uml: network driver MTU cleanups

A bunch of MTU-related cleanups in the network code.

First, there is the addition of the notion of a maximally-sized packet, which
is the MTU plus headers.  This is used to size the skb that will receive a
packet.  This allows ether_adjust_skb to go away, as it was used to resize the
skb after it was allocated.

Since the skb passed into the low-level read routine is no longer resized, and
possibly reallocated, there, they (and the write routines) don't need to get
an sk_buff **.  They just need the sk_buff * now.  The callers of
ether_adjust_skb still need to do the skb_put, so that's now inlined.

The MAX_PACKET definitions in most of the drivers are gone.

The set_mtu methods were all the same and did nothing, so they can be
removed.

The ethertap driver had a typo which doubled the size of the packet rather
than adding two bytes to it.  It also wasn't defining its setup_size, causing
a zero-byte kmalloc and crash when the invalid pointer returned from kmalloc
was dereferenced.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 8 insertions, 9 deletions

diff --git a/arch/um/include/net_kern.h b/arch/um/include/net_kern.h
index 9237056b910..d843c7924a7 100644
--- a/arch/um/include/net_kern.h
+++ b/arch/um/include/net_kern.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
+ * Copyright (C) 2002 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  * Licensed under the GPL
  */
 
@@ -30,24 +30,24 @@ struct uml_net_private {
 	struct work_struct work;
 	int fd;
 	unsigned char mac[ETH_ALEN];
+	int max_packet;
 	unsigned short (*protocol)(struct sk_buff *);
 	int (*open)(void *);
 	void (*close)(int, void *);
 	void (*remove)(void *);
-	int (*read)(int, struct sk_buff **skb, struct uml_net_private *);
-	int (*write)(int, struct sk_buff **skb, struct uml_net_private *);
+	int (*read)(int, struct sk_buff *skb, struct uml_net_private *);
+	int (*write)(int, struct sk_buff *skb, struct uml_net_private *);
 
 	void (*add_address)(unsigned char *, unsigned char *, void *);
 	void (*delete_address)(unsigned char *, unsigned char *, void *);
-	int (*set_mtu)(int mtu, void *);
 	char user[0];
 };
 
 struct net_kern_info {
 	void (*init)(struct net_device *, void *);
 	unsigned short (*protocol)(struct sk_buff *);
-	int (*read)(int, struct sk_buff **skb, struct uml_net_private *);
-	int (*write)(int, struct sk_buff **skb, struct uml_net_private *);
+	int (*read)(int, struct sk_buff *skb, struct uml_net_private *);
+	int (*write)(int, struct sk_buff *skb, struct uml_net_private *);
 };
 
 struct transport {
@@ -62,7 +62,6 @@ struct transport {
 
 extern struct net_device *ether_init(int);
 extern unsigned short ether_protocol(struct sk_buff *);
-extern struct sk_buff *ether_adjust_skb(struct sk_buff *skb, int extra);
 extern int tap_setup_common(char *str, char *type, char **dev_name,
 			    char **mac_out, char **gate_addr);
 extern void register_transport(struct transport *new);
diff --git a/arch/um/include/net_user.h b/arch/um/include/net_user.h
index cfe7c50634b..63bee158cd8 100644
--- a/arch/um/include/net_user.h
+++ b/arch/um/include/net_user.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
+ * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  * Licensed under the GPL
  */
 
@@ -18,10 +18,10 @@ struct net_user_info {
 	int (*open)(void *);
 	void (*close)(int, void *);
 	void (*remove)(void *);
-	int (*set_mtu)(int mtu, void *);
 	void (*add_address)(unsigned char *, unsigned char *, void *);
 	void (*delete_address)(unsigned char *, unsigned char *, void *);
 	int max_packet;
+	int mtu;
 };
 
 extern void ether_user_init(void *data, void *dev);