X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;ds=sidebyside;f=util-linux%2Fmdev.c;h=b1f3d051c7b4927ad8f24e91638891694fca674d;hb=f2b39e088d6ccbf4a540c741059c2f661eebc9ac;hp=73a82314c3cf3ef572ffcdf7b697898c83c2c06f;hpb=0960ca7383b3ef35433c269709d12fa6508cc78a;p=oweals%2Fbusybox.git

diff --git a/util-linux/mdev.c b/util-linux/mdev.c
index 73a82314c..b1f3d051c 100644
--- a/util-linux/mdev.c
+++ b/util-linux/mdev.c
@@ -1,260 +1,542 @@
-/* vi:set ts=4:
+/* vi: set sw=4 ts=4: */
+/*
  *
  * mdev - Mini udev for busybox
  *
  * Copyright 2005 Rob Landley <rob@landley.net>
  * Copyright 2005 Frank Sorenson <frank@tuxrocks.com>
  *
- * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ * Licensed under GPL version 2, see file LICENSE in this tarball for details.
  */
 
-#include <ctype.h>
-#include <dirent.h>
-#include <errno.h>
-#include <fcntl.h>
-#include <stdio.h>
-#include <string.h>
-#include <sys/mman.h>
-#include <sys/stat.h>
-#include <sys/sysmacros.h>
-#include <sys/types.h>
-#include <unistd.h>
-#include <stdlib.h>
-#include "busybox.h"
+#include "libbb.h"
 #include "xregex.h"
 
-#define DEV_PATH	"/dev"
-#define MDEV_CONF	"/etc/mdev.conf"
-
-#include <busybox.h>
-
-struct mdev_globals
-{
+struct globals {
 	int root_major, root_minor;
-} mdev_globals;
+	char *subsystem;
+};
+#define G (*(struct globals*)&bb_common_bufsiz1)
+#define root_major (G.root_major)
+#define root_minor (G.root_minor)
+#define subsystem (G.subsystem)
+
+/* Prevent infinite loops in /sys symlinks */
+#define MAX_SYSFS_DEPTH 3
+
+/* We use additional 64+ bytes in make_device() */
+#define SCRATCH_SIZE 80
+
+#if ENABLE_FEATURE_MDEV_RENAME
+/* Builds an alias path.
+ * This function potentionally reallocates the alias parameter.
+ */
+static char *build_alias(char *alias, const char *device_name)
+{
+	char *dest;
+
+	/* ">bar/": rename to bar/device_name */
+	/* ">bar[/]baz": rename to bar[/]baz */
+	dest = strrchr(alias, '/');
+	if (dest) { /* ">bar/[baz]" ? */
+		*dest = '\0'; /* mkdir bar */
+		bb_make_directory(alias, 0755, FILEUTILS_RECUR);
+		*dest = '/';
+		if (dest[1] == '\0') { /* ">bar/" => ">bar/device_name" */
+			dest = alias;
+			alias = concat_path_file(alias, device_name);
+			free(dest);
+		}
+	}
 
-#define bbg mdev_globals
+	return alias;
+}
+#endif
 
 /* mknod in /dev based on a path like "/sys/block/hda/hda1" */
-static void make_device(char *path)
+/* NB: "mdev -s" may call us many times, do not leak memory/fds! */
+static void make_device(char *path, int delete)
 {
-	char *device_name, *s;
-	int major, minor, type, len, fd;
-	int mode = 0660;
-	uid_t uid = 0;
-	gid_t gid = 0;
-	char *temp = path + strlen(path);
+#if ENABLE_FEATURE_MDEV_CONF
+	parser_t *parser;
+#endif
+	const char *device_name;
+	int major, minor, type, len;
+	int mode;
+	char *dev_maj_min = path + strlen(path);
+
+	/* Force the configuration file settings exactly. */
+	umask(0);
 
 	/* Try to read major/minor string.  Note that the kernel puts \n after
 	 * the data, so we don't need to worry about null terminating the string
-	 * because sscanf() will stop at the first nondigit, which \n is.  We
-	 * also depend on path having writeable space after it. */
-
-	strcat(path, "/dev");
-	fd = open(path, O_RDONLY);
-	len = read(fd, temp + 1, 64);
-	*temp++ = 0;
-	close(fd);
-	if (len < 1) return;
+	 * because sscanf() will stop at the first nondigit, which \n is.
+	 * We also depend on path having writeable space after it.
+	 */
+	major = -1;
+	if (!delete) {
+		strcpy(dev_maj_min, "/dev");
+		len = open_read_close(path, dev_maj_min + 1, 64);
+		*dev_maj_min++ = '\0';
+		if (len < 1) {
+			if (!ENABLE_FEATURE_MDEV_EXEC)
+				return;
+			/* no "dev" file, so just try to run script */
+			*dev_maj_min = '\0';
+		} else if (sscanf(dev_maj_min, "%u:%u", &major, &minor) != 2) {
+			major = -1;
+		}
+	}
 
 	/* Determine device name, type, major and minor */
+	device_name = bb_basename(path);
+	/* http://kernel.org/doc/pending/hotplug.txt says that only
+	 * "/sys/block/..." is for block devices. "/sys/bus" etc is not.
+	 * But since 2.6.25 block devices are also in /sys/class/block.
+	 * We use strstr("/block/") to forestall future surprises. */
+	type = S_IFCHR;
+	if (strstr(path, "/block/"))
+		type = S_IFBLK;
+
+#if ENABLE_FEATURE_MDEV_CONF
+	parser = config_open2("/etc/mdev.conf", fopen_for_read);
+
+	/* If we have config file, look up user settings */
+	while (1) {
+		regmatch_t off[1 + 9*ENABLE_FEATURE_MDEV_RENAME_REGEXP];
+		int keep_matching;
+		char *val;
+		struct bb_uidgid_t ugid;
+		char *tokens[4];
+# if ENABLE_FEATURE_MDEV_EXEC
+		char *command = NULL;
+# endif
+# if ENABLE_FEATURE_MDEV_RENAME
+		char *alias = NULL;
+		char aliaslink = aliaslink; /* for compiler */
+# endif
+		/* Defaults in case we won't match any line */
+		ugid.uid = ugid.gid = 0;
+		keep_matching = 0;
+		mode = 0660;
+
+		if (!config_read(parser, tokens, 4, 3, "# \t", PARSE_NORMAL)) {
+			/* End of file, create dev node with default params */
+			goto line_matches;
+		}
 
-	device_name = strrchr(path, '/') + 1;
-	type = path[5]=='c' ? S_IFCHR : S_IFBLK;
-	if (sscanf(temp, "%d:%d", &major, &minor) != 2) return;
-
-	/* If we have a config file, look up permissions for this device */
-
-	if (ENABLE_FEATURE_MDEV_CONF) {
-		char *conf, *pos, *end;
-
-		/* mmap the config file */
-		if (-1 != (fd=open(MDEV_CONF,O_RDONLY))) {
-			len = lseek(fd, 0, SEEK_END);
-			conf = mmap(NULL, len, PROT_READ, MAP_PRIVATE, fd, 0);
-			if (conf) {
-				int line = 0;
-
-				/* Loop through lines in mmaped file*/
-				for (pos=conf; pos-conf<len;) {
-					int field;
-					char *end2;
-
-					line++;
-					/* find end of this line */
-					for(end=pos; end-conf<len && *end!='\n'; end++)
-						;
-
-					/* Three fields: regex, uid:gid, mode */
-					for (field=3; field; field--) {
-						/* Skip whitespace */
-						while (pos<end && isspace(*pos))
-							pos++;
-						if (pos==end || *pos=='#')
-							break;
-						for (end2=pos; end2<end && !isspace(*end2) && *end2!='#'; end2++)
-							;
-
-						switch (field) {
-							/* Regex to match this device */
-							case 3:
-							{
-								char *regex = strndupa(pos,end2-pos);
-								regex_t match;
-								regmatch_t off;
-								int result;
-
-								/* Is this it? */
-								xregcomp(&match,regex,REG_EXTENDED);
-								result = regexec(&match,device_name,1,&off,0);
-								regfree(&match);
-
-								/* If not this device, skip rest of line */
-								if (result || off.rm_so || off.rm_eo!=strlen(device_name))
-									goto end_line;
-
-								break;
-							}
-							/* uid:gid */
-							case 2:
-							{
-								char *s2;
-
-								/* Find : */
-								for(s=pos; s<end2 && *s!=':'; s++)
-									;
-								if (s == end2)
-									goto end_line;
-
-								/* Parse UID */
-								uid = strtoul(pos,&s2,10);
-								if (s != s2) {
-									struct passwd *pass;
-									pass = getpwnam(strndupa(pos,s-pos));
-									if (!pass)
-										goto end_line;
-									uid = pass->pw_uid;
-								}
-								s++;
-								/* parse GID */
-								gid = strtoul(s,&s2,10);
-								if (end2 != s2) {
-									struct group *grp;
-									grp = getgrnam(strndupa(s,end2-s));
-									if (!grp)
-										goto end_line;
-									gid = grp->gr_gid;
-								}
-								break;
-							}
-							/* mode */
-							case 1:
-							{
-								mode = strtoul(pos,&pos,8);
-								if (pos != end2)
-									goto end_line;
-								else
-									goto found_device;
-							}
-						}
-						pos = end2;
-					}
-end_line:
-					/* Did everything parse happily? */
-					if (field && field!=3)
-						bb_error_msg_and_die("Bad line %d",line);
+		val = tokens[0];
+		keep_matching = ('-' == val[0]);
+		val += keep_matching; /* swallow leading dash */
+
+		/* Fields: regex uid:gid mode [alias] [cmd] */
+
+		/* 1st field: @<numeric maj,min>... */
+		if (val[0] == '@') {
+			/* @major,minor[-last] */
+			/* (useful when name is ambiguous:
+			 * "/sys/class/usb/lp0" and
+			 * "/sys/class/printer/lp0") */
+			int cmaj, cmin0, cmin1, sc;
+			if (major < 0)
+				continue; /* no dev, no match */
+			sc = sscanf(val, "@%u,%u-%u", &cmaj, &cmin0, &cmin1);
+			if (sc < 1 || major != cmaj
+			 || (sc == 2 && minor != cmin0)
+			 || (sc == 3 && (minor < cmin0 || minor > cmin1))
+			) {
+				continue; /* this line doesn't match */
+			}
+		} else { /* ... or regex to match device name */
+			regex_t match;
+			int result;
+			const char *dev_name_or_subsystem = device_name;
+			if ('/' == val[0] && subsystem) {
+				dev_name_or_subsystem = subsystem;
+				val++;
+			}
 
-					/* Next line */
-					pos = ++end;
+			/* Is this it? */
+			xregcomp(&match, val, REG_EXTENDED);
+			result = regexec(&match, dev_name_or_subsystem, ARRAY_SIZE(off), off, 0);
+			regfree(&match);
+
+			//bb_error_msg("matches:");
+			//for (int i = 0; i < ARRAY_SIZE(off); i++) {
+			//	if (off[i].rm_so < 0) continue;
+			//	bb_error_msg("match %d: '%.*s'\n", i,
+			//		(int)(off[i].rm_eo - off[i].rm_so),
+			//		device_name + off[i].rm_so);
+			//}
+
+			/* If not this device, skip rest of line */
+			/* (regexec returns whole pattern as "range" 0) */
+			if (result || off[0].rm_so
+			 || ((int)off[0].rm_eo != (int)strlen(dev_name_or_subsystem))
+			) {
+				continue; /* this line doesn't match */
+			}
+		}
+
+		/* This line matches: stop parsing the file after parsing
+		 * the rest of fields unless keep_matching == 1 */
+
+		/* 2nd field: uid:gid - device ownership */
+		parse_chown_usergroup_or_die(&ugid, tokens[1]);
+
+		/* 3rd field: mode - device permissions */
+		mode = strtoul(tokens[2], NULL, 8);
+
+		val = tokens[3];
+		/* 4th field (opt): >|=alias */
+# if ENABLE_FEATURE_MDEV_RENAME
+		if (!val)
+			goto line_matches;
+		aliaslink = val[0];
+		if (aliaslink == '>' || aliaslink == '=') {
+			char *a, *s, *st;
+#  if ENABLE_FEATURE_MDEV_RENAME_REGEXP
+			char *p;
+			unsigned i, n;
+#  endif
+			a = val;
+			s = strchrnul(val, ' ');
+			st = strchrnul(val, '\t');
+			if (st < s)
+				s = st;
+			val = (s[0] && s[1]) ? s+1 : NULL;
+			s[0] = '\0';
+
+#  if ENABLE_FEATURE_MDEV_RENAME_REGEXP
+			/* substitute %1..9 with off[1..9], if any */
+			n = 0;
+			s = a;
+			while (*s)
+				if (*s++ == '%')
+					n++;
+
+			p = alias = xzalloc(strlen(a) + n * strlen(device_name));
+			s = a + 1;
+			while (*s) {
+				*p = *s;
+				if ('%' == *s) {
+					i = (s[1] - '0');
+					if (i <= 9 && off[i].rm_so >= 0) {
+						n = off[i].rm_eo - off[i].rm_so;
+						strncpy(p, device_name + off[i].rm_so, n);
+						p += n - 1;
+						s++;
+					}
 				}
-found_device:
-				munmap(conf, len);
+				p++;
+				s++;
 			}
-			close(fd);
+#  else
+			alias = xstrdup(a + 1);
+#  endif
+		}
+# endif /* ENABLE_FEATURE_MDEV_RENAME */
+
+# if ENABLE_FEATURE_MDEV_EXEC
+		/* The rest (opt): @|$|*command */
+		if (!val)
+			goto line_matches;
+		{
+			const char *s = "@$*";
+			const char *s2 = strchr(s, val[0]);
+
+			if (!s2)
+				bb_error_msg_and_die("bad line %u", parser->lineno);
+
+			/* Correlate the position in the "@$*" with the delete
+			 * step so that we get the proper behavior:
+			 * @cmd: run on create
+			 * $cmd: run on delete
+			 * *cmd: run on both
+			 */
+			if ((s2 - s + 1) /*1/2/3*/ & /*1/2*/ (1 + delete)) {
+				command = xstrdup(val + 1);
+			}
+		}
+# endif
+		/* End of field parsing */
+ line_matches:
+#endif /* ENABLE_FEATURE_MDEV_CONF */
+
+		/* "Execute" the line we found */
+
+		if (!delete && major >= 0) {
+			if (ENABLE_FEATURE_MDEV_RENAME)
+				unlink(device_name);
+			if (mknod(device_name, mode | type, makedev(major, minor)) && errno != EEXIST)
+				bb_perror_msg_and_die("mknod %s", device_name);
+			if (major == root_major && minor == root_minor)
+				symlink(device_name, "root");
+#if ENABLE_FEATURE_MDEV_CONF
+			chown(device_name, ugid.uid, ugid.gid);
+# if ENABLE_FEATURE_MDEV_RENAME
+			if (alias) {
+				alias = build_alias(alias, device_name);
+				/* move the device, and optionally
+				 * make a symlink to moved device node */
+				if (rename(device_name, alias) == 0 && aliaslink == '>')
+					symlink(alias, device_name);
+				free(alias);
+			}
+# endif
+#endif
+		}
+#if ENABLE_FEATURE_MDEV_EXEC
+		if (command) {
+			/* setenv will leak memory, use putenv/unsetenv/free */
+			char *s = xasprintf("%s=%s", "MDEV", device_name);
+			char *s1 = xasprintf("%s=%s", "SUBSYSTEM", subsystem);
+			putenv(s);
+			putenv(s1);
+			if (system(command) == -1)
+				bb_perror_msg_and_die("can't run '%s'", command);
+			unsetenv("SUBSYSTEM");
+			free(s1);
+			unsetenv("MDEV");
+			free(s);
+			free(command);
+		}
+#endif
+		if (delete) {
+			unlink(device_name);
+			/* At creation time, device might have been moved
+			 * and a symlink might have been created. Undo that. */
+#if ENABLE_FEATURE_MDEV_RENAME
+			if (alias) {
+				alias = build_alias(alias, device_name);
+				unlink(alias);
+				free(alias);
+			}
+#endif
 		}
-	}
 
-	umask(0);
-	if (mknod(device_name, mode | type, makedev(major, minor)) && errno != EEXIST)
-		bb_perror_msg_and_die("mknod %s failed", device_name);
+#if ENABLE_FEATURE_MDEV_CONF
+		/* We found matching line.
+		 * Stop unless it was prefixed with '-' */
+		if (!keep_matching)
+			break;
+	} /* end of "while line is read from /etc/mdev.conf" */
 
-	if (major==bbg.root_major && minor==bbg.root_minor)
-		symlink(device_name, "root");
-	
-	if (ENABLE_FEATURE_MDEV_CONF) chown(device_name, uid, gid);
+	config_close(parser);
+#endif /* ENABLE_FEATURE_MDEV_CONF */
 }
 
-/* Recursive search of /sys/block or /sys/class.  path must be a writeable
- * buffer of size PATH_MAX containing the directory string to start at. */
-
-static void find_dev(char *path)
+/* File callback for /sys/ traversal */
+static int FAST_FUNC fileAction(const char *fileName,
+		struct stat *statbuf UNUSED_PARAM,
+		void *userData,
+		int depth UNUSED_PARAM)
 {
-	DIR *dir;
-	size_t len = strlen(path);
-	struct dirent *entry;
-
-	if ((dir = opendir(path)) == NULL)
-		return;
-
-	while ((entry = readdir(dir)) != NULL) {
-		struct stat st;
-
-		/* Skip "." and ".." (also skips hidden files, which is ok) */
-
-		if (entry->d_name[0] == '.')
-			continue;
+	size_t len = strlen(fileName) - 4; /* can't underflow */
+	char *scratch = userData;
 
-		// uClibc doesn't fill out entry->d_type reliably. so we use lstat().
+	/* len check is for paranoid reasons */
+	if (strcmp(fileName + len, "/dev") != 0 || len >= PATH_MAX)
+		return FALSE;
 
-		snprintf(path+len, PATH_MAX-len, "/%s", entry->d_name);
-		if (!lstat(path, &st) && S_ISDIR(st.st_mode)) find_dev(path);
-		path[len] = 0;
+	strcpy(scratch, fileName);
+	scratch[len] = '\0';
+	make_device(scratch, 0);
 
-		/* If there's a dev entry, mknod it */
+	return TRUE;
+}
 
-		if (!strcmp(entry->d_name, "dev")) make_device(path);
+/* Directory callback for /sys/ traversal */
+static int FAST_FUNC dirAction(const char *fileName UNUSED_PARAM,
+		struct stat *statbuf UNUSED_PARAM,
+		void *userData UNUSED_PARAM,
+		int depth)
+{
+	/* Extract device subsystem -- the name of the directory under /sys/class/ */
+	if (1 == depth) {
+		subsystem = strrchr(fileName, '/');
+		if (subsystem)
+			subsystem++;
 	}
 
-	closedir(dir);
+	return (depth >= MAX_SYSFS_DEPTH ? SKIP : TRUE);
 }
 
-int mdev_main(int argc, char *argv[])
+/* For the full gory details, see linux/Documentation/firmware_class/README
+ *
+ * Firmware loading works like this:
+ * - kernel sets FIRMWARE env var
+ * - userspace checks /lib/firmware/$FIRMWARE
+ * - userspace waits for /sys/$DEVPATH/loading to appear
+ * - userspace writes "1" to /sys/$DEVPATH/loading
+ * - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data
+ * - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading
+ * - kernel loads firmware into device
+ */
+static void load_firmware(const char *const firmware, const char *const sysfs_path)
 {
-	char *action;
-	char *env_path;
-	RESERVE_CONFIG_BUFFER(temp,PATH_MAX);
-
-	bb_xchdir(DEV_PATH);
-
-	/* Scan */
+	int cnt;
+	int firmware_fd, loading_fd, data_fd;
+
+	/* check for /lib/firmware/$FIRMWARE */
+	xchdir("/lib/firmware");
+	firmware_fd = xopen(firmware, O_RDONLY);
+
+	/* in case we goto out ... */
+	data_fd = -1;
+
+	/* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
+	xchdir(sysfs_path);
+	for (cnt = 0; cnt < 30; ++cnt) {
+		loading_fd = open("loading", O_WRONLY);
+		if (loading_fd != -1)
+			goto loading;
+		sleep(1);
+	}
+	goto out;
+
+ loading:
+	/* tell kernel we're loading by `echo 1 > /sys/$DEVPATH/loading` */
+	if (full_write(loading_fd, "1", 1) != 1)
+		goto out;
+
+	/* load firmware by `cat /lib/firmware/$FIRMWARE > /sys/$DEVPATH/data */
+	data_fd = open("data", O_WRONLY);
+	if (data_fd == -1)
+		goto out;
+	cnt = bb_copyfd_eof(firmware_fd, data_fd);
+
+	/* tell kernel result by `echo [0|-1] > /sys/$DEVPATH/loading` */
+	if (cnt > 0)
+		full_write(loading_fd, "0", 1);
+	else
+		full_write(loading_fd, "-1", 2);
+
+ out:
+	if (ENABLE_FEATURE_CLEAN_UP) {
+		close(firmware_fd);
+		close(loading_fd);
+		close(data_fd);
+	}
+}
 
-	if (argc == 2 && !strcmp(argv[1],"-s")) {
+int mdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int mdev_main(int argc UNUSED_PARAM, char **argv)
+{
+	RESERVE_CONFIG_BUFFER(temp, PATH_MAX + SCRATCH_SIZE);
+
+	/* We can be called as hotplug helper */
+	/* Kernel cannot provide suitable stdio fds for us, do it ourself */
+#if 1
+	bb_sanitize_stdio();
+#else
+	/* Debug code */
+	/* Replace LOGFILE by other file or device name if you need */
+#define LOGFILE "/dev/console"
+	/* Just making sure fd 0 is not closed,
+	 * we don't really intend to read from it */
+	xmove_fd(xopen("/", O_RDONLY), STDIN_FILENO);
+	xmove_fd(xopen(LOGFILE, O_WRONLY|O_APPEND), STDOUT_FILENO);
+	xmove_fd(xopen(LOGFILE, O_WRONLY|O_APPEND), STDERR_FILENO);
+#endif
+
+	xchdir("/dev");
+
+	if (argv[1] && strcmp(argv[1], "-s") == 0) {
+		/* Scan:
+		 * mdev -s
+		 */
 		struct stat st;
 
-		stat("/", &st);  // If this fails, we have bigger problems.
-		bbg.root_major=major(st.st_dev);
-		bbg.root_minor=minor(st.st_dev);
-		strcpy(temp,"/sys/block");
-		find_dev(temp);
-		strcpy(temp,"/sys/class");
-		find_dev(temp);
-
-	/* Hotplug */
-
+		xstat("/", &st);
+		root_major = major(st.st_dev);
+		root_minor = minor(st.st_dev);
+
+		/* ACTION_FOLLOWLINKS is needed since in newer kernels
+		 * /sys/block/loop* (for example) are symlinks to dirs,
+		 * not real directories.
+		 * (kernel's CONFIG_SYSFS_DEPRECATED makes them real dirs,
+		 * but we can't enforce that on users)
+		 */
+		if (access("/sys/class/block", F_OK) != 0) {
+			/* Scan obsolete /sys/block only if /sys/class/block
+			 * doesn't exist. Otherwise we'll have dupes.
+			 * Also, do not complain if it doesn't exist.
+			 * Some people configure kernel to have no blockdevs.
+			 */
+			recursive_action("/sys/block",
+				ACTION_RECURSE | ACTION_FOLLOWLINKS | ACTION_QUIET,
+				fileAction, dirAction, temp, 0);
+		}
+		recursive_action("/sys/class",
+			ACTION_RECURSE | ACTION_FOLLOWLINKS,
+			fileAction, dirAction, temp, 0);
 	} else {
+		char *fw;
+		char *seq;
+		char *action;
+		char *env_path;
+
+		/* Hotplug:
+		 * env ACTION=... DEVPATH=... SUBSYSTEM=... [SEQNUM=...] mdev
+		 * ACTION can be "add" or "remove"
+		 * DEVPATH is like "/block/sda" or "/class/input/mice"
+		 */
 		action = getenv("ACTION");
 		env_path = getenv("DEVPATH");
-	    if (!action || !env_path)
+		subsystem = getenv("SUBSYSTEM");
+		if (!action || !env_path /*|| !subsystem*/)
 			bb_show_usage();
+		fw = getenv("FIRMWARE");
+
+		/* If it exists, does /dev/mdev.seq match $SEQNUM?
+		 * If it does not match, earlier mdev is running
+		 * in parallel, and we need to wait */
+		seq = getenv("SEQNUM");
+		if (seq) {
+			int timeout = 2000 / 32; /* 2000 msec */
+			do {
+				int seqlen;
+				char seqbuf[sizeof(int)*3 + 2];
+
+				seqlen = open_read_close("mdev.seq", seqbuf, sizeof(seqbuf-1));
+				if (seqlen < 0) {
+					seq = NULL;
+					break;
+				}
+				seqbuf[seqlen] = '\0';
+				if (seqbuf[0] == '\n' /* seed file? */
+				 || strcmp(seq, seqbuf) == 0 /* correct idx? */
+				) {
+					break;
+				}
+				usleep(32*1000);
+			} while (--timeout);
+		}
 
-		if (!strcmp(action, "add")) {
-			sprintf(temp, "/sys%s", env_path);
-			make_device(temp);
-		} else if (!strcmp(action, "remove")) {
-			unlink(strrchr(env_path, '/') + 1);
+		snprintf(temp, PATH_MAX, "/sys%s", env_path);
+		if (strcmp(action, "remove") == 0) {
+			/* Ignoring "remove firmware". It was reported
+			 * to happen and to cause erroneous deletion
+			 * of device nodes. */
+			if (!fw)
+				make_device(temp, 1);
+		}
+		else if (strcmp(action, "add") == 0) {
+			make_device(temp, 0);
+			if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE) {
+				if (fw)
+					load_firmware(fw, temp);
+			}
+		}
+
+		if (seq) {
+			xopen_xwrite_close("mdev.seq", utoa(xatou(seq) + 1));
 		}
 	}
 
-	if (ENABLE_FEATURE_CLEAN_UP) RELEASE_CONFIG_BUFFER(temp);
-	return 0;
+	if (ENABLE_FEATURE_CLEAN_UP)
+		RELEASE_CONFIG_BUFFER(temp);
+
+	return EXIT_SUCCESS;
 }