Name: Kobject Devpath Sanity Patch
Author: Rusty Russell
Status: Tested in userspace.
Depends: Misc/kobject-style.patch.gz

D: The code to set the DEVPATH environment variable measures it first,
D: kmallocs that amount, copies it in, then sprintfs that into a
D: fixed-length buffer.  Avoid this dance, and copy it straight into
D: the buffer.  Also, put the env. vars on the stack: they're a little
D: large on 64-bit plaforms (256 bytes), but not too bad.  Result is
D: that we only do one kmalloc.

diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .26668-2.5.70-bk18-kobject-sanity.pre/lib/kobject.c .26668-2.5.70-bk18-kobject-sanity/lib/kobject.c
--- .26668-2.5.70-bk18-kobject-sanity.pre/lib/kobject.c	2003-06-14 16:40:22.000000000 +1000
+++ .26668-2.5.70-bk18-kobject-sanity/lib/kobject.c	2003-06-14 16:40:22.000000000 +1000
@@ -66,51 +66,43 @@ static inline struct kobject * to_kobj(s
 
 
 #ifdef CONFIG_HOTPLUG
-static int get_kobj_path_length(struct kset *kset, struct kobject *kobj)
+/* Returns bytes used, including trailing NUL.  Assumes length > 0. */
+static unsigned int fill_kobj_path(struct kobject *kobj,
+				   char *path,
+				   unsigned int length)
 {
-	int length = 1;
-	struct kobject * parent = kobj;
-
-	/* walk up the ancestors until we hit the one pointing to the 
-	 * root.
-	 * Add 1 to strlen for leading '/' of each level.
-	 */
-	do {
-		length += strlen(parent->name) + 1;
-		parent = parent->parent;
-	} while (parent);
-	return length;
-}
+	struct kobject *i;
+	unsigned int used = 0;
 
-static void fill_kobj_path(struct kset *kset, struct kobject *kobj, char *path, int length)
-{
-	struct kobject * parent;
+	/* This is tricky without recursion, since we're going backwards. */
+	for (i = kobj; i; i = i->parent) {
+		/* Too long?  Finish here. */
+		if (used + 1 + strlen(i->name) + 1 > length)
+			break;
 
-	--length;
-	for (parent = kobj; parent; parent = parent->parent) {
-		int cur = strlen(parent->name);
-		/* back up enough to print this name with '/' */
-		length -= cur;
-		strncpy(path + length, parent->name, cur);
-		*(path + --length) = '/';
+		/* Prepend /<name>. */
+		memmove(path + strlen(i->name) + 1, path, used);
+		path[0] = '/';
+		memcpy(path+1, i->name, strlen(i->name));
+		used += 1 + strlen(i->name);
 	}
+	path[used++] = '\0';
 
 	pr_debug("%s: path = '%s'\n",__FUNCTION__,path);
+	return used;
 }
 
 #define BUFFER_SIZE	1024	/* should be enough memory for the env */
 #define NUM_ENVP	32	/* number of env pointers */
+
 static void kset_hotplug(const char *action, struct kset *kset,
 			 struct kobject *kobj)
 {
 	char *argv[3];
-	char **envp = NULL;
+	char *envp[NUM_ENVP] = { 0, };
 	char *buffer = NULL;
-	char *scratch;
-	int i = 0;
+	int i, bufused;
 	int retval;
-	int kobj_path_length;
-	char *kobj_path = NULL;
 	char *name = NULL;
 
 	/* If the kset has a filter operation, call it. If it returns
@@ -125,14 +117,10 @@ static void kset_hotplug(const char *act
 	if (!hotplug_path[0])
 		return;
 
-	envp = kmalloc(NUM_ENVP * sizeof(char *), GFP_KERNEL);
-	if (!envp)
-		return;
-	memset(envp, 0x00, NUM_ENVP * sizeof(char *));
-
 	buffer = kmalloc(BUFFER_SIZE, GFP_KERNEL);
 	if (!buffer)
 		goto exit;
+	bufused = 0;
 
 	if (kset->hotplug_ops->name)
 		name = kset->hotplug_ops->name(kset, kobj);
@@ -144,29 +132,22 @@ static void kset_hotplug(const char *act
 	argv[2] = 0;
 
 	/* minimal command environment */
+	i = 0;
 	envp[i++] = "HOME=/";
 	envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
 
-	scratch = buffer;
-
-	envp[i++] = scratch;
-	scratch += sprintf(scratch, "ACTION=%s", action) + 1;
-
-	kobj_path_length = get_kobj_path_length(kset, kobj);
-	kobj_path = kmalloc(kobj_path_length, GFP_KERNEL);
-	if (!kobj_path)
-		goto exit;
-	memset(kobj_path, 0x00, kobj_path_length);
-	fill_kobj_path(kset, kobj, kobj_path, kobj_path_length);
+	envp[i++] = buffer + bufused;
+	bufused += sprintf(buffer + bufused, "ACTION=%s", action) + 1;
 
-	envp[i++] = scratch;
-	scratch += sprintf(scratch, "DEVPATH=%s", kobj_path) + 1;
+	envp[i++] = buffer + bufused;
+	bufused += sprintf(buffer + bufused, "DEVPATH=");
+	bufused += fill_kobj_path(kobj, buffer + bufused, BUFFER_SIZE-bufused);
 
 	if (kset->hotplug_ops->hotplug) {
 		/* have the kset specific function add its stuff */
 		retval = kset->hotplug_ops->hotplug(kset, kobj,
-				  &envp[i], NUM_ENVP - i, scratch,
-				  BUFFER_SIZE - (scratch - buffer));
+				  &envp[i], NUM_ENVP - i, buffer + bufused,
+				  BUFFER_SIZE - bufused);
 		if (retval) {
 			pr_debug("%s - hotplug() returned %d\n",
 				  __FUNCTION__, retval);
@@ -182,9 +163,7 @@ static void kset_hotplug(const char *act
 			  __FUNCTION__, retval);
 
 exit:
-	kfree(kobj_path);
 	kfree(buffer);
-	kfree(envp);
 	return;
 }
 #else