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authorkarl beldan <karl.beldan@gmail.com>2015-01-28 10:58:11 +0100
committerDavid S. Miller <davem@davemloft.net>2015-01-28 22:32:33 -0800
commit150ae0e94634714b23919f0c333fee28a5b199d5 (patch)
treecb5c3fcc3b42f4e59e77721b61cbbc306aa0f9af
parent59ccaaaa49b5b096cdc1f16706a9f931416b2332 (diff)
downloadlinux-150ae0e94634714b23919f0c333fee28a5b199d5.tar.gz
lib/checksum.c: fix carry in csum_tcpudp_nofold
The carry from the 64->32bits folding was dropped, e.g with: saddr=0xFFFFFFFF daddr=0xFF0000FF len=0xFFFF proto=0 sum=1, csum_tcpudp_nofold returned 0 instead of 1. Signed-off-by: Karl Beldan <karl.beldan@rivierawaves.com> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Mike Frysinger <vapier@gentoo.org> Cc: netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--lib/checksum.c12
1 files changed, 10 insertions, 2 deletions
diff --git a/lib/checksum.c b/lib/checksum.c
index 129775eb6de6..fcf38943132c 100644
--- a/lib/checksum.c
+++ b/lib/checksum.c
@@ -47,6 +47,15 @@ static inline unsigned short from32to16(unsigned int x)
return x;
}
+static inline u32 from64to32(u64 x)
+{
+ /* add up 32-bit and 32-bit for 32+c bit */
+ x = (x & 0xffffffff) + (x >> 32);
+ /* add up carry.. */
+ x = (x & 0xffffffff) + (x >> 32);
+ return (u32)x;
+}
+
static unsigned int do_csum(const unsigned char *buff, int len)
{
int odd;
@@ -195,8 +204,7 @@ __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
#else
s += (proto + len) << 8;
#endif
- s += (s >> 32);
- return (__force __wsum)s;
+ return (__force __wsum)from64to32(s);
}
EXPORT_SYMBOL(csum_tcpudp_nofold);
#endif