net: remove osize variable in __alloc_skb()

This is a cleanup patch, to prepare following change.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/core/skbuff.c

@@ -533,7 +533,6 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
 {
 	struct kmem_cache *cache;
 	struct sk_buff *skb;
-	unsigned int osize;
 	bool pfmemalloc;
 	u8 *data;
 
@@ -559,24 +558,23 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
 	 * Both skb->head and skb_shared_info are cache line aligned.
 	 */
 	size = SKB_HEAD_ALIGN(size);
-	osize = kmalloc_size_roundup(size);
-	data = kmalloc_reserve(osize, gfp_mask, node, &pfmemalloc);
+	size = kmalloc_size_roundup(size);
+	data = kmalloc_reserve(size, gfp_mask, node, &pfmemalloc);
 	if (unlikely(!data))
 		goto nodata;
 	/* kmalloc_size_roundup() might give us more room than requested.
 	 * Put skb_shared_info exactly at the end of allocated zone,
 	 * to allow max possible filling before reallocation.
 	 */
-	size = SKB_WITH_OVERHEAD(osize);
-	prefetchw(data + size);
+	prefetchw(data + SKB_WITH_OVERHEAD(size));
 
 	/*
 	 * Only clear those fields we need to clear, not those that we will
 	 * actually initialise below. Hence, don't put any more fields after
 	 * the tail pointer in struct sk_buff!
 	 */
 	memset(skb, 0, offsetof(struct sk_buff, tail));
-	__build_skb_around(skb, data, osize);
+	__build_skb_around(skb, data, size);
 	skb->pfmemalloc = pfmemalloc;
 
 	if (flags & SKB_ALLOC_FCLONE) {