udevd: add --debug-trace option

3 files changed, 31 insertions, 2 deletions

diff --git a/udevd.8 b/udevd.8
index aef2090236..cc724dceda 100644
--- a/udevd.8
+++ b/udevd.8
@@ -14,7 +14,7 @@
 udevd \- event managing daemon
 .SH "SYNOPSIS"
 .HP 6
-\fBudevd\fR [\fB\-\-daemon\fR] [\fB\-\-verbose\fR] [\fB\-\-help\fR]
+\fBudevd\fR [\fB\-\-daemon\fR] [\fB\-\-debug\-trace\fR] [\fB\-\-verbose\fR] [\fB\-\-help\fR]
 .HP 20
 \fBudevcontrol \fR\fB\fIcommand\fR\fR
 .SH "DESCRIPTION"
@@ -25,6 +25,9 @@ udevd listens to kernel uevents and passes the incoming events to udev. It ensur
 \fB\-\-daemon\fR
 Detach and run in the background.
 .TP 3n
+\fB\-\-debug\-trace\fR
+Run all events completely serialized. This may be useful if udev triggers actions or loads kernel modules which cause problems and a slow but continiuous operation is needed, where no events are processed in parallel.
+.TP 3n
 \fB\-\-verbose\fR
 Print log messages to stdout.
 .TP 3n
diff --git a/udevd.c b/udevd.c
index eb632bd852..3adedac080 100644
--- a/udevd.c
+++ b/udevd.c
@@ -45,6 +45,7 @@
 #include "udevd.h"
 #include "udev_selinux.h"
 
+static int debug_trace;
 static int verbose;
 
 static struct udev_rules rules;
@@ -307,6 +308,15 @@ static void msg_queue_insert(struct udevd_uevent_msg *msg)
 
 	export_event_state(msg, EVENT_QUEUED);
 
+	/* run one event after the other in debug mode */
+	if (debug_trace) {
+		list_add_tail(&msg->node, &running_list);
+		udev_event_run(msg);
+		waitpid(msg->pid, NULL, 0);
+		msg_queue_delete(msg);
+		return;
+	}
+
 	/* run all events with a timeout set immediately */
 	if (msg->timeout != 0) {
 		list_add_tail(&msg->node, &running_list);
@@ -930,6 +940,7 @@ int main(int argc, char *argv[], char *envp[])
 	int option;
 	static const struct option options[] = {
 		{ "daemon", 0, NULL, 'd' },
+		{ "debug-trace", 0, NULL, 't' },
 		{ "verbose", 0, NULL, 'v' },
 		{ "help", 0, NULL, 'h' },
 		{}
@@ -952,13 +963,16 @@ int main(int argc, char *argv[], char *envp[])
 		case 'd':
 			daemonize = 1;
 			break;
+		case 't':
+			debug_trace = 1;
+			break;
 		case 'v':
 			verbose = 1;
 			if (udev_log_priority < LOG_INFO)
 				udev_log_priority = LOG_INFO;
 			break;
 		case 'h':
-			printf("Usage: udevd [--help] [--daemon] [--verbose]\n");
+			printf("Usage: udevd [--help] [--daemon] [--debug-trace] [--verbose]\n");
 			goto exit;
 		default:
 			goto exit;
@@ -1128,6 +1142,8 @@ int main(int argc, char *argv[], char *envp[])
 	/* export log_priority , as called programs may want to follow that setting */
 	sprintf(udev_log, "UDEV_LOG=%i", udev_log_priority);
 	putenv(udev_log);
+	if (debug_trace)
+		putenv("DEBUG=1");
 
 	maxfd = udevd_sock;
 	maxfd = UDEV_MAX(maxfd, uevent_netlink_sock);
diff --git a/udevd.xml b/udevd.xml
index cc2a1bcd22..938707bee1 100644
--- a/udevd.xml
+++ b/udevd.xml
@@ -26,6 +26,7 @@
         <cmdsynopsis>
           <command>udevd</command>
           <arg><option>--daemon</option></arg>
+          <arg><option>--debug-trace</option></arg>
           <arg><option>--verbose</option></arg>
           <arg><option>--help</option></arg>
         </cmdsynopsis>
@@ -49,6 +50,15 @@
             </listitem>
           </varlistentry>
           <varlistentry>
+            <term><option>--debug-trace</option></term>
+            <listitem>
+              <para>Run all events completely serialized. This may be useful if udev triggers
+              actions or loads kernel modules which cause problems and a slow but continiuous
+              operation is needed, where no events are processed in parallel.
+              </para>
+            </listitem>
+          </varlistentry>
+          <varlistentry>
             <term><option>--verbose</option></term>
             <listitem>
               <para>Print log messages to stdout.</para>