[PATCH] udevd - cleanup and better timeout handling

On Thu, Jan 29, 2004 at 04:55:11PM +0100, Kay Sievers wrote:
> On Thu, Jan 29, 2004 at 02:56:25AM +0100, Kay Sievers wrote:
> > On Wed, Jan 28, 2004 at 10:47:36PM +0100, Kay Sievers wrote:
> > > Oh, couldn't resist to try threads.
> > > It's a multithreaded udevd that communicates through a localhost socket.
> > > The message includes a magic with the udev version, so we don't accept
> > > older udevsend's.
> > >
> > > No need for locking, cause we can't bind two sockets on the same address.
> > > The daemon tries to connect and if it fails it starts the daemon.
> > >
> > > We create a thread for every incoming connection, handle over the socket,
> > > sort the messages in the global message queue and exit the thread.
> > > Huh, that was easy with threads :)
> > >
> > > With the addition of a message we wakeup the queue manager thread and
> > > handle timeouts or move the message to the global exec list. This wakes
> > > up the exec list manager who looks if a process is already running for this
> > > device path.
> > > If yes, the exec is delayed otherwise we create a thread that execs udev.
> > > n the background. With the return of udev we free the message and wakeup
> > > the exec list manager to look if something is pending.
> > >
> > > It is just a quick shot, cause I couldn't solve the problems with fork an
> > > scheduling and I wanted to see if I'm to stupid  :)
> > > But if anybody with a better idea or more experience with I/O scheduling
> > > we may go another way. The remaining problem is that klibc doesn't support
> > > threads.
> > >
> > > By now, we don't exec anything, it's just a sleep 3 for every exec,
> > > but you can see the queue management by watching syslog and do:
> > >
> > >   DEVPATH=/abc ACTION=add SEQNUM=0 ./udevsend /abc
>
> Next version, switched to unix domain sockets.

Next cleaned up version. Hey, nobody wants to try it :)

Works for me, It's funny if I connect/disconnect my 4in1-usb-flash-reader
every two seconds. The 2.6 usb rocks! I can connect/diconnect a hub with 3
devices plugged in every second and don't run into any problem but a _very_
big udevd queue.

1 files changed, 48 insertions, 30 deletions

diff --git a/udevsend.c b/udevsend.c
index f92ee2b5d8..6ffd68c1b7 100644
--- a/udevsend.c
+++ b/udevsend.c
@@ -32,12 +32,15 @@
 #include <unistd.h>
 #include <time.h>
 #include <wait.h>
+#include <sys/socket.h>
+#include <sys/un.h>
 
 #include "udev.h"
 #include "udev_version.h"
 #include "udevd.h"
 #include "logging.h"
 
+
 static inline char *get_action(void)
 {
 	char *action;
@@ -66,7 +69,7 @@ static int build_hotplugmsg(struct hotplug_msg *msg, char *action,
 			    char *devpath, char *subsystem, int seqnum)
 {
 	memset(msg, 0x00, sizeof(*msg));
-	msg->mtype = HOTPLUGMSGTYPE;
+	strfieldcpy(msg->magic, UDEV_MAGIC);
 	msg->seqnum = seqnum;
 	strncpy(msg->action, action, 8);
 	strncpy(msg->devpath, devpath, 128);
@@ -108,12 +111,8 @@ static int start_daemon(void)
 	return 0;
 }
 
-
 int main(int argc, char* argv[])
 {
-	int msgid;
-	key_t key;
-	struct msqid_ds msg_queue;
 	struct hotplug_msg message;
 	char *action;
 	char *devpath;
@@ -124,6 +123,8 @@ int main(int argc, char* argv[])
 	int size;
 	int loop;
 	struct timespec tspec;
+	int sock;
+	struct sockaddr_un saddr;
 
 	subsystem = argv[1];
 	if (subsystem == NULL) {
@@ -150,41 +151,58 @@ int main(int argc, char* argv[])
 	}
 	seq = atoi(seqnum);
 
-	/* create ipc message queue or get id of our existing one */
-	key = ftok(UDEVD_BIN, IPC_KEY_ID);
-	dbg("using ipc queue 0x%0x", key);
-	size =  build_hotplugmsg(&message, action, devpath, subsystem, seq);
-	msgid = msgget(key, IPC_CREAT);
-	if (msgid == -1) {
-		dbg("error open ipc queue");
+	sock = socket(AF_LOCAL, SOCK_STREAM, 0);
+	if (sock == -1) {
+		dbg("error getting socket");
 		goto exit;
 	}
 
-	/* send ipc message to the daemon */
-	retval = msgsnd(msgid, &message, size, 0);
-	if (retval == -1) {
-		dbg("error sending ipc message");
-		goto exit;
+	memset(&saddr, 0x00, sizeof(saddr));
+	saddr.sun_family = AF_LOCAL;
+	strcpy(saddr.sun_path, UDEVD_SOCKET);
+
+	/* try to connect, if it fails start daemon */
+	retval = connect(sock, &saddr, sizeof(saddr));
+	if (retval != -1) {
+		goto send;
+	} else {
+		dbg("connect failed, try starting daemon...");
+		retval = start_daemon();
+		if (retval == 0) {
+			dbg("daemon started");
+		} else {
+			dbg("error starting daemon");
+			goto exit;
+		}
 	}
 
-	/* get state of ipc queue */
+	/* try to connect while daemon to starts */
 	tspec.tv_sec = 0;
-	tspec.tv_nsec = 10000000;  /* 10 millisec */
-	loop = UDEVSEND_RETRY_COUNT;
+	tspec.tv_nsec = 100000000;  /* 100 millisec */
+	loop = UDEVSEND_CONNECT_RETRY;
 	while (loop--) {
-		retval = msgctl(msgid, IPC_STAT, &msg_queue);
-		if (retval == -1) {
-			dbg("error getting info on ipc queue");
-			goto exit;
-		}
-		if (msg_queue.msg_qnum == 0)
-			goto exit;
+		retval = connect(sock, &saddr, sizeof(saddr));
+		if (retval != -1)
+			goto send;
+		else
+			dbg("retry to connect %d",
+			    UDEVSEND_CONNECT_RETRY - loop);
 		nanosleep(&tspec, NULL);
 	}
+	dbg("error connecting to daemon, start daemon failed");
+	goto exit;
 
-	info("message is still in the ipc queue, starting daemon...");
-	retval = start_daemon();
+send:
+	size = build_hotplugmsg(&message, action, devpath, subsystem, seq);
+	retval = send(sock, &message, size, 0);
+	if (retval == -1) {
+		dbg("error sending message");
+		close (sock);
+		goto exit;
+	}
+	close (sock);
+	return 0;
 
 exit:
-	return retval;
+	return 1;
 }