[IPX]: Annotate and fix IPX checksum
Calculation of IPX checksum got buggered about 2.4.0. The old variant
mangled the packet; that got fixed, but calculation itself got buggered.
Restored the correct logics, fixed a subtle breakage we used to have even
back then: if the sum is 0 mod 0xffff, we want to return 0, not 0xffff.
The latter has special meaning for IPX (cheksum disabled). Observation
(and obvious fix) nicked from history of FreeBSD ipx_cksum.c...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/ipx.h b/include/net/ipx.h
index 4a423d2..c6b2ee6 100644
--- a/include/net/ipx.h
+++ b/include/net/ipx.h
@@ -26,8 +26,8 @@
#define IPX_MAX_PPROP_HOPS 8
struct ipxhdr {
- __u16 ipx_checksum __attribute__ ((packed));
-#define IPX_NO_CHECKSUM 0xFFFF
+ __be16 ipx_checksum __attribute__ ((packed));
+#define IPX_NO_CHECKSUM __constant_htons(0xFFFF)
__be16 ipx_pktsize __attribute__ ((packed));
__u8 ipx_tctrl;
__u8 ipx_type;