Re: [adventure] replace /sbin/hotplug by udevd

[Kay Sievers <kay.sievers@vrfy.org>]

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On Thu, Nov 18, 2004 at 11:27:55PM -0800, Greg KH wrote:
> On Fri, Nov 19, 2004 at 02:11:40AM +0100, Kay Sievers wrote:

> > The question is not what we can do _with_ udev for people who don't want
> > udev, right? :)
> 
> Heh, true.
> 
> Ok, I like the idea, it's just going to take a while for me to get used
> to it.  I also need to think about how everyone's going to convert over
> to this new scheme (or not...)

Yeah, it's a good question, how to convert. We need to test it, then we will
get an idea, I expect.

To make the testing easier, here is a version which should by default
behave like the current udev.
Only if /proc/sys/kernel/hotplug is set to call udevsend we switch over to
the new scheme and /etc/hotplug.d is handled from udev.

Thanks,
Kay

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===== dev_d.c 1.20 vs edited =====
--- 1.20/dev_d.c	2004-11-11 22:32:18 +01:00
+++ edited/dev_d.c	2004-11-19 16:00:50 +01:00
@@ -37,6 +37,12 @@ static int run_program(const char *filen
 	int fd;
 	struct udevice *udev = data;
 
+	/* prevent a loop if we handle /etc/hotplug.d */
+	if (strstr(filename, "udev.hotplug") != NULL) {
+		dbg("prevent loop, don't call link pointing to ourself");
+		return 0;
+	}
+
 	dbg("running %s", filename);
 
 	pid = fork();
@@ -96,13 +102,17 @@ void dev_d_execute(struct udevice *udev,
 		temp = strchr(temp, '/');
 	}
 
-	snprintf(dirname, PATH_MAX, "%s/%s", basedir, udev->name);
-	dirname[PATH_MAX-1] = '\0';
-	call_foreach_file(run_program, dirname, suffix, udev);
-
-	snprintf(dirname, PATH_MAX, "%s/%s", basedir, udev->subsystem);
-	dirname[PATH_MAX-1] = '\0';
-	call_foreach_file(run_program, dirname, suffix, udev);
+	if (udev->name[0] != '\0') {
+		snprintf(dirname, PATH_MAX, "%s/%s", basedir, udev->name);
+		dirname[PATH_MAX-1] = '\0';
+		call_foreach_file(run_program, dirname, suffix, udev);
+	}
+
+	if (udev->subsystem[0] != '\0') {
+		snprintf(dirname, PATH_MAX, "%s/%s", basedir, udev->subsystem);
+		dirname[PATH_MAX-1] = '\0';
+		call_foreach_file(run_program, dirname, suffix, udev);
+	}
 
 	snprintf(dirname, PATH_MAX, "%s/default", basedir);
 	dirname[PATH_MAX-1] = '\0';
===== udev.c 1.82 vs edited =====
--- 1.82/udev.c	2004-11-13 06:51:09 +01:00
+++ edited/udev.c	2004-11-19 16:16:40 +01:00
@@ -4,6 +4,7 @@
  * Userspace devfs
  *
  * Copyright (C) 2003,2004 Greg Kroah-Hartman <greg@kroah.com>
+ * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
  *
  *	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
@@ -24,6 +25,7 @@
 #include <stddef.h>
 #include <stdlib.h>
 #include <string.h>
+#include <fcntl.h>
 #include <ctype.h>
 #include <errno.h>
 #include <signal.h>
@@ -68,66 +70,22 @@ int main(int argc, char *argv[], char *e
 {
 	struct sigaction act;
 	struct sysfs_class_device *class_dev;
+	struct sysfs_device *devices_dev;
 	struct udevice udev;
 	char path[SYSFS_PATH_MAX];
+	char helper[256];
+	int fd;
+	int len;
 	int retval = -EINVAL;
-	enum {
-		ADD,
-		REMOVE,
-		UDEVSTART,
-	} act_type;
+	const char *error;
+	const char *action = getenv("ACTION");
+	const char *devpath = getenv("DEVPATH");
+	const char *subsystem = argv[1];
 
 	dbg("version %s", UDEV_VERSION);
 	logging_init("udev");
 	udev_init_config();
 
-	if (strstr(argv[0], "udevstart") || (argv[1] != NULL && strstr(argv[1], "udevstart"))) {
-		act_type = UDEVSTART;
-	} else {
-		const char *action = getenv("ACTION");
-		const char *devpath = getenv("DEVPATH");
-		const char *subsystem = argv[1];
-
-		if (!action) {
-			dbg("no action?");
-			goto exit;
-		}
-		if (strcmp(action, "add") == 0) {
-			act_type = ADD;
-		} else if (strcmp(action, "remove") == 0) {
-			act_type = REMOVE;
-		} else {
-			dbg("no action '%s' for us", action);
-			goto exit;
-		}
-
-		if (!devpath) {
-			dbg("no devpath?");
-			goto exit;
-		}
-		dbg("looking at '%s'", devpath);
-
-		/* we only care about class devices and block stuff */
-		if (!strstr(devpath, "class") && !strstr(devpath, "block")) {
-			dbg("not a block or class device");
-			goto exit;
-		}
-
-		if (!subsystem) {
-			dbg("no subsystem");
-			goto exit;
-		}
-
-		udev_set_values(&udev, devpath, subsystem, action);
-
-		/* skip blacklisted subsystems */
-		if (udev.type != 'n' && subsystem_expect_no_dev(subsystem)) {
-			dbg("don't care about '%s' devices", subsystem);
-			goto exit;
-		};
-
-	}
-
 	/* set signal handlers */
 	act.sa_handler = (void (*) (int))sig_handler;
 	sigemptyset (&act.sa_mask);
@@ -137,51 +95,114 @@ int main(int argc, char *argv[], char *e
 	sigaction(SIGINT, &act, NULL);
 	sigaction(SIGTERM, &act, NULL);
 
-	/* trigger timout to interrupt blocking syscalls */
+	/* trigger timeout to interrupt blocking syscalls */
 	alarm(ALARM_TIMEOUT);
 
-	switch(act_type) {
-	case UDEVSTART:
-		dbg("udevstart");
+	udev_set_values(&udev, devpath, subsystem, action);
+
+	if (strstr(argv[0], "udevstart") || (argv[1] != NULL && strstr(argv[1], "udevstart"))) {
+		dbg("event: udevstart");
 		udev_log = 0;
 		namedev_init();
 		retval = udev_start();
-		break;
-	case ADD:
-		dbg("udev add");
-
-		/* open the device */
-		snprintf(path, SYSFS_PATH_MAX, "%s%s", sysfs_path, udev.devpath);
-		class_dev = sysfs_open_class_device_path(path);
-		if (class_dev == NULL) {
-			dbg ("sysfs_open_class_device_path failed");
-			break;
-		}
-		dbg("opened class_dev->name='%s'", class_dev->name);
+		goto exit;
+	}
 
-		/* init rules */
-		namedev_init();
+	if (!action) {
+		dbg("no action");
+		goto hotplug;
+	}
+
+	if (!subsystem) {
+		dbg("no subsystem");
+		goto hotplug;
+	}
+
+	if (!devpath) {
+		dbg("no devpath");
+		goto hotplug;
+	}
+
+	if ((strncmp(devpath, "/block/", 7) == 0) || (strncmp(devpath, "/class/", 7) == 0)) {
+		if (strcmp(action, "add") == 0) {
+			/* wait for sysfs and possibly add node */
+			dbg("event: udev add");
 
-		/* name, create node, store in db */
-		retval = udev_add_device(&udev, class_dev);
+			/* skip blacklisted subsystems */
+			if (udev.type != 'n' && subsystem_expect_no_dev(udev.subsystem)) {
+				dbg("don't care about '%s' devices", udev.subsystem);
+				goto hotplug;
+			};
+
+			snprintf(path, SYSFS_PATH_MAX, "%s%s", sysfs_path, udev.devpath);
+			class_dev = wait_class_device_open(path);
+			if (class_dev == NULL) {
+				dbg ("sysfs_open_class_device_path failed");
+				goto hotplug;
+			}
+			dbg("opened class_dev->name='%s'", class_dev->name);
+
+			wait_for_class_device(class_dev, &error);
+
+			/* init rules, permissions */
+			namedev_init();
+
+			/* name, create node, store in db */
+			retval = udev_add_device(&udev, class_dev);
+
+			/* run dev.d/ scripts if we created a node or changed a netif name */
+			if (udev.devname[0] != '\0') {
+				setenv("DEVNAME", udev.devname, 1);
+				dev_d_execute(&udev, DEVD_DIR, DEVD_SUFFIX);
+			}
 
-		/* run dev.d/ scripts if we created a node or changed a netif name */
-		if (udev.devname[0] != '\0') {
-			setenv("DEVNAME", udev.devname, 1);
+			sysfs_close_class_device(class_dev);
+		} else if (strcmp(action, "remove") == 0) {
+			/* possibly remove a node */
+			dbg("event: udev remove");
+
+			/* get node from db, delete it */
+			retval = udev_remove_device(&udev);
+
+			/* run scripts */
 			dev_d_execute(&udev, DEVD_DIR, DEVD_SUFFIX);
 		}
+	} else if ((strncmp(devpath, "/devices/", 9) == 0)) {
+		if (strcmp(action, "add") == 0) {
+			/* wait for sysfs */
+			dbg("event: devices add");
 
-		sysfs_close_class_device(class_dev);
-		break;
-	case REMOVE:
-		dbg("udev remove");
+			snprintf(path, SYSFS_PATH_MAX, "%s%s", sysfs_path, devpath);
+			devices_dev = wait_devices_device_open(path);
+			if (!devices_dev) {
+				dbg("error: devices device unavailable (probably remove has beaten us)");
+				goto hotplug;
+			}
+			dbg("devices device opened '%s'", path);
 
-		/* get node from db, delete it*/
-		retval = udev_remove_device(&udev);
+			wait_for_devices_device(devices_dev, &error);
 
-		/* run scripts */
-		dev_d_execute(&udev, DEVD_DIR, DEVD_SUFFIX);
+			sysfs_close_device(devices_dev);
+		} else if (strcmp(action, "remove") == 0) {
+			dbg("event: devices remove");
+		}
+	} else {
+		dbg("event: unhandled");
 	}
+
+hotplug:
+	/* call the hotplug scripts if udevsend is the helper */
+	fd = open("/proc/sys/kernel/hotplug", O_RDONLY);
+	if (fd < 0)
+		goto exit;
+
+	len = read(fd, helper, 256);
+	if (len < 0)
+		goto exit;
+	helper[len] = '\0';
+
+	if (strstr(helper, "udevsend"))
+		dev_d_execute(&udev, HOTPLUGD_DIR, HOTPLUG_SUFFIX);
 
 exit:
 	logging_close();
===== udev.h 1.72 vs edited =====
--- 1.72/udev.h	2004-11-13 06:43:23 +01:00
+++ edited/udev.h	2004-11-19 15:57:18 +01:00
@@ -44,6 +44,9 @@
 #define DEVD_DIR			"/etc/dev.d"
 #define DEVD_SUFFIX			".dev"
 
+#define HOTPLUGD_DIR			"/etc/hotplug.d"
+#define HOTPLUG_SUFFIX			".hotplug"
+
 struct udevice {
 	char devpath[DEVPATH_SIZE];
 	char subsystem[SUBSYSTEM_SIZE];