_sigchilds();
-               }
-
-               if (run_exec_q) {
-                       run_exec_q = 0;
-                       if (!stop_exec_q)
-                               event_queue_manager(udev);
+                       reload_config = 0;
                }
        }
-       rc = 0;
 
+       udev_queue_export_cleanup(udev_queue_export);
+       rc = 0;
 exit:
+       udev_queue_export_unref(udev_queue_export);
        udev_rules_unref(rules);
-
-       if (signal_pipe[READ_END] >= 0)
-               close(signal_pipe[READ_END]);
-       if (signal_pipe[WRITE_END] >= 0)
-               close(signal_pipe[WRITE_END]);
-
        udev_ctrl_unref(udev_ctrl);
-       if (inotify_fd >= 0)
-               close(inotify_fd);
-       udev_monitor_unref(kernel_monitor);
-
+       if (pfd[FD_SIGNAL].fd >= 0)
+               close(pfd[FD_SIGNAL].fd);
+       if (worker_watch[READ_END] >= 0)
+               close(worker_watch[READ_END]);
+       if (worker_watch[WRITE_END] >= 0)
+               close(worker_watch[WRITE_END]);
+       udev_monitor_unref(monitor);
        udev_selinux_exit(udev);
        udev_unref(udev);
-       logging_close();
+       udev_log_close();
        return rc;
 }