udev: remove seqnum API and all assumptions about seqnums

The way the kernel namespaces have been implemented breaks assumptions
udev made regarding uevent sequence numbers. Creating devices in a
namespace "steals" uevents and its sequence numbers from the host. It
confuses the "udevadmin settle" logic, which might block until util a
timeout is reached, even when no uevent is pending.

Remove any assumptions about sequence numbers and deprecate libudev's
API exposing these numbers; none of that can reliably be used anymore
when namespaces are involved.

1 files changed, 22 insertions, 109 deletions

diff --git a/src/udev/udevadm-settle.c b/src/udev/udevadm-settle.c
index 927ea2a7f..65fc35f9a 100644
--- a/src/udev/udevadm-settle.c
+++ b/src/udev/udevadm-settle.c
@@ -41,42 +41,28 @@
 static void help(void) {
         printf("Usage: udevadm settle OPTIONS\n"
                "  -t,--timeout=<seconds>     maximum time to wait for events\n"
-               "  -s,--seq-start=<seqnum>    first seqnum to wait for\n"
-               "  -e,--seq-end=<seqnum>      last seqnum to wait for\n"
                "  -E,--exit-if-exists=<file> stop waiting if file exists\n"
-               "  -q,--quiet                 do not print list after timeout\n"
                "  -h,--help\n\n");
 }
 
 static int adm_settle(struct udev *udev, int argc, char *argv[])
 {
         static const struct option options[] = {
-                { "seq-start",      required_argument, NULL, 's' },
-                { "seq-end",        required_argument, NULL, 'e' },
+                { "seq-start",      required_argument, NULL, '\0' }, /* removed */
+                { "seq-end",        required_argument, NULL, '\0' }, /* removed */
                 { "timeout",        required_argument, NULL, 't' },
                 { "exit-if-exists", required_argument, NULL, 'E' },
-                { "quiet",          no_argument,       NULL, 'q' },
+                { "quiet",          no_argument,       NULL, 'q' },  /* removed */
                 { "help",           no_argument,       NULL, 'h' },
                 {}
         };
-        usec_t start_usec = now(CLOCK_MONOTONIC);
-        usec_t start = 0;
-        usec_t end = 0;
-        int quiet = 0;
         const char *exists = NULL;
         unsigned int timeout = 120;
         struct pollfd pfd[1] = { {.fd = -1}, };
-        _cleanup_udev_queue_unref_ struct udev_queue *udev_queue = NULL;
         int rc = EXIT_FAILURE, c;
 
-        while ((c = getopt_long(argc, argv, "s:e:t:E:qh", options, NULL)) >= 0)
+        while ((c = getopt_long(argc, argv, "s:e:t:E:qh", options, NULL)) >= 0) {
                 switch (c) {
-                case 's':
-                        start = strtoull(optarg, NULL, 0);
-                        break;
-                case 'e':
-                        end = strtoull(optarg, NULL, 0);
-                        break;
                 case 't': {
                         int r;
 
@@ -91,9 +77,6 @@ static int adm_settle(struct udev *udev, int argc, char *argv[])
                 case 'E':
                         exists = optarg;
                         break;
-                case 'q':
-                        quiet = 1;
-                        break;
                 case 'h':
                         help();
                         exit(EXIT_SUCCESS);
@@ -102,44 +85,13 @@ static int adm_settle(struct udev *udev, int argc, char *argv[])
                 default:
                         assert_not_reached("Unknown argument");
                 }
+        }
 
         if (optind < argc) {
                 fprintf(stderr, "Extraneous argument: '%s'\n", argv[optind]);
                 exit(EXIT_FAILURE);
         }
 
-        udev_queue = udev_queue_new(udev);
-        if (udev_queue == NULL)
-                exit(2);
-
-        if (start > 0) {
-                unsigned long long kernel_seq;
-
-                kernel_seq = udev_queue_get_kernel_seqnum(udev_queue);
-
-                /* unless specified, the last event is the current kernel seqnum */
-                if (end == 0)
-                        end = udev_queue_get_kernel_seqnum(udev_queue);
-
-                if (start > end) {
-                        log_error("seq-start larger than seq-end, ignoring");
-                        start = 0;
-                        end = 0;
-                }
-
-                if (start > kernel_seq || end > kernel_seq) {
-                        log_error("seq-start or seq-end larger than current kernel value, ignoring");
-                        start = 0;
-                        end = 0;
-                }
-                log_debug("start=%llu end=%llu current=%llu", (unsigned long long)start, (unsigned long long)end, kernel_seq);
-        } else {
-                if (end > 0) {
-                        log_error("seq-end needs seq-start parameter, ignoring");
-                        end = 0;
-                }
-        }
-
         /* guarantee that the udev daemon isn't pre-processing */
         if (getuid() == 0) {
                 struct udev_ctrl *uctrl;
@@ -160,73 +112,34 @@ static int adm_settle(struct udev *udev, int argc, char *argv[])
         pfd[0].fd = inotify_init1(IN_CLOEXEC);
         if (pfd[0].fd < 0) {
                 log_error("inotify_init failed: %m");
-        } else {
-                if (inotify_add_watch(pfd[0].fd, "/run/udev" , IN_MOVED_TO) < 0) {
-                        log_error("watching /run/udev failed");
-                        close(pfd[0].fd);
-                        pfd[0].fd = -1;
-                }
+                goto out;
         }
 
-        for (;;) {
-                struct stat statbuf;
+        if (inotify_add_watch(pfd[0].fd, "/run/udev/queue" , IN_DELETE) < 0) {
+                log_debug("watching /run/udev failed");
+                goto out;
+        }
 
-                if (exists != NULL && stat(exists, &statbuf) == 0) {
+        for (;;) {
+                if (exists && access(exists, F_OK) >= 0) {
                         rc = EXIT_SUCCESS;
                         break;
                 }
 
-                if (start > 0) {
-                        /* if asked for, wait for a specific sequence of events */
-                        if (udev_queue_get_seqnum_sequence_is_finished(udev_queue, start, end) == 1) {
-                                rc = EXIT_SUCCESS;
-                                break;
-                        }
-                } else {
-                        /* exit if queue is empty */
-                        if (udev_queue_get_queue_is_empty(udev_queue)) {
-                                rc = EXIT_SUCCESS;
-                                break;
-                        }
-                }
-
-                if (pfd[0].fd >= 0) {
-                        int delay;
-
-                        if (exists != NULL || start > 0)
-                                delay = 100;
-                        else
-                                delay = 1000;
-                        /* wake up after delay, or immediately after the queue is rebuilt */
-                        if (poll(pfd, 1, delay) > 0 && pfd[0].revents & POLLIN) {
-                                char buf[sizeof(struct inotify_event) + PATH_MAX];
-
-                                read(pfd[0].fd, buf, sizeof(buf));
-                        }
-                } else {
-                        sleep(1);
+                /* exit if queue is empty */
+                if (access("/run/udev/queue", F_OK) < 0) {
+                        rc = EXIT_SUCCESS;
+                        break;
                 }
 
-                if (timeout > 0) {
-                        usec_t age_usec;
+                /* wake up when "queue" file is deleted */
+                if (poll(pfd, 1, 100) > 0 && pfd[0].revents & POLLIN) {
+                        char buf[sizeof(struct inotify_event) + PATH_MAX];
 
-                        age_usec = now(CLOCK_MONOTONIC) - start_usec;
-                        if (age_usec / (1000 * 1000) >= timeout) {
-                                struct udev_list_entry *list_entry;
-
-                                if (!quiet && udev_queue_get_queued_list_entry(udev_queue) != NULL) {
-                                        log_debug("timeout waiting for udev queue");
-                                        printf("\nudevadm settle - timeout of %i seconds reached, the event queue contains:\n", timeout);
-                                        udev_list_entry_foreach(list_entry, udev_queue_get_queued_list_entry(udev_queue))
-                                                printf("  %s (%s)\n",
-                                                udev_list_entry_get_name(list_entry),
-                                                udev_list_entry_get_value(list_entry));
-                                }
-
-                                break;
-                        }
+                        read(pfd[0].fd, buf, sizeof(buf));
                 }
         }
+
 out:
         if (pfd[0].fd >= 0)
                 close(pfd[0].fd);
@@ -236,5 +149,5 @@ out:
 const struct udevadm_cmd udevadm_settle = {
         .name = "settle",
         .cmd = adm_settle,
-        .help = "wait for the event queue to finish",
+        .help = "wait for pending udev events",
 };