12 files changed, 253 insertions, 238 deletions

diff --git a/arch/um/drivers/chan_kern.c b/arch/um/drivers/chan_kern.c
index 7d4190e5565..4e7e3cfa21f 100644
--- a/arch/um/drivers/chan_kern.c
+++ b/arch/um/drivers/chan_kern.c
@@ -19,44 +19,11 @@
 #include "line.h"
 #include "os.h"
 
-/* XXX: could well be moved to somewhere else, if needed. */
-static int my_printf(const char * fmt, ...)
-	__attribute__ ((format (printf, 1, 2)));
-
-static int my_printf(const char * fmt, ...)
-{
-	/* Yes, can be called on atomic context.*/
-	char *buf = kmalloc(4096, GFP_ATOMIC);
-	va_list args;
-	int r;
-
-	if (!buf) {
-		/* We print directly fmt.
-		 * Yes, yes, yes, feel free to complain. */
-		r = strlen(fmt);
-	} else {
-		va_start(args, fmt);
-		r = vsprintf(buf, fmt, args);
-		va_end(args);
-		fmt = buf;
-	}
-
-	if (r)
-		r = os_write_file(1, fmt, r);
-	return r;
-
-}
-
 #ifdef CONFIG_NOCONFIG_CHAN
-/* Despite its name, there's no added trailing newline. */
-static int my_puts(const char * buf)
+static void *not_configged_init(char *str, int device,
+				const struct chan_opts *opts)
 {
-	return os_write_file(1, buf, strlen(buf));
-}
-
-static void *not_configged_init(char *str, int device, struct chan_opts *opts)
-{
-	my_puts("Using a channel type which is configured out of "
+	printk("Using a channel type which is configured out of "
 	       "UML\n");
 	return NULL;
 }
@@ -64,34 +31,34 @@ static void *not_configged_init(char *str, int device, struct chan_opts *opts)
 static int not_configged_open(int input, int output, int primary, void *data,
 			      char **dev_out)
 {
-	my_puts("Using a channel type which is configured out of "
+	printk("Using a channel type which is configured out of "
 	       "UML\n");
 	return -ENODEV;
 }
 
 static void not_configged_close(int fd, void *data)
 {
-	my_puts("Using a channel type which is configured out of "
+	printk("Using a channel type which is configured out of "
 	       "UML\n");
 }
 
 static int not_configged_read(int fd, char *c_out, void *data)
 {
-	my_puts("Using a channel type which is configured out of "
+	printk("Using a channel type which is configured out of "
 	       "UML\n");
 	return -EIO;
 }
 
 static int not_configged_write(int fd, const char *buf, int len, void *data)
 {
-	my_puts("Using a channel type which is configured out of "
+	printk("Using a channel type which is configured out of "
 	       "UML\n");
 	return -EIO;
 }
 
 static int not_configged_console_write(int fd, const char *buf, int len)
 {
-	my_puts("Using a channel type which is configured out of "
+	printk("Using a channel type which is configured out of "
 	       "UML\n");
 	return -EIO;
 }
@@ -99,14 +66,14 @@ static int not_configged_console_write(int fd, const char *buf, int len)
 static int not_configged_window_size(int fd, void *data, unsigned short *rows,
 				     unsigned short *cols)
 {
-	my_puts("Using a channel type which is configured out of "
+	printk("Using a channel type which is configured out of "
 	       "UML\n");
 	return -ENODEV;
 }
 
 static void not_configged_free(void *data)
 {
-	my_puts("Using a channel type which is configured out of "
+	printk("Using a channel type which is configured out of "
 	       "UML\n");
 }
 
@@ -534,7 +501,7 @@ static const struct chan_type chan_table[] = {
 };
 
 static struct chan *parse_chan(struct line *line, char *str, int device,
-			       const struct chan_opts *opts)
+			       const struct chan_opts *opts, char **error_out)
 {
 	const struct chan_type *entry;
 	const struct chan_ops *ops;
@@ -553,19 +520,21 @@ static struct chan *parse_chan(struct line *line, char *str, int device,
 		}
 	}
 	if(ops == NULL){
-		my_printf("parse_chan couldn't parse \"%s\"\n",
-		       str);
+		*error_out = "No match for configured backends";
 		return NULL;
 	}
-	if(ops->init == NULL)
-		return NULL;
+
 	data = (*ops->init)(str, device, opts);
-	if(data == NULL)
+	if(data == NULL){
+		*error_out = "Configuration failed";
 		return NULL;
+	}
 
 	chan = kmalloc(sizeof(*chan), GFP_ATOMIC);
-	if(chan == NULL)
+	if(chan == NULL){
+		*error_out = "Memory allocation failed";
 		return NULL;
+	}
 	*chan = ((struct chan) { .list	 	= LIST_HEAD_INIT(chan->list),
 				 .free_list 	=
 				 	LIST_HEAD_INIT(chan->free_list),
@@ -582,7 +551,7 @@ static struct chan *parse_chan(struct line *line, char *str, int device,
 }
 
 int parse_chan_pair(char *str, struct line *line, int device,
-		    const struct chan_opts *opts)
+		    const struct chan_opts *opts, char **error_out)
 {
 	struct list_head *chans = &line->chan_list;
 	struct chan *new, *chan;
@@ -599,14 +568,14 @@ int parse_chan_pair(char *str, struct line *line, int device,
 		in = str;
 		*out = '\0';
 		out++;
-		new = parse_chan(line, in, device, opts);
+		new = parse_chan(line, in, device, opts, error_out);
 		if(new == NULL)
 			return -1;
 
 		new->input = 1;
 		list_add(&new->list, chans);
 
-		new = parse_chan(line, out, device, opts);
+		new = parse_chan(line, out, device, opts, error_out);
 		if(new == NULL)
 			return -1;
 
@@ -614,7 +583,7 @@ int parse_chan_pair(char *str, struct line *line, int device,
 		new->output = 1;
 	}
 	else {
-		new = parse_chan(line, str, device, opts);
+		new = parse_chan(line, str, device, opts, error_out);
 		if(new == NULL)
 			return -1;
 
diff --git a/arch/um/drivers/line.c b/arch/um/drivers/line.c
index 799fca3644e..e620ed46ed3 100644
--- a/arch/um/drivers/line.c
+++ b/arch/um/drivers/line.c
@@ -549,14 +549,16 @@ void close_lines(struct line *lines, int nlines)
 		close_chan(&lines[i].chan_list, 0);
 }
 
-static void setup_one_line(struct line *lines, int n, char *init, int init_prio)
+static int setup_one_line(struct line *lines, int n, char *init, int init_prio,
+			  char **error_out)
 {
 	struct line *line = &lines[n];
+	int err = -EINVAL;
 
 	spin_lock(&line->count_lock);
 
 	if(line->tty != NULL){
-		printk("line_setup - device %d is open\n", n);
+		*error_out = "Device is already open";
 		goto out;
 	}
 
@@ -569,18 +571,22 @@ static void setup_one_line(struct line *lines, int n, char *init, int init_prio)
 			line->valid = 1;
 		}
 	}
+	err = 0;
 out:
 	spin_unlock(&line->count_lock);
+	return err;
 }
 
 /* Common setup code for both startup command line and mconsole initialization.
  * @lines contains the array (of size @num) to modify;
  * @init is the setup string;
+ * @error_out is an error string in the case of failure;
  */
 
-int line_setup(struct line *lines, unsigned int num, char *init)
+int line_setup(struct line *lines, unsigned int num, char *init,
+	       char **error_out)
 {
-	int i, n;
+	int i, n, err;
 	char *end;
 
 	if(*init == '=') {
@@ -591,52 +597,56 @@ int line_setup(struct line *lines, unsigned int num, char *init)
 	else {
 		n = simple_strtoul(init, &end, 0);
 		if(*end != '='){
-			printk(KERN_ERR "line_setup failed to parse \"%s\"\n",
-			       init);
-			return 0;
+			*error_out = "Couldn't parse device number";
+			return -EINVAL;
 		}
 		init = end;
 	}
 	init++;
 
 	if (n >= (signed int) num) {
-		printk("line_setup - %d out of range ((0 ... %d) allowed)\n",
-		       n, num - 1);
-		return 0;
+		*error_out = "Device number out of range";
+		return -EINVAL;
+	}
+	else if (n >= 0){
+		err = setup_one_line(lines, n, init, INIT_ONE, error_out);
+		if(err)
+			return err;
 	}
-	else if (n >= 0)
-		setup_one_line(lines, n, init, INIT_ONE);
 	else {
-		for(i = 0; i < num; i++)
-			setup_one_line(lines, i, init, INIT_ALL);
+		for(i = 0; i < num; i++){
+			err = setup_one_line(lines, i, init, INIT_ALL,
+					     error_out);
+			if(err)
+				return err;
+		}
 	}
 	return n == -1 ? num : n;
 }
 
 int line_config(struct line *lines, unsigned int num, char *str,
-		const struct chan_opts *opts)
+		const struct chan_opts *opts, char **error_out)
 {
 	struct line *line;
 	char *new;
 	int n;
 
 	if(*str == '='){
-		printk("line_config - can't configure all devices from "
-		       "mconsole\n");
-		return 1;
+		*error_out = "Can't configure all devices from mconsole";
+		return -EINVAL;
 	}
 
 	new = kstrdup(str, GFP_KERNEL);
 	if(new == NULL){
-		printk("line_config - kstrdup failed\n");
-		return 1;
+		*error_out = "Failed to allocate memory";
+		return -ENOMEM;
 	}
-	n = line_setup(lines, num, new);
+	n = line_setup(lines, num, new, error_out);
 	if(n < 0)
-		return 1;
+		return n;
 
 	line = &lines[n];
-	return parse_chan_pair(line->init_str, line, n, opts);
+	return parse_chan_pair(line->init_str, line, n, opts, error_out);
 }
 
 int line_get_config(char *name, struct line *lines, unsigned int num, char *str,
@@ -685,13 +695,13 @@ int line_id(char **str, int *start_out, int *end_out)
         return n;
 }
 
-int line_remove(struct line *lines, unsigned int num, int n)
+int line_remove(struct line *lines, unsigned int num, int n, char **error_out)
 {
 	int err;
 	char config[sizeof("conxxxx=none\0")];
 
 	sprintf(config, "%d=none", n);
-	err = line_setup(lines, num, config);
+	err = line_setup(lines, num, config, error_out);
 	if(err >= 0)
 		err = 0;
 	return err;
@@ -740,6 +750,7 @@ static LIST_HEAD(winch_handlers);
 void lines_init(struct line *lines, int nlines, struct chan_opts *opts)
 {
 	struct line *line;
+	char *error;
 	int i;
 
 	for(i = 0; i < nlines; i++){
@@ -754,8 +765,9 @@ void lines_init(struct line *lines, int nlines, struct chan_opts *opts)
 		if(line->init_str == NULL)
 			printk("lines_init - kstrdup returned NULL\n");
 
-		if(parse_chan_pair(line->init_str, line, i, opts)){
-			printk("parse_chan_pair failed for device %d\n", i);
+		if(parse_chan_pair(line->init_str, line, i, opts, &error)){
+			printk("parse_chan_pair failed for device %d : %s\n",
+			       i, error);
 			line->valid = 0;
 		}
 	}
diff --git a/arch/um/drivers/mconsole_kern.c b/arch/um/drivers/mconsole_kern.c
index 96f0189327a..832d5c766ca 100644
--- a/arch/um/drivers/mconsole_kern.c
+++ b/arch/um/drivers/mconsole_kern.c
@@ -371,14 +371,16 @@ static unsigned long long unplugged_pages_count = 0;
 static struct list_head unplugged_pages = LIST_HEAD_INIT(unplugged_pages);
 static int unplug_index = UNPLUGGED_PER_PAGE;
 
-static int mem_config(char *str)
+static int mem_config(char *str, char **error_out)
 {
 	unsigned long long diff;
 	int err = -EINVAL, i, add;
 	char *ret;
 
-	if(str[0] != '=')
+	if(str[0] != '='){
+		*error_out = "Expected '=' after 'mem'";
 		goto out;
+	}
 
 	str++;
 	if(str[0] == '-')
@@ -386,12 +388,17 @@ static int mem_config(char *str)
 	else if(str[0] == '+'){
 		add = 1;
 	}
-	else goto out;
+	else {
+		*error_out = "Expected increment to start with '-' or '+'";
+		goto out;
+	}
 
 	str++;
 	diff = memparse(str, &ret);
-	if(*ret != '\0')
+	if(*ret != '\0'){
+		*error_out = "Failed to parse memory increment";
 		goto out;
+	}
 
 	diff /= PAGE_SIZE;
 
@@ -435,11 +442,14 @@ static int mem_config(char *str)
 				unplugged = list_entry(entry,
 						       struct unplugged_pages,
 						       list);
-				unplugged->pages[unplug_index++] = addr;
 				err = os_drop_memory(addr, PAGE_SIZE);
-				if(err)
+				if(err){
 					printk("Failed to release memory - "
 					       "errno = %d\n", err);
+					*error_out = "Failed to release memory";
+					goto out;
+				}
+				unplugged->pages[unplug_index++] = addr;
 			}
 
 			unplugged_pages_count++;
@@ -470,8 +480,9 @@ static int mem_id(char **str, int *start_out, int *end_out)
 	return 0;
 }
 
-static int mem_remove(int n)
+static int mem_remove(int n, char **error_out)
 {
+	*error_out = "Memory doesn't support the remove operation";
 	return -EBUSY;
 }
 
@@ -542,7 +553,7 @@ static void mconsole_get_config(int (*get_config)(char *, char *, int,
 void mconsole_config(struct mc_request *req)
 {
 	struct mc_device *dev;
-	char *ptr = req->request.data, *name;
+	char *ptr = req->request.data, *name, *error_string = "";
 	int err;
 
 	ptr += strlen("config");
@@ -559,8 +570,8 @@ void mconsole_config(struct mc_request *req)
 		ptr++;
 
 	if(*ptr == '='){
-		err = (*dev->config)(name);
-		mconsole_reply(req, "", err, 0);
+		err = (*dev->config)(name, &error_string);
+		mconsole_reply(req, error_string, err, 0);
 	}
 	else mconsole_get_config(dev->get_config, req, name);
 }
@@ -595,13 +606,16 @@ void mconsole_remove(struct mc_request *req)
 		goto out;
 	}
 
-	err = (*dev->remove)(n);
+	err_msg = NULL;
+	err = (*dev->remove)(n, &err_msg);
 	switch(err){
 	case -ENODEV:
-		err_msg = "Device doesn't exist";
+		if(err_msg == NULL)
+			err_msg = "Device doesn't exist";
 		break;
 	case -EBUSY:
-		err_msg = "Device is currently open";
+		if(err_msg == NULL)
+			err_msg = "Device is currently open";
 		break;
 	default:
 		break;
diff --git a/arch/um/drivers/net_kern.c b/arch/um/drivers/net_kern.c
index afe3d427ddf..07e839e387d 100644
--- a/arch/um/drivers/net_kern.c
+++ b/arch/um/drivers/net_kern.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org) and 
+ * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org) and
  * James Leu (jleu@mindspring.net).
  * Copyright (C) 2001 by various other people who didn't put their name here.
  * Licensed under the GPL.
@@ -91,8 +91,8 @@ irqreturn_t uml_net_interrupt(int irq, void *dev_id)
 	spin_lock(&lp->lock);
 	while((err = uml_net_rx(dev)) > 0) ;
 	if(err < 0) {
-		printk(KERN_ERR 
-		       "Device '%s' read returned %d, shutting it down\n", 
+		printk(KERN_ERR
+		       "Device '%s' read returned %d, shutting it down\n",
 		       dev->name, err);
 		/* dev_close can't be called in interrupt context, and takes
 		 * again lp->lock.
@@ -159,7 +159,7 @@ out:
 static int uml_net_close(struct net_device *dev)
 {
 	struct uml_net_private *lp = dev->priv;
-	
+
 	netif_stop_queue(dev);
 
 	free_irq(dev->irq, dev);
@@ -194,7 +194,7 @@ static int uml_net_start_xmit(struct sk_buff *skb, struct net_device *dev)
 
 		/* this is normally done in the interrupt when tx finishes */
 		netif_wake_queue(dev);
-	} 
+	}
 	else if(len == 0){
 		netif_start_queue(dev);
 		lp->stats.tx_dropped++;
@@ -333,7 +333,7 @@ static int eth_configure(int n, void *init, char *mac,
 	struct uml_net_private *lp;
 	int save, err, size;
 
-	size = transport->private_size + sizeof(struct uml_net_private) + 
+	size = transport->private_size + sizeof(struct uml_net_private) +
 		sizeof(((struct uml_net_private *) 0)->user);
 
 	device = kzalloc(sizeof(*device), GFP_KERNEL);
@@ -438,7 +438,7 @@ static int eth_configure(int n, void *init, char *mac,
 	lp->tl.function = uml_net_user_timer_expire;
 	memcpy(lp->mac, device->mac, sizeof(lp->mac));
 
-	if (transport->user->init) 
+	if (transport->user->init)
 		(*transport->user->init)(&lp->user, dev);
 
 	set_ether_mac(dev, device->mac);
@@ -463,35 +463,33 @@ static struct uml_net *find_device(int n)
 	return(device);
 }
 
-static int eth_parse(char *str, int *index_out, char **str_out)
+static int eth_parse(char *str, int *index_out, char **str_out,
+		     char **error_out)
 {
 	char *end;
-	int n;
+	int n, err = -EINVAL;;
 
 	n = simple_strtoul(str, &end, 0);
 	if(end == str){
-		printk(KERN_ERR "eth_setup: Failed to parse '%s'\n", str);
-		return(1);
-	}
-	if(n < 0){
-		printk(KERN_ERR "eth_setup: device %d is negative\n", n);
-		return(1);
+		*error_out = "Bad device number";
+		return err;
 	}
+
 	str = end;
 	if(*str != '='){
-		printk(KERN_ERR 
-		       "eth_setup: expected '=' after device number\n");
-		return(1);
+		*error_out = "Expected '=' after device number";
+		return err;
 	}
+
 	str++;
 	if(find_device(n)){
-		printk(KERN_ERR "eth_setup: Device %d already configured\n",
-		       n);
-		return(1);
+		*error_out = "Device already configured";
+		return err;
 	}
-	if(index_out) *index_out = n;
+
+	*index_out = n;
 	*str_out = str;
-	return(0);
+	return 0;
 }
 
 struct eth_init {
@@ -581,11 +579,15 @@ static int eth_setup_common(char *str, int index)
 static int eth_setup(char *str)
 {
 	struct eth_init *new;
+	char *error;
 	int n, err;
 
-	err = eth_parse(str, &n, &str);
-	if(err)
+	err = eth_parse(str, &n, &str, &error);
+	if(err){
+		printk(KERN_ERR "eth_setup - Couldn't parse '%s' : %s\n",
+		       str, error);
 		return 1;
+	}
 
 	new = alloc_bootmem(sizeof(*new));
 	if (new == NULL){
@@ -619,26 +621,30 @@ static int eth_init(void)
 		if(eth_setup_common(eth->init, eth->index))
 			list_del(&eth->list);
 	}
-	
+
 	return(1);
 }
 __initcall(eth_init);
 #endif
 
-static int net_config(char *str)
+static int net_config(char *str, char **error_out)
 {
 	int n, err;
 
-	err = eth_parse(str, &n, &str);
-	if(err) return(err);
+	err = eth_parse(str, &n, &str, error_out);
+	if(err)
+		return err;
 
+	/* This string is broken up and the pieces used by the underlying
+	 * driver.  So, it is freed only if eth_setup_common fails.
+	 */
 	str = kstrdup(str, GFP_KERNEL);
 	if(str == NULL){
-		printk(KERN_ERR "net_config failed to strdup string\n");
-		return(-1);
+	        *error_out = "net_config failed to strdup string";
+		return -ENOMEM;
 	}
 	err = !eth_setup_common(str, n);
-	if(err) 
+	if(err)
 		kfree(str);
 	return(err);
 }
@@ -658,7 +664,7 @@ static int net_id(char **str, int *start_out, int *end_out)
         return n;
 }
 
-static int net_remove(int n)
+static int net_remove(int n, char **error_out)
 {
 	struct uml_net *device;
 	struct net_device *dev;
@@ -727,7 +733,7 @@ struct notifier_block uml_inetaddr_notifier = {
 static int uml_net_init(void)
 {
 	struct list_head *ele;
-	struct uml_net_private *lp;	
+	struct uml_net_private *lp;
 	struct in_device *ip;
 	struct in_ifaddr *in;
 
@@ -747,7 +753,7 @@ static int uml_net_init(void)
 			uml_inetaddr_event(NULL, NETDEV_UP, in);
 			in = in->ifa_next;
 		}
-	}	
+	}
 
 	return(0);
 }
@@ -783,8 +789,8 @@ struct sk_buff *ether_adjust_skb(struct sk_buff *skb, int extra)
 	return(skb);
 }
 
-void iter_addresses(void *d, void (*cb)(unsigned char *, unsigned char *, 
-					void *), 
+void iter_addresses(void *d, void (*cb)(unsigned char *, unsigned char *,
+					void *),
 		    void *arg)
 {
 	struct net_device *dev = d;
@@ -809,11 +815,11 @@ int dev_netmask(void *d, void *m)
 	struct in_ifaddr *in;
 	__be32 *mask_out = m;
 
-	if(ip == NULL) 
+	if(ip == NULL)
 		return(1);
 
 	in = ip->ifa_list;
-	if(in == NULL) 
+	if(in == NULL)
 		return(1);
 
 	*mask_out = in->ifa_mask;
@@ -835,7 +841,7 @@ void free_output_buffer(void *buffer)
 	free_pages((unsigned long) buffer, 0);
 }
 
-int tap_setup_common(char *str, char *type, char **dev_name, char **mac_out, 
+int tap_setup_common(char *str, char *type, char **dev_name, char **mac_out,
 		     char **gate_addr)
 {
 	char *remain;
@@ -854,14 +860,3 @@ unsigned short eth_protocol(struct sk_buff *skb)
 {
 	return(eth_type_trans(skb, skb->dev));
 }
-
-/*
- * Overrides for Emacs so that we follow Linus's tabbing style.
- * Emacs will notice this stuff at the end of the file and automatically
- * adjust the settings for this buffer only.  This must remain at the end
- * of the file.
- * ---------------------------------------------------------------------------
- * Local variables:
- * c-file-style: "linux"
- * End:
- */
diff --git a/arch/um/drivers/ssl.c b/arch/um/drivers/ssl.c
index ed9c59082d0..1e82430b844 100644
--- a/arch/um/drivers/ssl.c
+++ b/arch/um/drivers/ssl.c
@@ -46,9 +46,9 @@ static struct chan_opts opts = {
 	.in_kernel 	= 1,
 };
 
-static int ssl_config(char *str);
+static int ssl_config(char *str, char **error_out);
 static int ssl_get_config(char *dev, char *str, int size, char **error_out);
-static int ssl_remove(int n);
+static int ssl_remove(int n, char **error_out);
 
 static struct line_driver driver = {
 	.name 			= "UML serial line",
@@ -80,9 +80,10 @@ static struct line serial_lines[NR_PORTS] =
 
 static struct lines lines = LINES_INIT(NR_PORTS);
 
-static int ssl_config(char *str)
+static int ssl_config(char *str, char **error_out)
 {
-	return line_config(serial_lines, ARRAY_SIZE(serial_lines), str, &opts);
+	return line_config(serial_lines, ARRAY_SIZE(serial_lines), str, &opts,
+			   error_out);
 }
 
 static int ssl_get_config(char *dev, char *str, int size, char **error_out)
@@ -91,9 +92,10 @@ static int ssl_get_config(char *dev, char *str, int size, char **error_out)
 			       size, error_out);
 }
 
-static int ssl_remove(int n)
+static int ssl_remove(int n, char **error_out)
 {
-	return line_remove(serial_lines, ARRAY_SIZE(serial_lines), n);
+	return line_remove(serial_lines, ARRAY_SIZE(serial_lines), n,
+			   error_out);
 }
 
 static int ssl_open(struct tty_struct *tty, struct file *filp)
@@ -212,7 +214,15 @@ __uml_exitcall(ssl_exit);
 
 static int ssl_chan_setup(char *str)
 {
-	return line_setup(serial_lines, ARRAY_SIZE(serial_lines), str);
+	char *error;
+	int ret;
+
+	ret = line_setup(serial_lines, ARRAY_SIZE(serial_lines), str, &error);
+	if(ret < 0)
+		printk(KERN_ERR "Failed to set up serial line with "
+		       "configuration string \"%s\" : %s\n", str, error);
+
+	return 1;
 }
 
 __setup("ssl", ssl_chan_setup);
diff --git a/arch/um/drivers/stdio_console.c b/arch/um/drivers/stdio_console.c
index 9b2dd0b8a43..3cbfe3a8860 100644
--- a/arch/um/drivers/stdio_console.c
+++ b/arch/um/drivers/stdio_console.c
@@ -52,9 +52,9 @@ static struct chan_opts opts = {
 	.in_kernel 	= 1,
 };
 
-static int con_config(char *str);
+static int con_config(char *str, char **error_out);
 static int con_get_config(char *dev, char *str, int size, char **error_out);
-static int con_remove(int n);
+static int con_remove(int n, char **con_remove);
 
 static struct line_driver driver = {
 	.name 			= "UML console",
@@ -87,9 +87,9 @@ static struct line vts[MAX_TTYS] = { LINE_INIT(CONFIG_CON_ZERO_CHAN, &driver),
 				     [ 1 ... MAX_TTYS - 1 ] =
 				     LINE_INIT(CONFIG_CON_CHAN, &driver) };
 
-static int con_config(char *str)
+static int con_config(char *str, char **error_out)
 {
-	return line_config(vts, ARRAY_SIZE(vts), str, &opts);
+	return line_config(vts, ARRAY_SIZE(vts), str, &opts, error_out);
 }
 
 static int con_get_config(char *dev, char *str, int size, char **error_out)
@@ -97,9 +97,9 @@ static int con_get_config(char *dev, char *str, int size, char **error_out)
 	return line_get_config(dev, vts, ARRAY_SIZE(vts), str, size, error_out);
 }
 
-static int con_remove(int n)
+static int con_remove(int n, char **error_out)
 {
-	return line_remove(vts, ARRAY_SIZE(vts), n);
+	return line_remove(vts, ARRAY_SIZE(vts), n, error_out);
 }
 
 static int con_open(struct tty_struct *tty, struct file *filp)
@@ -192,7 +192,15 @@ __uml_exitcall(console_exit);
 
 static int console_chan_setup(char *str)
 {
-	return line_setup(vts, ARRAY_SIZE(vts), str);
+	char *error;
+	int ret;
+
+	ret = line_setup(vts, ARRAY_SIZE(vts), str, &error);
+	if(ret < 0)
+		printk(KERN_ERR "Failed to set up console with "
+		       "configuration string \"%s\" : %s\n", str, error);
+
+	return 1;
 }
 __setup("con", console_chan_setup);
 __channel_help(console_chan_setup, "con");
diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
index 49c047b75cc..f4db97efc01 100644
--- a/arch/um/drivers/ubd_kern.c
+++ b/arch/um/drivers/ubd_kern.c
@@ -286,7 +286,7 @@ static int parse_unit(char **ptr)
  * otherwise, the str pointer is used (and owned) inside ubd_devs array, so it
  * should not be freed on exit.
  */
-static int ubd_setup_common(char *str, int *index_out)
+static int ubd_setup_common(char *str, int *index_out, char **error_out)
 {
 	struct ubd *ubd_dev;
 	struct openflags flags = global_openflags;
@@ -302,56 +302,54 @@ static int ubd_setup_common(char *str, int *index_out)
 		str++;
 		if(!strcmp(str, "sync")){
 			global_openflags = of_sync(global_openflags);
-			return(0);
+			return 0;
 		}
 		major = simple_strtoul(str, &end, 0);
 		if((*end != '\0') || (end == str)){
-			printk(KERN_ERR
-			       "ubd_setup : didn't parse major number\n");
-			return(1);
+			*error_out = "Didn't parse major number";
+			return -EINVAL;
 		}
 
-		err = 1;
- 		mutex_lock(&ubd_lock);
- 		if(fake_major != MAJOR_NR){
- 			printk(KERN_ERR "Can't assign a fake major twice\n");
- 			goto out1;
- 		}
+		err = -EINVAL;
+		mutex_lock(&ubd_lock);
+		if(fake_major != MAJOR_NR){
+			*error_out = "Can't assign a fake major twice";
+			goto out1;
+		}
 
- 		fake_major = major;
+		fake_major = major;
 
 		printk(KERN_INFO "Setting extra ubd major number to %d\n",
 		       major);
- 		err = 0;
- 	out1:
- 		mutex_unlock(&ubd_lock);
-		return(err);
+		err = 0;
+	out1:
+		mutex_unlock(&ubd_lock);
+		return err;
 	}
 
 	n = parse_unit(&str);
 	if(n < 0){
-		printk(KERN_ERR "ubd_setup : couldn't parse unit number "
-		       "'%s'\n", str);
-		return(1);
+		*error_out = "Couldn't parse device number";
+		return -EINVAL;
 	}
 	if(n >= MAX_DEV){
-		printk(KERN_ERR "ubd_setup : index %d out of range "
-		       "(%d devices, from 0 to %d)\n", n, MAX_DEV, MAX_DEV - 1);
-		return(1);
+		*error_out = "Device number out of range";
+		return 1;
 	}
 
-	err = 1;
+	err = -EBUSY;
 	mutex_lock(&ubd_lock);
 
 	ubd_dev = &ubd_devs[n];
 	if(ubd_dev->file != NULL){
-		printk(KERN_ERR "ubd_setup : device already configured\n");
+		*error_out = "Device is already configured";
 		goto out;
 	}
 
 	if (index_out)
 		*index_out = n;
 
+	err = -EINVAL;
 	for (i = 0; i < sizeof("rscd="); i++) {
 		switch (*str) {
 		case 'r':
@@ -370,47 +368,54 @@ static int ubd_setup_common(char *str, int *index_out)
 			str++;
 			goto break_loop;
 		default:
-			printk(KERN_ERR "ubd_setup : Expected '=' or flag letter (r, s, c, or d)\n");
+			*error_out = "Expected '=' or flag letter "
+				"(r, s, c, or d)";
 			goto out;
 		}
 		str++;
 	}
 
-        if (*str == '=')
-		printk(KERN_ERR "ubd_setup : Too many flags specified\n");
-        else
-		printk(KERN_ERR "ubd_setup : Expected '='\n");
+	if (*str == '=')
+		*error_out = "Too many flags specified";
+	else
+		*error_out = "Missing '='";
 	goto out;
 
 break_loop:
-	err = 0;
 	backing_file = strchr(str, ',');
 
-	if (!backing_file) {
+	if (backing_file == NULL)
 		backing_file = strchr(str, ':');
-	}
 
-	if(backing_file){
-		if(ubd_dev->no_cow)
-			printk(KERN_ERR "Can't specify both 'd' and a "
-			       "cow file\n");
+	if(backing_file != NULL){
+		if(ubd_dev->no_cow){
+			*error_out = "Can't specify both 'd' and a cow file";
+			goto out;
+		}
 		else {
 			*backing_file = '\0';
 			backing_file++;
 		}
 	}
+	err = 0;
 	ubd_dev->file = str;
 	ubd_dev->cow.file = backing_file;
 	ubd_dev->boot_openflags = flags;
 out:
 	mutex_unlock(&ubd_lock);
-	return(err);
+	return err;
 }
 
 static int ubd_setup(char *str)
 {
-	ubd_setup_common(str, NULL);
-	return(1);
+	char *error;
+	int err;
+
+	err = ubd_setup_common(str, NULL, &error);
+	if(err)
+		printk(KERN_ERR "Failed to initialize device with \"%s\" : "
+		       "%s\n", str, error);
+	return 1;
 }
 
 __setup("ubd", ubd_setup);
@@ -422,7 +427,7 @@ __uml_help(ubd_setup,
 "    use either a ':' or a ',': the first one allows writing things like;\n"
 "	ubd0=~/Uml/root_cow:~/Uml/root_backing_file\n"
 "    while with a ',' the shell would not expand the 2nd '~'.\n"
-"    When using only one filename, UML will detect whether to thread it like\n"
+"    When using only one filename, UML will detect whether to treat it like\n"
 "    a COW file or a backing file. To override this detection, add the 'd'\n"
 "    flag:\n"
 "	ubd0d=BackingFile\n"
@@ -668,18 +673,19 @@ static int ubd_disk_register(int major, u64 size, int unit,
 
 #define ROUND_BLOCK(n) ((n + ((1 << 9) - 1)) & (-1 << 9))
 
-static int ubd_add(int n)
+static int ubd_add(int n, char **error_out)
 {
 	struct ubd *ubd_dev = &ubd_devs[n];
-	int err;
+	int err = 0;
 
-	err = -ENODEV;
 	if(ubd_dev->file == NULL)
 		goto out;
 
 	err = ubd_file_size(ubd_dev, &ubd_dev->size);
-	if(err < 0)
+	if(err < 0){
+		*error_out = "Couldn't determine size of device's file";
 		goto out;
+	}
 
 	ubd_dev->size = ROUND_BLOCK(ubd_dev->size);
 
@@ -701,28 +707,31 @@ out:
 	return err;
 }
 
-static int ubd_config(char *str)
+static int ubd_config(char *str, char **error_out)
 {
 	int n, ret;
 
+	/* This string is possibly broken up and stored, so it's only
+	 * freed if ubd_setup_common fails, or if only general options
+	 * were set.
+	 */
 	str = kstrdup(str, GFP_KERNEL);
 	if (str == NULL) {
-		printk(KERN_ERR "ubd_config failed to strdup string\n");
-		ret = 1;
-		goto out;
+		*error_out = "Failed to allocate memory";
+		return -ENOMEM;
 	}
-	ret = ubd_setup_common(str, &n);
-	if (ret) {
-		ret = -1;
+
+	ret = ubd_setup_common(str, &n, error_out);
+	if (ret)
 		goto err_free;
-	}
+
 	if (n == -1) {
 		ret = 0;
 		goto err_free;
 	}
 
  	mutex_lock(&ubd_lock);
-	ret = ubd_add(n);
+	ret = ubd_add(n, error_out);
 	if (ret)
 		ubd_devs[n].file = NULL;
  	mutex_unlock(&ubd_lock);
@@ -777,7 +786,7 @@ static int ubd_id(char **str, int *start_out, int *end_out)
         return n;
 }
 
-static int ubd_remove(int n)
+static int ubd_remove(int n, char **error_out)
 {
 	struct ubd *ubd_dev;
 	int err = -ENODEV;
@@ -815,7 +824,9 @@ out:
 	return err;
 }
 
-/* All these are called by mconsole in process context and without ubd-specific locks. */
+/* All these are called by mconsole in process context and without
+ * ubd-specific locks.
+ */
 static struct mc_device ubd_mc = {
 	.name		= "ubd",
 	.config		= ubd_config,
@@ -851,7 +862,8 @@ static struct platform_driver ubd_driver = {
 
 static int __init ubd_init(void)
 {
-        int i;
+	char *error;
+	int i, err;
 
 	if (register_blkdev(MAJOR_NR, "ubd"))
 		return -1;
@@ -870,8 +882,12 @@ static int __init ubd_init(void)
 			return -1;
 	}
 	platform_driver_register(&ubd_driver);
-	for (i = 0; i < MAX_DEV; i++)
-		ubd_add(i);
+	for (i = 0; i < MAX_DEV; i++){
+		err = ubd_add(i, &error);
+		if(err)
+			printk(KERN_ERR "Failed to initialize ubd device %d :"
+			       "%s\n", i, error);
+	}
 	return 0;
 }
 
diff --git a/arch/um/include/chan_kern.h b/arch/um/include/chan_kern.h
index 9003a343e14..2d9aa7ef4c2 100644
--- a/arch/um/include/chan_kern.h
+++ b/arch/um/include/chan_kern.h
@@ -30,7 +30,7 @@ struct chan {
 extern void chan_interrupt(struct list_head *chans, struct delayed_work *task,
 			   struct tty_struct *tty, int irq);
 extern int parse_chan_pair(char *str, struct line *line, int device,
-			   const struct chan_opts *opts);
+			   const struct chan_opts *opts, char **error_out);
 extern int open_chan(struct list_head *chans);
 extern int write_chan(struct list_head *chans, const char *buf, int len,
 			     int write_irq);
diff --git a/arch/um/include/line.h b/arch/um/include/line.h
index b79643eeee0..a2486b4cc9f 100644
--- a/arch/um/include/line.h
+++ b/arch/um/include/line.h
@@ -76,7 +76,7 @@ struct lines {
 extern void line_close(struct tty_struct *tty, struct file * filp);
 extern int line_open(struct line *lines, struct tty_struct *tty);
 extern int line_setup(struct line *lines, unsigned int sizeof_lines,
-		      char *init);
+		      char *init, char **error_out);
 extern int line_write(struct tty_struct *tty, const unsigned char *buf,
 		      int len);
 extern void line_put_char(struct tty_struct *tty, unsigned char ch);
@@ -102,9 +102,11 @@ extern void lines_init(struct line *lines, int nlines, struct chan_opts *opts);
 extern void close_lines(struct line *lines, int nlines);
 
 extern int line_config(struct line *lines, unsigned int sizeof_lines,
-		       char *str, const struct chan_opts *opts);
+		       char *str, const struct chan_opts *opts,
+		       char **error_out);
 extern int line_id(char **str, int *start_out, int *end_out);
-extern int line_remove(struct line *lines, unsigned int sizeof_lines, int n);
+extern int line_remove(struct line *lines, unsigned int sizeof_lines, int n,
+		       char **error_out);
 extern int line_get_config(char *dev, struct line *lines,
 			   unsigned int sizeof_lines, char *str,
 			   int size, char **error_out);
diff --git a/arch/um/include/mconsole_kern.h b/arch/um/include/mconsole_kern.h
index 1ea6d928e1c..73030e52b2c 100644
--- a/arch/um/include/mconsole_kern.h
+++ b/arch/um/include/mconsole_kern.h
@@ -18,10 +18,10 @@ struct mconsole_entry {
 struct mc_device {
 	struct list_head list;
 	char *name;
-	int (*config)(char *);
+	int (*config)(char *, char **);
 	int (*get_config)(char *, char *, int, char **);
         int (*id)(char **, int *, int *);
-	int (*remove)(int);
+	int (*remove)(int, char **);
 };
 
 #define CONFIG_CHUNK(str, size, current, chunk, end) \
@@ -50,14 +50,3 @@ static inline void mconsole_register_dev(struct mc_device *new)
 #endif
 
 #endif
-
-/*
- * Overrides for Emacs so that we follow Linus's tabbing style.
- * Emacs will notice this stuff at the end of the file and automatically
- * adjust the settings for this buffer only.  This must remain at the end
- * of the file.
- * ---------------------------------------------------------------------------
- * Local variables:
- * c-file-style: "linux"
- * End:
- */
diff --git a/arch/um/kernel/tt/gdb.c b/arch/um/kernel/tt/gdb.c
index 786e4edd86c..8eba8f7dca6 100644
--- a/arch/um/kernel/tt/gdb.c
+++ b/arch/um/kernel/tt/gdb.c
@@ -139,7 +139,7 @@ static void config_gdb_cb(void *arg)
 	init_proxy(debugger_pid, 0, 0);
 }
 
-int gdb_config(char *str)
+int gdb_config(char *str, char **error_out)
 {
 	struct gdb_data data;
 
@@ -154,7 +154,7 @@ void remove_gdb_cb(void *unused)
 	exit_debugger_cb(NULL);
 }
 
-int gdb_remove(int unused)
+int gdb_remove(int unused, char **error_out)
 {
 	initial_thread_cb(remove_gdb_cb, NULL);
         return 0;
diff --git a/arch/um/kernel/tt/gdb_kern.c b/arch/um/kernel/tt/gdb_kern.c
index 68e1bf63cd0..a1af96ef9ee 100644
--- a/arch/um/kernel/tt/gdb_kern.c
+++ b/arch/um/kernel/tt/gdb_kern.c
@@ -8,8 +8,8 @@
 
 #ifdef CONFIG_MCONSOLE
 
-extern int gdb_config(char *str);
-extern int gdb_remove(int n);
+extern int gdb_config(char *str, char **error_out);
+extern int gdb_remove(int n, char **error_out);
 
 static struct mc_device gdb_mc = {
 	.name		= "gdb",