udevd: allow more parameters to be set through udev.conf

Rebooting to set change the kernel command line to set some udev parameters is
inconvenient. Let's allow setting more stuff in the config file.

Also drop quotes from around "info" in udev.conf. We need to accept them for
compatibility, but there is no reason to use them.

man/udev.conf.xml

@@ -42,7 +42,7 @@
 
     <variablelist>
       <varlistentry>
-        <term><varname>udev_log</varname></term>
+        <term><varname>udev_log=</varname></term>
 
         <listitem>
           <para>The log level. Valid values are the numerical
@@ -51,6 +51,42 @@
           <option>debug</option>.</para>
         </listitem>
       </varlistentry>
+
+      <varlistentry>
+        <term><varname>children_max=</varname></term>
+
+        <listitem>
+          <para>An integer. The maximum number of events executed in parallel.</para>
+
+          <para>This is the same as the <option>--children-max=</option> option.</para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>exec_delay=</varname></term>
+
+        <listitem>
+          <para>An integer. Delay the execution of <varname>RUN</varname>
+          instructions by the given number of seconds. This option
+          might be useful when debugging system crashes during
+          coldplug caused by loading non-working kernel
+          modules.</para>
+
+          <para>This is the same as the <option>--exec-delay=</option> option.</para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>event_timeout=</varname></term>
+
+        <listitem>
+          <para>An integer. The number of seconds to wait for events to finish. After
+          this time, the event will be terminated. The default is 180 seconds.</para>
+
+          <para>This is the same as the <option>--event-timeout=</option> option.</para>
+        </listitem>
+      </varlistentry>
+
     </variablelist>
 
     <para>

src/shared/udev-util.c

@@ -6,36 +6,68 @@
 #include "alloc-util.h"
 #include "fileio.h"
 #include "log.h"
+#include "parse-util.h"
 #include "string-util.h"
 #include "udev-util.h"
+#include "udev.h"
 
-int udev_parse_config(void) {
-        _cleanup_free_ char *val = NULL;
-        const char *log;
-        size_t n;
+int udev_parse_config_full(
+                unsigned *ret_children_max,
+                usec_t *ret_exec_delay_usec,
+                usec_t *ret_event_timeout_usec) {
+
+        _cleanup_free_ char *log_val = NULL, *children_max = NULL, *exec_delay = NULL, *event_timeout = NULL;
         int r;
 
-        r = parse_env_file(NULL, "/etc/udev/udev.conf", NEWLINE, "udev_log", &val, NULL);
-        if (r == -ENOENT || !val)
+        r = parse_env_file(NULL, "/etc/udev/udev.conf", NEWLINE,
+                           "udev_log", &log_val,
+                           "children_max", &children_max,
+                           "exec_delay", &exec_delay,
+                           "event_timeout", &event_timeout,
+                           NULL);
+        if (r == -ENOENT)
                 return 0;
         if (r < 0)
                 return r;
 
-        /* unquote */
-        n = strlen(val);
-        if (n >= 2 &&
-            ((val[0] == '"' && val[n-1] == '"') ||
-             (val[0] == '\'' && val[n-1] == '\''))) {
-                val[n - 1] = '\0';
-                log = val + 1;
-        } else
-                log = val;
+        if (log_val) {
+                const char *log;
+                size_t n;
 
-        /* we set the udev log level here explicitly, this is supposed
-         * to regulate the code in libudev/ and udev/. */
-        r = log_set_max_level_from_string_realm(LOG_REALM_UDEV, log);
-        if (r < 0)
-                log_debug_errno(r, "/etc/udev/udev.conf: failed to set udev log level '%s', ignoring: %m", log);
+                /* unquote */
+                n = strlen(log_val);
+                if (n >= 2 &&
+                    ((log_val[0] == '"' && log_val[n-1] == '"') ||
+                     (log_val[0] == '\'' && log_val[n-1] == '\''))) {
+                        log_val[n - 1] = '\0';
+                        log = log_val + 1;
+                } else
+                        log = log_val;
+
+                /* we set the udev log level here explicitly, this is supposed
+                 * to regulate the code in libudev/ and udev/. */
+                r = log_set_max_level_from_string_realm(LOG_REALM_UDEV, log);
+                if (r < 0)
+                        log_debug_errno(r, "/etc/udev/udev.conf: failed to set udev log level '%s', ignoring: %m", log);
+        }
+
+        if (ret_children_max && children_max) {
+                r = safe_atou(children_max, ret_children_max);
+                if (r < 0)
+                        log_notice_errno(r, "/etc/udev/udev.conf: failed to set parse children_max=%s, ignoring: %m", children_max);
+        }
+
+        if (ret_exec_delay_usec && exec_delay) {
+                r = parse_sec(exec_delay, ret_exec_delay_usec);
+                if (r < 0)
+                        log_notice_errno(r, "/etc/udev/udev.conf: failed to set parse exec_delay=%s, ignoring: %m", exec_delay);
+        }
+
+        if (ret_event_timeout_usec && event_timeout) {
+                r = parse_sec(event_timeout, ret_event_timeout_usec);
+                if (r < 0)
+                        log_notice_errno(r, "/etc/udev/udev.conf: failed to set parse event_timeout=%s, ignoring: %m", event_timeout);
+        }
 
         return 0;
 }

src/shared/udev-util.h

@@ -1,4 +1,13 @@
 /* SPDX-License-Identifier: LGPL-2.1+ */
 #pragma once
 
-int udev_parse_config(void);
+#include "time-util.h"
+
+int udev_parse_config_full(
+                unsigned *ret_children_max,
+                usec_t *ret_exec_delay_usec,
+                usec_t *ret_event_timeout_usec);
+
+static inline int udev_parse_config(void) {
+        return udev_parse_config_full(NULL, NULL, NULL);
+}

src/udev/udev.conf

@@ -3,4 +3,7 @@
 # udevd is also started in the initrd.  When this file is modified you might
 # also want to rebuild the initrd, so that it will include the modified configuration.
 
-#udev_log="info"
+#udev_log=info
+#children_max=
+#exec_delay=
+#event_timeout=180

src/udev/udevd.c

@@ -1703,7 +1703,7 @@ int main(int argc, char *argv[]) {
         int r;
 
         log_set_target(LOG_TARGET_AUTO);
-        udev_parse_config();
+        udev_parse_config_full(&arg_children_max, &arg_exec_delay_usec, &arg_event_timeout_usec);
         log_parse_environment();
         log_open();