net: skb_frag_t can be smaller on small arches

On 32bit arches, if PAGE_SIZE is smaller than 65536, we can use 16bit
offset and size fields. This patch saves 72 bytes per skb on i386, or
128 bytes after rounding.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 0 deletions

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index b2c41d19735c..0b53c43ac92e 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -129,8 +129,13 @@ typedef struct skb_frag_struct skb_frag_t;
 
 struct skb_frag_struct {
         struct page *page;
+#if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536)
         __u32 page_offset;
         __u32 size;
+#else
+        __u16 page_offset;
+        __u16 size;
+#endif
 };
 
 #define HAVE_HW_TIME_STAMP