[PATCH] use uevents in udevd

[PATCH] use uevents in udevd

[Hannes Reinecke]

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Hi all,

this patch adds the capabilities to read uevents directly from the 
kernel socket (CONFIG_KOBJECT_UEVENT=y).
The old behaviour is left in place, as with this we can still send 
events manually.

And I've added a command-line option '-d' to start udevd as a daemon.
Now we can do

/sbin/udevd -p
echo -n "" > /proc/sys/kernel/hotplug

no need for udevsend anymore.
Plus we can finally do a load-limit for hotplug events.

Comments welcome.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke			hare@suse.de
SuSE Linux AG				S390 & zSeries
Maxfeldstraße 5				+49 911 74053 688
90409 Nürnberg				http://www.suse.de

[-- Attachment #2: udevd-uevent.patch --]
[-- Type: text/x-patch, Size: 6743 bytes --]

===== udevd.c 1.59 vs edited =====
--- 1.59/udevd.c	2005-01-04 21:37:50 +01:00
+++ edited/udevd.c	2005-01-14 11:13:51 +01:00
@@ -35,6 +35,7 @@
 #include <fcntl.h>
 #include <sys/sysinfo.h>
 #include <sys/stat.h>
+#include <linux/netlink.h>
 
 #include "list.h"
 #include "udev.h"
@@ -43,8 +44,14 @@
 #include "udevd.h"
 #include "logging.h"
 
+/* Older header files do not define this */
+#ifndef NETLINK_KOBJECT_UEVENT
+#define NETLINK_KOBJECT_UEVENT 15
+#endif
+
 /* global variables*/
 static int udevsendsock;
+static int ueventsock;
 
 static int pipefds[2];
 static long startup_time;
@@ -376,6 +383,83 @@
 	return msg;
 }
 
+#define UEVENT_BUFFER_SIZE		1024
+#define OBJECT_SIZE			512
+
+/* receive the kernel user event message and do some sanity checks */
+static struct hotplug_msg *get_uevent_msg(void)
+{
+	struct hotplug_msg *msg;
+	int bufpos;
+	int i;
+	ssize_t size;
+	char *pos;
+	static char buffer[UEVENT_BUFFER_SIZE + OBJECT_SIZE];
+
+	size = recv(ueventsock, &buffer, sizeof(buffer),0);
+	if (size <  0) {
+		if (errno != EINTR)
+			dbg("unable to receive udevsend message");
+		return NULL;
+	}
+
+	if ((size_t)size > sizeof(buffer)-1)
+	    size = sizeof(buffer)-1;
+	
+	buffer[size] = '\0';
+
+	dbg("uevent_size=%i", size);
+	msg = malloc(sizeof(struct hotplug_msg) + size);
+	if (msg == NULL)
+		return NULL;
+
+	memset(msg, 0x00, sizeof(struct hotplug_msg) + size);
+
+	/* copy environment buffer and reconstruct envp */
+	memcpy(msg->envbuf, buffer, size);
+
+	/* save start of payload */
+	bufpos = strlen(buffer) + 1;
+
+	/* action string */
+	msg->action = msg->envbuf;
+	pos = strchr(msg->envbuf, '@');
+	if (!pos) {
+		free(msg);
+		return NULL;
+	}
+	pos[0] = '\0';
+
+	/* sysfs path */
+	msg->devpath = &pos[1];
+
+
+	for (i = 0; (bufpos < size) && (i < HOTPLUG_NUM_ENVP-2); i++) {
+		int keylen;
+		char *key;
+
+		key = &msg->envbuf[bufpos];
+		keylen = strlen(key);
+		msg->envp[i] = key;
+		bufpos += keylen + 1;
+		dbg("add '%s' to msg.envp[%i]", msg->envp[i], i);
+
+		/* remember some keys for further processing */
+		if (strncmp(key, "SUBSYSTEM=", 10) == 0)
+			msg->subsystem = &key[10];
+
+		if (strncmp(key, "SEQNUM=", 7) == 0)
+			msg->seqnum = strtoull(&key[7], NULL, 10);
+
+		if (strncmp(key, "PHYSDEVPATH=", 12) == 0)
+			msg->physdevpath = &key[12];
+	}
+	msg->envp[i++] = "UDEVD_EVENT=1";
+	msg->envp[i] = NULL;
+
+	return msg;
+}
+
 static void asmlinkage sig_handler(int signum)
 {
 	int rc;
@@ -453,17 +537,114 @@
 	}
 }
 
+static int init_udevsend_socket(void)
+{
+	struct sockaddr_un saddr;
+	socklen_t addrlen;
+	const int feature_on = 1;
+	int retval;
+
+	memset(&saddr, 0x00, sizeof(saddr));
+	saddr.sun_family = AF_LOCAL;
+	/* use abstract namespace for socket path */
+	strcpy(&saddr.sun_path[1], UDEVD_SOCK_PATH);
+	addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(saddr.sun_path+1) + 1;
+
+	udevsendsock = socket(AF_LOCAL, SOCK_DGRAM, 0);
+	if (udevsendsock == -1) {
+		dbg("error getting socket, %s", strerror(errno));
+		return -1;
+	}
+
+	/* the bind takes care of ensuring only one copy running */
+	retval = bind(udevsendsock, (struct sockaddr *) &saddr, addrlen);
+	if (retval < 0) {
+		dbg("bind failed, %s", strerror(errno));
+		close(udevsendsock);
+		return -1;
+	}
+
+	/* enable receiving of the sender credentials */
+	setsockopt(udevsendsock, SOL_SOCKET, SO_PASSCRED, &feature_on, sizeof(feature_on));
+
+	return 0;
+}
+
+static int init_uevent_socket(void)
+{
+	struct sockaddr_nl snl;
+	int retval;
+
+	memset(&snl, 0x00, sizeof(struct sockaddr_nl));
+	snl.nl_family = AF_NETLINK;
+	snl.nl_pid = getpid();
+	snl.nl_groups = 0xffffffff;
+
+	ueventsock = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
+	if (ueventsock == -1) {
+		dbg("error getting socket, %s", strerror(errno));
+		return -1;
+	}
+
+	retval = bind(ueventsock, (struct sockaddr *) &snl,
+		      sizeof(struct sockaddr_nl));
+	if (retval < 0) {
+		dbg("bind failed, %s", strerror(errno));
+		close(ueventsock);
+		ueventsock = -1;
+		return -1;
+	}
+
+	return 0;
+}
+
+static int start_daemon(char *pathname)
+{
+	pid_t pid;
+	pid_t child_pid;
+	char *const argv[] = { "udevd", NULL };
+	char *const envp[] = { NULL };
+
+	pid = fork();
+	switch (pid) {
+	case 0:
+		/* helper child */
+		child_pid = fork();
+		switch (child_pid) {
+		case 0:
+			/* daemon with empty environment */
+			execve(pathname, argv, envp);
+			dbg("exec of daemon failed");
+			_exit(1);
+		case -1:
+			dbg("fork of daemon failed");
+			return -1;
+		default:
+			exit(0);
+		}
+		break;
+	case -1:
+		dbg("fork of helper failed");
+		return -1;
+	default:
+		waitpid(pid, NULL, 0);
+	}
+	return 0;
+}
+
 int main(int argc, char *argv[], char *envp[])
 {
 	struct sysinfo info;
 	int maxsockplus;
-	struct sockaddr_un saddr;
-	socklen_t addrlen;
 	int retval, fd;
-	const int feature_on = 1;
 	struct sigaction act;
 	fd_set readfds;
 
+	if (argc > 1 && strncmp(argv[1],"-d",2)) {
+		retval = start_daemon(argv[0]);
+		return retval;
+	}
+
 	logging_init("udevd");
 	dbg("version %s", UDEV_VERSION);
 
@@ -529,29 +710,19 @@
 	sigaction(SIGALRM, &act, NULL);
 	sigaction(SIGCHLD, &act, NULL);
 
-	memset(&saddr, 0x00, sizeof(saddr));
-	saddr.sun_family = AF_LOCAL;
-	/* use abstract namespace for socket path */
-	strcpy(&saddr.sun_path[1], UDEVD_SOCK_PATH);
-	addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(saddr.sun_path+1) + 1;
-
-	udevsendsock = socket(AF_LOCAL, SOCK_DGRAM, 0);
-	if (udevsendsock == -1) {
-		dbg("error getting socket, exit");
-		goto exit;
+	if (init_uevent_socket() < 0) {
+		dbg("uevent socket not available");
 	}
 
-	/* the bind takes care of ensuring only one copy running */
-	retval = bind(udevsendsock, (struct sockaddr *) &saddr, addrlen);
-	if (retval < 0) {
-		dbg("bind failed, exit");
-		close(udevsendsock);
+	if (init_udevsend_socket() < 0) {
+		if (errno == EADDRINUSE)
+			dbg("another udevd is running, exit");
+		else
+			dbg("error initialising udevsend socket: %s",
+			    strerror(errno));
 		goto exit;
 	}
 
-	/* enable receiving of the sender credentials */
-	setsockopt(udevsendsock, SOL_SOCKET, SO_PASSCRED, &feature_on, sizeof(feature_on));
-
 	/* possible override of udev binary, used for testing */
 	udev_bin = getenv("UDEV_BIN");
 	if (udev_bin != NULL)
@@ -565,6 +736,8 @@
 
 	FD_ZERO(&readfds);
 	FD_SET(udevsendsock, &readfds);
+	if (ueventsock != -1)
+		FD_SET(ueventsock, &readfds);
 	FD_SET(pipefds[0], &readfds);
 	maxsockplus = udevsendsock+1;
 	while (1) {
@@ -581,6 +754,12 @@
 
 		if (FD_ISSET(udevsendsock, &workreadfds)) {
 			msg = get_udevsend_msg();
+			if (msg)
+				msg_queue_insert(msg);
+		}
+
+		if (FD_ISSET(ueventsock, &workreadfds)) {
+			msg = get_uevent_msg();
 			if (msg)
 				msg_queue_insert(msg);
 		}

Re: [PATCH] use uevents in udevd

[Marco d'Itri]

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On Jan 14, Hannes Reinecke <hare@suse.de> wrote:

> Comments welcome.
Nice work.
How can the init scripts determine if support for uevents is available?

-- 
ciao,
Marco

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Re: [PATCH] use uevents in udevd

[Hannes Reinecke]

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Marco d'Itri wrote:
> On Jan 14, Hannes Reinecke <hare@suse.de> wrote:
> 
> 
>>Comments welcome.
> 
> Nice work.
> How can the init scripts determine if support for uevents is available?
> 
Good question. Asked myself the same one just now.
I couldn't figure out whether this information is exported from the 
kernel directly, so that leaves two possibilities:

- check /proc/config.gz for CONFIG_KOBJECT_UEVENT
   (if /proc/config.gz is available)
- use a program to check for it (like the attached one).

HTH,

Hannes
-- 
Dr. Hannes Reinecke			hare@suse.de
SuSE Linux AG				S390 & zSeries
Maxfeldstraße 5				+49 911 74053 688
90409 Nürnberg				http://www.suse.de

[-- Attachment #2: uevent_check.c --]
[-- Type: text/x-csrc, Size: 1716 bytes --]

/*
 * uevent_check.c - check for uevent socket
 *
 * based on uevent_listen.c
 *
 * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
 * Copyright (C) 2004 Hannes Reinecke <hare@suse.de>
 *
 *	This program is free software; you can redistribute it and/or modify it
 *	under the terms of the GNU General Public License as published by the
 *	Free Software Foundation version 2 of the License.
 *
 *	This program is distributed in the hope that it will be useful, but
 *	WITHOUT ANY WARRANTY; without even the implied warranty of
 *	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *	General Public License for more details.
 *
 *	You should have received a copy of the GNU General Public License along
 *	with this program; if not, write to the Free Software Foundation, Inc.,
 *	675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <time.h>
#include <sys/socket.h>
#include <sys/user.h>
#include <asm/types.h>
#include <linux/netlink.h>

int main(int argc, char *argv[])
{
	int sock;
	struct sockaddr_nl snl;
	int retval;

	if (getuid() != 0) {
		fprintf(stderr,"need to be root, exit\n");
		exit(0);
	}

	memset(&snl, 0x00, sizeof(struct sockaddr_nl));
	snl.nl_family = AF_NETLINK;
	snl.nl_pid = getpid();
	snl.nl_groups = 0xffffffff;

	sock = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
	if (sock == -1) {
		fprintf(stderr,"error getting socket, exit\n");
		exit(1);
	}

	retval = bind(sock, (struct sockaddr *) &snl,
		      sizeof(struct sockaddr_nl));
	if (retval < 0) {
		fprintf("bind failed, exit\n");
		exit(1);
	}
	fprintf(stderr,"uevent socket available");
	exit(0);
}

Re: [PATCH] use uevents in udevd

[Kay Sievers]

On Fri, 2005-01-14 at 11:22 +0100, Hannes Reinecke wrote:
> Hi all,
> 
> this patch adds the capabilities to read uevents directly from the 
> kernel socket (CONFIG_KOBJECT_UEVENT=y).

Heh, I just split up the message handling in udevd last week to possibly
plug in a second source of events. Nice work!

Shouldn't we ignore events with a SEQNUM from udevsend, if we get the
first one from the uevent?

> The old behaviour is left in place, as with this we can still send 
> events manually.

./drivers/input/input.c
./drivers/pnp/pnpbios/core.c
./drivers/s390/crypto/z90main.c

are still "broken" from that view. They bypass the driver core and don't
send any uevent.

> And I've added a command-line option '-d' to start udevd as a daemon.

It is already running, right? We should read /sys/kernel/hotplug_seqnum
and initialize the next expected event number too, if the self-daemonize
is needed.

> Now we can do
> /sbin/udevd -p

-p? :)

> echo -n "" > /proc/sys/kernel/hotplug

This will break the complete input layer until now! :(

> no need for udevsend anymore.
> Plus we can finally do a load-limit for hotplug events.

Thanks,
Kay



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Re: [PATCH] use uevents in udevd

[Marco d'Itri]

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On Jan 14, Hannes Reinecke <hare@suse.de> wrote:

> - check /proc/config.gz for CONFIG_KOBJECT_UEVENT
>   (if /proc/config.gz is available)
Not acceptable for a distribution script.

> - use a program to check for it (like the attached one).
It's yet another binary to install in the initrd etc... What about
integrating it in udevd? It could exit with a specific error value if
uevents are not available, and most of the code is already there.

-- 
ciao,
Marco

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Re: [PATCH] use uevents in udevd

[Hannes Reinecke]

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Kay Sievers wrote:
> On Fri, 2005-01-14 at 11:22 +0100, Hannes Reinecke wrote:
> 
>>Hi all,
>>
>>this patch adds the capabilities to read uevents directly from the 
>>kernel socket (CONFIG_KOBJECT_UEVENT=y).
> 
> 
> Heh, I just split up the message handling in udevd last week to possibly
> plug in a second source of events. Nice work!
> 
> Shouldn't we ignore events with a SEQNUM from udevsend, if we get the
> first one from the uevent?
> 
Indeed we should. I fixed the patch accordingly.
(Hopefully correct; the list is scanned backwards, right?)

> 
>>The old behaviour is left in place, as with this we can still send 
>>events manually.
> 
> 
> ./drivers/input/input.c
> ./drivers/pnp/pnpbios/core.c
> ./drivers/s390/crypto/z90main.c
> 
> are still "broken" from that view. They bypass the driver core and don't
> send any uevent.
> 
Oh s**t. Still?

Time to lean on Vojtech to fix the input layer.
Martin promised that z90main will be fixed, so no worries about that 
one. Will have to check pnpbios.

> 
>>And I've added a command-line option '-d' to start udevd as a daemon.
> 
> 
> It is already running, right? We should read /sys/kernel/hotplug_seqnum
> and initialize the next expected event number too, if the self-daemonize
> is needed.
> 
Well, no. At least not necessarily.
And doesn't matter anyway as it will exit if another daemon is already 
running.
-> There can be only one <-

How does this expected event number thingie work?
If we're presetting the expected number, what will happen to events 
which might be fed from udevsend after startup of udevd?
Especially interesting if the udevinitd approach is used ...

> 
>>Now we can do
>>/sbin/udevd -p
> 
> 
> -p? :)
> 
:-)
-ENOCOFFEE

Cheers,

Hannes
-- 
Dr. Hannes Reinecke			hare@suse.de
SuSE Linux AG				S390 & zSeries
Maxfeldstraße 5				+49 911 74053 688
90409 Nürnberg				http://www.suse.de

[-- Attachment #2: udevd-uevent.patch --]
[-- Type: text/x-patch, Size: 7073 bytes --]

===== udevd.c 1.59 vs edited =====
--- 1.59/udevd.c	2005-01-04 21:37:50 +01:00
+++ edited/udevd.c	2005-01-14 12:21:25 +01:00
@@ -35,6 +35,7 @@
 #include <fcntl.h>
 #include <sys/sysinfo.h>
 #include <sys/stat.h>
+#include <linux/netlink.h>
 
 #include "list.h"
 #include "udev.h"
@@ -43,8 +44,14 @@
 #include "udevd.h"
 #include "logging.h"
 
+/* Older header files do not define this */
+#ifndef NETLINK_KOBJECT_UEVENT
+#define NETLINK_KOBJECT_UEVENT 15
+#endif
+
 /* global variables*/
 static int udevsendsock;
+static int ueventsock;
 
 static int pipefds[2];
 static long startup_time;
@@ -110,6 +117,11 @@
 
 	/* sort message by sequence number into list */
 	list_for_each_entry_reverse(loop_msg, &msg_list, list)
+		if (loop_msg->seqnum == msg->seqnum) {
+			dbg("duplicate message seq %llu, ignoring", 
+			    msg->seqnum);
+			return;
+		}
 		if (loop_msg->seqnum < msg->seqnum)
 			break;
 
@@ -376,6 +388,83 @@
 	return msg;
 }
 
+#define UEVENT_BUFFER_SIZE		1024
+#define OBJECT_SIZE			512
+
+/* receive the kernel user event message and do some sanity checks */
+static struct hotplug_msg *get_uevent_msg(void)
+{
+	struct hotplug_msg *msg;
+	int bufpos;
+	int i;
+	ssize_t size;
+	char *pos;
+	static char buffer[UEVENT_BUFFER_SIZE + OBJECT_SIZE];
+
+	size = recv(ueventsock, &buffer, sizeof(buffer),0);
+	if (size <  0) {
+		if (errno != EINTR)
+			dbg("unable to receive udevsend message");
+		return NULL;
+	}
+
+	if ((size_t)size > sizeof(buffer)-1)
+	    size = sizeof(buffer)-1;
+	
+	buffer[size] = '\0';
+
+	dbg("uevent_size=%i", size);
+	msg = malloc(sizeof(struct hotplug_msg) + size);
+	if (msg == NULL)
+		return NULL;
+
+	memset(msg, 0x00, sizeof(struct hotplug_msg) + size);
+
+	/* copy environment buffer and reconstruct envp */
+	memcpy(msg->envbuf, buffer, size);
+
+	/* save start of payload */
+	bufpos = strlen(buffer) + 1;
+
+	/* action string */
+	msg->action = msg->envbuf;
+	pos = strchr(msg->envbuf, '@');
+	if (!pos) {
+		free(msg);
+		return NULL;
+	}
+	pos[0] = '\0';
+
+	/* sysfs path */
+	msg->devpath = &pos[1];
+
+
+	for (i = 0; (bufpos < size) && (i < HOTPLUG_NUM_ENVP-2); i++) {
+		int keylen;
+		char *key;
+
+		key = &msg->envbuf[bufpos];
+		keylen = strlen(key);
+		msg->envp[i] = key;
+		bufpos += keylen + 1;
+		dbg("add '%s' to msg.envp[%i]", msg->envp[i], i);
+
+		/* remember some keys for further processing */
+		if (strncmp(key, "SUBSYSTEM=", 10) == 0)
+			msg->subsystem = &key[10];
+
+		if (strncmp(key, "SEQNUM=", 7) == 0)
+			msg->seqnum = strtoull(&key[7], NULL, 10);
+
+		if (strncmp(key, "PHYSDEVPATH=", 12) == 0)
+			msg->physdevpath = &key[12];
+	}
+	msg->envp[i++] = "UDEVD_EVENT=1";
+	msg->envp[i] = NULL;
+
+	return msg;
+}
+
 static void asmlinkage sig_handler(int signum)
 {
 	int rc;
@@ -453,17 +542,114 @@
 	}
 }
 
+static int init_udevsend_socket(void)
+{
+	struct sockaddr_un saddr;
+	socklen_t addrlen;
+	const int feature_on = 1;
+	int retval;
+
+	memset(&saddr, 0x00, sizeof(saddr));
+	saddr.sun_family = AF_LOCAL;
+	/* use abstract namespace for socket path */
+	strcpy(&saddr.sun_path[1], UDEVD_SOCK_PATH);
+	addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(saddr.sun_path+1) + 1;
+
+	udevsendsock = socket(AF_LOCAL, SOCK_DGRAM, 0);
+	if (udevsendsock == -1) {
+		dbg("error getting socket, %s", strerror(errno));
+		return -1;
+	}
+
+	/* the bind takes care of ensuring only one copy running */
+	retval = bind(udevsendsock, (struct sockaddr *) &saddr, addrlen);
+	if (retval < 0) {
+		dbg("bind failed, %s", strerror(errno));
+		close(udevsendsock);
+		return -1;
+	}
+
+	/* enable receiving of the sender credentials */
+	setsockopt(udevsendsock, SOL_SOCKET, SO_PASSCRED, &feature_on, sizeof(feature_on));
+
+	return 0;
+}
+
+static int init_uevent_socket(void)
+{
+	struct sockaddr_nl snl;
+	int retval;
+
+	memset(&snl, 0x00, sizeof(struct sockaddr_nl));
+	snl.nl_family = AF_NETLINK;
+	snl.nl_pid = getpid();
+	snl.nl_groups = 0xffffffff;
+
+	ueventsock = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
+	if (ueventsock == -1) {
+		dbg("error getting socket, %s", strerror(errno));
+		return -1;
+	}
+
+	retval = bind(ueventsock, (struct sockaddr *) &snl,
+		      sizeof(struct sockaddr_nl));
+	if (retval < 0) {
+		dbg("bind failed, %s", strerror(errno));
+		close(ueventsock);
+		ueventsock = -1;
+		return -1;
+	}
+
+	return 0;
+}
+
+static int start_daemon(char *pathname)
+{
+	pid_t pid;
+	pid_t child_pid;
+	char *const argv[] = { "udevd", NULL };
+	char *const envp[] = { "UDEVD_DAEMON=1", NULL };
+
+	pid = fork();
+	switch (pid) {
+	case 0:
+		/* helper child */
+		child_pid = fork();
+		switch (child_pid) {
+		case 0:
+			/* daemon with empty environment */
+			execve(pathname, argv, envp);
+			dbg("exec of daemon failed");
+			_exit(1);
+		case -1:
+			dbg("fork of daemon failed");
+			return -1;
+		default:
+			exit(0);
+		}
+		break;
+	case -1:
+		dbg("fork of helper failed");
+		return -1;
+	default:
+		waitpid(pid, NULL, 0);
+	}
+	return 0;
+}
+
 int main(int argc, char *argv[], char *envp[])
 {
 	struct sysinfo info;
 	int maxsockplus;
-	struct sockaddr_un saddr;
-	socklen_t addrlen;
 	int retval, fd;
-	const int feature_on = 1;
 	struct sigaction act;
 	fd_set readfds;
 
+	if (argc > 1 && strncmp(argv[1],"-d",2)) {
+		retval = start_daemon(argv[0]);
+		return retval;
+	}
+
 	logging_init("udevd");
 	dbg("version %s", UDEV_VERSION);
 
@@ -529,29 +715,19 @@
 	sigaction(SIGALRM, &act, NULL);
 	sigaction(SIGCHLD, &act, NULL);
 
-	memset(&saddr, 0x00, sizeof(saddr));
-	saddr.sun_family = AF_LOCAL;
-	/* use abstract namespace for socket path */
-	strcpy(&saddr.sun_path[1], UDEVD_SOCK_PATH);
-	addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(saddr.sun_path+1) + 1;
-
-	udevsendsock = socket(AF_LOCAL, SOCK_DGRAM, 0);
-	if (udevsendsock == -1) {
-		dbg("error getting socket, exit");
-		goto exit;
+	if (init_uevent_socket() < 0) {
+		dbg("uevent socket not available");
 	}
 
-	/* the bind takes care of ensuring only one copy running */
-	retval = bind(udevsendsock, (struct sockaddr *) &saddr, addrlen);
-	if (retval < 0) {
-		dbg("bind failed, exit");
-		close(udevsendsock);
+	if (init_udevsend_socket() < 0) {
+		if (errno == EADDRINUSE)
+			dbg("another udevd is running, exit");
+		else
+			dbg("error initialising udevsend socket: %s",
+			    strerror(errno));
 		goto exit;
 	}
 
-	/* enable receiving of the sender credentials */
-	setsockopt(udevsendsock, SOL_SOCKET, SO_PASSCRED, &feature_on, sizeof(feature_on));
-
 	/* possible override of udev binary, used for testing */
 	udev_bin = getenv("UDEV_BIN");
 	if (udev_bin != NULL)
@@ -565,6 +741,8 @@
 
 	FD_ZERO(&readfds);
 	FD_SET(udevsendsock, &readfds);
+	if (ueventsock != -1)
+		FD_SET(ueventsock, &readfds);
 	FD_SET(pipefds[0], &readfds);
 	maxsockplus = udevsendsock+1;
 	while (1) {
@@ -581,6 +759,12 @@
 
 		if (FD_ISSET(udevsendsock, &workreadfds)) {
 			msg = get_udevsend_msg();
+			if (msg)
+				msg_queue_insert(msg);
+		}
+
+		if (FD_ISSET(ueventsock, &workreadfds)) {
+			msg = get_uevent_msg();
 			if (msg)
 				msg_queue_insert(msg);
 		}

Re: [PATCH] use uevents in udevd

[Hannes Reinecke]

Marco d'Itri wrote:
> On Jan 14, Hannes Reinecke <hare@suse.de> wrote:
> 
> 
>>- check /proc/config.gz for CONFIG_KOBJECT_UEVENT
>>  (if /proc/config.gz is available)
> 
> Not acceptable for a distribution script.
> 
> 
Yeah, I know.

>>- use a program to check for it (like the attached one).
> 
> It's yet another binary to install in the initrd etc... What about
> integrating it in udevd? It could exit with a specific error value if
> uevents are not available, and most of the code is already there.
> 
Well, the main point of the udevd patch is that it's backwards 
compatible. So it'll start regardless whether uevent sockets are 
available or not.
And it's not a clever idea to use udevsend for this task, either, as we 
will have to use it to feed manual events to udevd.
So just exiting udevsend with an error code if uevent sockets are 
available it IMHO not possible.

But I might be convinced otherwise.

And yes, I also don't like the 'yet another binary' idea.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke			hare@suse.de
SuSE Linux AG				S390 & zSeries
Maxfeldstraße 5				+49 911 74053 688
90409 Nürnberg				http://www.suse.de


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Re: [PATCH] use uevents in udevd

[Marco d'Itri]

[-- Attachment #1: Type: text/plain, Size: 334 bytes --]

On Jan 14, Hannes Reinecke <hare@suse.de> wrote:

> Well, the main point of the udevd patch is that it's backwards 
> compatible. So it'll start regardless whether uevent sockets are 
> available or not.
But I did understand that you have to start it with -d to use uevents,
so where is the compatibility?

-- 
ciao,
Marco

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 189 bytes --]

Re: [PATCH] use uevents in udevd

[Kay Sievers]

On Fri, 2005-01-14 at 12:22 +0100, Hannes Reinecke wrote: 
> Kay Sievers wrote:
> > On Fri, 2005-01-14 at 11:22 +0100, Hannes Reinecke wrote:
> > Shouldn't we ignore events with a SEQNUM from udevsend, if we get the
> > first one from the uevent?
> > 
> Indeed we should. I fixed the patch accordingly.
> (Hopefully correct; the list is scanned backwards, right?)

We can't be sure that the message coming in from netlink is still in the
queue. I think we should just set a flag with the first valid netlink
message we receive and skip all udevsend messages with a SEQNUM set from
that on. 
 
> > ./drivers/input/input.c
> > ./drivers/pnp/pnpbios/core.c
> > ./drivers/s390/crypto/z90main.c
> > 
> > are still "broken" from that view. They bypass the driver core and don't
> > send any uevent.
> > 
> Oh s**t. Still?
> 
> Time to lean on Vojtech to fix the input layer.
> Martin promised that z90main will be fixed, so no worries about that 
> one. Will have to check pnpbios.

> >>And I've added a command-line option '-d' to start udevd as a daemon.
> > 
> > 
> > It is already running, right? We should read /sys/kernel/hotplug_seqnum
> > and initialize the next expected event number too, if the self-daemonize
> > is needed.
> > 
> Well, no. At least not necessarily.
> And doesn't matter anyway as it will exit if another daemon is already 
> running.
> -> There can be only one <-

I mean: Why do you want to start it manually? The fist event will do
this normally. But you are right, if one want's to start it, it's better
than ./udevd&.

> How does this expected event number thingie work?

The daemon has a state which event is the next expected. If we get
something different from the expected number we will wait until a
timeout.

If you kill it and restart it or just start it by hand, we have a good
chance to set the correct next_expected number from the kernel.

> If we're presetting the expected number, what will happen to events 
> which might be fed from udevsend after startup of udevd?

It's slippery yes, but initializing it may be slightly better than
not to read it. :) It's not really important anymore as the next version
of udev will have a special startup event timout of 2sec. But the
current one has a 10sec timeout which e.g. breaks the firmware loader
which also has a 10sec timeout. :)

> Especially interesting if the udevinitd approach is used ...

In this case we need to do more special handling when we receive the queue
from initramfs, so we can handle that, right?

Thanks,
Kay



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Re: [PATCH] use uevents in udevd

[Kay Sievers]

On Fri, 2005-01-14 at 11:55 +0100, Hannes Reinecke wrote:
> Marco d'Itri wrote:
> > On Jan 14, Hannes Reinecke <hare@suse.de> wrote:
> > 
> > 
> >>Comments welcome.
> > 
> > Nice work.
> > How can the init scripts determine if support for uevents is available?
> > 
> Good question. Asked myself the same one just now.
> I couldn't figure out whether this information is exported from the 
> kernel directly, so that leaves two possibilities:
> 
> - check /proc/config.gz for CONFIG_KOBJECT_UEVENT
>    (if /proc/config.gz is available)
> - use a program to check for it (like the attached one).

Did you try the program on a kernel without uevents. I think you can
bind successful to all the 32 netlink sockets even without a "sender".

Thanks,
Kay



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Re: [PATCH] use uevents in udevd

[Arnd Bergmann]

[-- Attachment #1: Type: text/plain, Size: 363 bytes --]

On Freedag 14 Januar 2005 12:22, Hannes Reinecke wrote:
> Martin promised that z90main will be fixed, so no worries about that 
> one. Will have to check pnpbios.

I think z90crypt is clean already, because Z90CRYPT_USE_HOTPLUG is never
defined anyway. The option is only there because the source used to be kept
in sync with the 2.4 version.

	Arnd <><

[-- Attachment #2: signature --]
[-- Type: application/pgp-signature, Size: 189 bytes --]

Re: [PATCH] use uevents in udevd

[Hannes Reinecke]

Kay Sievers wrote:
> On Fri, 2005-01-14 at 11:55 +0100, Hannes Reinecke wrote:
> 
>>Marco d'Itri wrote:
>>
>>>On Jan 14, Hannes Reinecke <hare@suse.de> wrote:
>>>
>>>
>>>
>>>>Comments welcome.
>>>
>>>Nice work.
>>>How can the init scripts determine if support for uevents is available?
>>>
>>
>>Good question. Asked myself the same one just now.
>>I couldn't figure out whether this information is exported from the 
>>kernel directly, so that leaves two possibilities:
>>
>>- check /proc/config.gz for CONFIG_KOBJECT_UEVENT
>>   (if /proc/config.gz is available)
>>- use a program to check for it (like the attached one).
> 
> 
> Did you try the program on a kernel without uevents. I think you can
> bind successful to all the 32 netlink sockets even without a "sender".
> 

Great. You are correct.

What now?

Scanning /proc/config.gz is ugly.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke			hare@suse.de
SuSE Linux AG				S390 & zSeries
Maxfeldstraße 5				+49 911 74053 688
90409 Nürnberg				http://www.suse.de


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Re: [PATCH] use uevents in udevd

[Kay Sievers]

On Fri, 2005-01-14 at 14:01 +0100, Hannes Reinecke wrote:
> Kay Sievers wrote:
> > On Fri, 2005-01-14 at 11:55 +0100, Hannes Reinecke wrote:
> > 
> >>Marco d'Itri wrote:
> >>
> >>>On Jan 14, Hannes Reinecke <hare@suse.de> wrote:
> >>>
> >>>
> >>>
> >>>>Comments welcome.
> >>>
> >>>Nice work.
> >>>How can the init scripts determine if support for uevents is available?
> >>>
> >>
> >>Good question. Asked myself the same one just now.
> >>I couldn't figure out whether this information is exported from the 
> >>kernel directly, so that leaves two possibilities:
> >>
> >>- check /proc/config.gz for CONFIG_KOBJECT_UEVENT
> >>   (if /proc/config.gz is available)
> >>- use a program to check for it (like the attached one).
> > 
> > 
> > Did you try the program on a kernel without uevents. I think you can
> > bind successful to all the 32 netlink sockets even without a "sender".
> > 
> 
> Great. You are correct.
> 
> What now?
> 
> Scanning /proc/config.gz is ugly.

We don't need to know that in advance it if we turn the other source of
events off if we get the first add/remove event from netlink. But yes,
we should think about exporting it somewhere.

Kay




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Re: [PATCH] use uevents in udevd

[Arnd Bergmann]

[-- Attachment #1: Type: text/plain, Size: 808 bytes --]

On Freedag 14 Januar 2005 14:12, Kay Sievers wrote:
> On Fri, 2005-01-14 at 14:01 +0100, Arnd Bergmann wrote:
> > On Freedag 14 Januar 2005 12:22, Hannes Reinecke wrote:
> > > Martin promised that z90main will be fixed, so no worries about that 
> > > one. Will have to check pnpbios.
> > 
> > I think z90crypt is clean already, because Z90CRYPT_USE_HOTPLUG is never
> > defined anyway. The option is only there because the source used to be kept
> > in sync with the 2.4 version.
> 
> So how about using the right ifdef's then instead of this obfuscation.

If I were maintaining that file, I'd simply throw out all the dead code.

> And don't you want udev support for that device?

AFAICS, it works fine with udev because it uses a miscdevice now, or am I
missing something?

	Arnd <><

[-- Attachment #2: signature --]
[-- Type: application/pgp-signature, Size: 189 bytes --]

Re: [PATCH] use uevents in udevd

[Kay Sievers]

On Fri, 2005-01-14 at 14:01 +0100, Arnd Bergmann wrote:
> On Freedag 14 Januar 2005 12:22, Hannes Reinecke wrote:
> > Martin promised that z90main will be fixed, so no worries about that 
> > one. Will have to check pnpbios.
> 
> I think z90crypt is clean already, because Z90CRYPT_USE_HOTPLUG is never
> defined anyway. The option is only there because the source used to be kept
> in sync with the 2.4 version.

So how about using the right ifdef's then instead of this obfuscation.
And don't you want udev support for that device?

Thanks,
Kay



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Re: [PATCH] use uevents in udevd

[Hannes Reinecke]

Marco d'Itri wrote:
> On Jan 14, Hannes Reinecke <hare@suse.de> wrote:
> 
> 
>>Well, the main point of the udevd patch is that it's backwards 
>>compatible. So it'll start regardless whether uevent sockets are 
>>available or not.
> 
> But I did understand that you have to start it with -d to use uevents,
> so where is the compatibility?
> 
You only need to start it with '-d' if the udevd is not started by other 
means (eg. udevsend).

udevd will read from netlink sockets if they are available, '-d' doesn't 
affect that.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke			hare@suse.de
SuSE Linux AG				S390 & zSeries
Maxfeldstraße 5				+49 911 74053 688
90409 Nürnberg				http://www.suse.de


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Re: [PATCH] use uevents in udevd

[Kay Sievers]

On Fri, 2005-01-14 at 14:11 +0100, Arnd Bergmann wrote:
> On Freedag 14 Januar 2005 14:12, Kay Sievers wrote:
> > On Fri, 2005-01-14 at 14:01 +0100, Arnd Bergmann wrote:
> > > On Freedag 14 Januar 2005 12:22, Hannes Reinecke wrote:
> > > > Martin promised that z90main will be fixed, so no worries about that 
> > > > one. Will have to check pnpbios.
> > > 
> > > I think z90crypt is clean already, because Z90CRYPT_USE_HOTPLUG is never
> > > defined anyway. The option is only there because the source used to be kept
> > > in sync with the 2.4 version.

So it should not hurt if we make hotplug_path private sometimes after
the input layer is converted. Good to know!

> > So how about using the right ifdef's then instead of this obfuscation.
> 
> If I were maintaining that file, I'd simply throw out all the dead code.

Ah, ok.

> > And don't you want udev support for that device?
> 
> AFAICS, it works fine with udev because it uses a miscdevice now, or am I
> missing something?

Yes, you are right.

Thanks,
Kay



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Re: [PATCH] use uevents in udevd

[Hannes Reinecke]

Kay Sievers wrote:
> On Fri, 2005-01-14 at 12:22 +0100, Hannes Reinecke wrote: 
> 
>>Kay Sievers wrote:
>>
>>>./drivers/input/input.c
>>>./drivers/pnp/pnpbios/core.c
>>>./drivers/s390/crypto/z90main.c
>>>
>>>are still "broken" from that view. They bypass the driver core and don't
>>>send any uevent.
>>>
>>
>>Oh s**t. Still?
>>
>>Time to lean on Vojtech to fix the input layer.
>>Martin promised that z90main will be fixed, so no worries about that 
>>one. Will have to check pnpbios.
> 
Actually, the latest version from -mm already fixes the input layer 
somewhat. At least all input devices have now a proper device and 
driver, although the lower level things (bus devices etc.) are still a 
bit messed up. And the automatic module loading is questionable.

So we have some hope here.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke			hare@suse.de
SuSE Linux AG				S390 & zSeries
Maxfeldstraße 5				+49 911 74053 688
90409 Nürnberg				http://www.suse.de


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Re: [PATCH] use uevents in udevd

[Kay Sievers]

On Fri, 2005-01-14 at 11:22 +0100, Hannes Reinecke wrote:
> this patch adds the capabilities to read uevents directly from the 
> kernel socket (CONFIG_KOBJECT_UEVENT=y).
> The old behaviour is left in place, as with this we can still send 
> events manually.
> 
> And I've added a command-line option '-d' to start udevd as a daemon.
> Now we can do

I've added a simpler version of the -d option along with the separation
of the socket initialization to my tree. I did not add the uevent event
handling, cause we shouldn't do that until the input layer is ready.

Thanks,
Kay



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