[SK_BUFF]: Convert skb->tail to sk_buff_data_t

So that it is also an offset from skb->head, reduces its size from 8 to 4 bytes
on 64bit architectures, allowing us to combine the 4 bytes hole left by the
layer headers conversion, reducing struct sk_buff size to 256 bytes, i.e. 4
64byte cachelines, and since the sk_buff slab cache is SLAB_HWCACHE_ALIGN...
:-)

Many calculations that previously required that skb->{transport,network,
mac}_header be first converted to a pointer now can be done directly, being
meaningful as offsets or pointers.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 4 deletions

diff --git a/kernel/audit.c b/kernel/audit.c
index 76c9a11b72d6..ea8521417d13 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -1073,7 +1073,7 @@ static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
 			goto out;
 	}
 	va_copy(args2, args);
-	len = vsnprintf(skb->tail, avail, fmt, args);
+	len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
 	if (len >= avail) {
 		/* The printk buffer is 1024 bytes long, so if we get
 		 * here and AUDIT_BUFSIZ is at least 1024, then we can
@@ -1082,7 +1082,7 @@ static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
 			max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
 		if (!avail)
 			goto out;
-		len = vsnprintf(skb->tail, avail, fmt, args2);
+		len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
 	}
 	if (len > 0)
 		skb_put(skb, len);
@@ -1143,7 +1143,7 @@ void audit_log_hex(struct audit_buffer *ab, const unsigned char *buf,
 			return;
 	}
 
-	ptr = skb->tail;
+	ptr = skb_tail_pointer(skb);
 	for (i=0; i<len; i++) {
 		*ptr++ = hex[(buf[i] & 0xF0)>>4]; /* Upper nibble */
 		*ptr++ = hex[buf[i] & 0x0F];	  /* Lower nibble */
@@ -1175,7 +1175,7 @@ static void audit_log_n_string(struct audit_buffer *ab, size_t slen,
 		if (!avail)
 			return;
 	}
-	ptr = skb->tail;
+	ptr = skb_tail_pointer(skb);
 	*ptr++ = '"';
 	memcpy(ptr, string, slen);
 	ptr += slen;