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>

1 files changed, 4 insertions, 5 deletions

diff --git a/arch/um/drivers/pcap_user.c b/arch/um/drivers/pcap_user.c
index cf996b82af56..e9809356c530 100644
--- a/arch/um/drivers/pcap_user.c
+++ b/arch/um/drivers/pcap_user.c
@@ -13,8 +13,6 @@
 #include "um_malloc.h"
 #include "user.h"
 
-#define MAX_PACKET (ETH_MAX_PACKET + ETH_HEADER_OTHER)
-
 #define PCAP_FD(p) (*(int *)(p))
 
 static int pcap_user_init(void *data, void *dev)
@@ -23,7 +21,8 @@ static int pcap_user_init(void *data, void *dev)
         pcap_t *p;
         char errors[PCAP_ERRBUF_SIZE];
 
-        p = pcap_open_live(pri->host_if, MAX_PACKET, pri->promisc, 0, errors);
+        p = pcap_open_live(pri->host_if, ETH_MAX_PACKET + ETH_HEADER_OTHER,
+                           pri->promisc, 0, errors);
         if (p == NULL) {
                 printk(UM_KERN_ERR "pcap_user_init : pcap_open_live failed - "
                        "'%s'\n", errors);
@@ -133,8 +132,8 @@ const struct net_user_info pcap_user_info = {
         .open           = pcap_open,
         .close          = NULL,
         .remove         = pcap_remove,
-        .set_mtu        = NULL,
         .add_address    = NULL,
         .delete_address = NULL,
-        .max_packet     = MAX_PACKET - ETH_HEADER_OTHER
+        .mtu            = ETH_MAX_PACKET,
+        .max_packet     = ETH_MAX_PACKET + ETH_HEADER_OTHER,
 };