Merge pull request #12267 from keszybz/udev-settle-warning
Udev settle warning
This commit is contained in:
Lennart Poettering
GitHub
commit
03abeb0baf
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@ -775,6 +775,7 @@ manpages = [
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'systemd-tmpfiles-setup.service'],
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''],
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['systemd-tty-ask-password-agent', '1', [], ''],
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['systemd-udev-settle.service', '8', [], ''],
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['systemd-udevd.service',
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'8',
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['systemd-udevd',
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@ -0,0 +1,51 @@
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<?xml version='1.0'?>
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!-- SPDX-License-Identifier: LGPL-2.1+ -->
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<refentry id="systemd-udev-settle.service"
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xmlns:xi="http://www.w3.org/2001/XInclude">
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<refentryinfo>
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<title>systemd-udev-settle.service</title>
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<productname>systemd</productname>
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</refentryinfo>
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<refmeta>
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<refentrytitle>systemd-udev-settle.service</refentrytitle>
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<manvolnum>8</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>systemd-udev-settle.service</refname>
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<refpurpose>Wait for all pending udev events to be handled</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<para><filename>systemd-udev-settle.service</filename></para>
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</refsynopsisdiv>
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<refsect1><title>Description</title>
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<para>This service calls <command>udevadm settle</command> to wait until all events that have been queued
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by <citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry> have been
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processed. It is a crude way to wait until "all" hardware has been discovered. Services may pull in this
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service and order themselves after it to wait for the udev queue to be empty.</para>
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<para><emphasis>Using this service is not recommended.</emphasis> There can be no guarantee that hardware
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is fully discovered at any specific time, because the kernel does hardware detection asynchronously, and
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certain busses and devices take a very long time to become ready, and also additional hardware may be
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plugged in at any time. Instead, services should subscribe to udev events and react to any new hardware as
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it is discovered. Services that, based on configuration, expect certain devices to appear, may warn or
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report failure after a timeout. This timeout should be tailored to the hardware type. Waiting for
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<filename>systemd-udev-settle.service</filename> usually slows boot significantly, because it means waiting
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for all unrelated events too.</para>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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@ -362,6 +362,10 @@
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<xi:include href="standard-options.xml" xpointer="help" />
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</variablelist>
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<para>See
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<citerefentry><refentrytitle>systemd-udev-settle.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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for more information.</para>
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</refsect2>
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<refsect2><title>udevadm control <replaceable>option</replaceable></title>
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@ -13,10 +13,16 @@
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#include <string.h>
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#include <unistd.h>
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#include "sd-bus.h"
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#include "sd-login.h"
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#include "libudev-util.h"
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#include "string-util.h"
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#include "strv.h"
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#include "time-util.h"
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#include "udevadm.h"
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#include "udev-ctrl.h"
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#include "udevadm.h"
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#include "unit-def.h"
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#include "util.h"
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#include "virt.h"
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@ -79,6 +85,61 @@ static int parse_argv(int argc, char *argv[]) {
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return 1;
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}
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static int emit_deprecation_warning(void) {
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_cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
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_cleanup_free_ char *unit = NULL, *unit_path = NULL;
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_cleanup_strv_free_ char **a = NULL, **b = NULL;
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int r;
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r = sd_pid_get_unit(0, &unit);
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if (r < 0 || !streq(unit, "systemd-udev-settle.service"))
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return 0;
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log_notice("systemd-udev-settle.service is deprecated.");
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r = sd_bus_open_system(&bus);
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if (r < 0)
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return log_debug_errno(r, "Failed to open system bus, skipping dependency queries: %m");
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unit_path = unit_dbus_path_from_name("systemd-udev-settle.service");
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if (!unit_path)
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return -ENOMEM;
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(void) sd_bus_get_property_strv(
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bus,
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"org.freedesktop.systemd1",
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unit_path,
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"org.freedesktop.systemd1.Unit",
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"WantedBy",
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NULL,
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&a);
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(void) sd_bus_get_property_strv(
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bus,
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"org.freedesktop.systemd1",
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unit_path,
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"org.freedesktop.systemd1.Unit",
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"RequiredBy",
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NULL,
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&b);
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r = strv_extend_strv(&a, b, true);
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if (r < 0)
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return r;
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if (!strv_isempty(a)) {
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_cleanup_free_ char *t = NULL;
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t = strv_join(a, ", ");
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if (!t)
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return -ENOMEM;
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log_notice("Hint: please fix %s not to pull it in.", t);
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}
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return 0;
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}
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int settle_main(int argc, char *argv[], void *userdata) {
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_cleanup_(udev_queue_unrefp) struct udev_queue *queue = NULL;
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struct pollfd pfd;
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@ -128,6 +189,8 @@ int settle_main(int argc, char *argv[], void *userdata) {
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.fd = r,
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};
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(void) emit_deprecation_warning();
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for (;;) {
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if (arg_exists && access(arg_exists, F_OK) >= 0)
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return 0;
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@ -13,7 +13,7 @@
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[Unit]
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Description=udev Wait for Complete Device Initialization
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Documentation=man:udev(7) man:systemd-udevd.service(8)
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Documentation=man:systemd-udev-settle.service(8)
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DefaultDependencies=no
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Wants=systemd-udevd.service
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After=systemd-udev-trigger.service
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