[PATCH 3.4 140/176] lib/checksum.c: fix carry in csum_tcpudp_nofold

[PATCH 3.4 140/176] lib/checksum.c: fix carry in csum_tcpudp_nofold

[lizf]

From: karl beldan <karl.beldan@gmail.com>

3.4.107-rc1 review patch.  If anyone has any objections, please let me know.

------------------


commit 150ae0e94634714b23919f0c333fee28a5b199d5 upstream.

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
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Zefan Li <lizefan@huawei.com>
---
 lib/checksum.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/lib/checksum.c b/lib/checksum.c
index 12dceb2..edbf473 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;
@@ -193,8 +202,7 @@ __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
-- 
1.9.1

Re: [PATCH 3.4 140/176] lib/checksum.c: fix carry in csum_tcpudp_nofold

[Karl Beldan]

On Thu, Apr 09, 2015 at 04:46:28PM +0800, lizf@kernel.org wrote:
> From: karl beldan <karl.beldan@gmail.com>
> 
> 3.4.107-rc1 review patch.  If anyone has any objections, please let me know.
> 
> ------------------
> 
> 
> commit 150ae0e94634714b23919f0c333fee28a5b199d5 upstream.
> 

Hi Zefan,

The above patch introduced a build error for some archs, please consider
applying 9ce357795ef208faa0d59894d9d119a7434e37f3 
"lib/checksum.c: fix build for generic csum_tcpudp_nofold" as well.
 
Karl

Re: [PATCH 3.4 140/176] lib/checksum.c: fix carry in csum_tcpudp_nofold

[David Miller]

From: Karl Beldan <karl.beldan@gmail.com>
Date: Thu, 9 Apr 2015 19:44:08 +0200

> On Thu, Apr 09, 2015 at 04:46:28PM +0800, lizf@kernel.org wrote:
>> From: karl beldan <karl.beldan@gmail.com>
>> 
>> 3.4.107-rc1 review patch.  If anyone has any objections, please let me know.
>> 
>> ------------------
>> 
>> 
>> commit 150ae0e94634714b23919f0c333fee28a5b199d5 upstream.
>> 
> 
> Hi Zefan,
> 
> The above patch introduced a build error for some archs, please consider
> applying 9ce357795ef208faa0d59894d9d119a7434e37f3 
> "lib/checksum.c: fix build for generic csum_tcpudp_nofold" as well.

+1

Re: [PATCH 3.4 140/176] lib/checksum.c: fix carry in csum_tcpudp_nofold

[Zefan Li]

On 2015/4/10 1:44, Karl Beldan wrote:
> On Thu, Apr 09, 2015 at 04:46:28PM +0800, lizf@kernel.org wrote:
>> From: karl beldan <karl.beldan@gmail.com>
>>
>> 3.4.107-rc1 review patch.  If anyone has any objections, please let me know.
>>
>> ------------------
>>
>>
>> commit 150ae0e94634714b23919f0c333fee28a5b199d5 upstream.
>>
> 
> Hi Zefan,
> 
> The above patch introduced a build error for some archs, please consider
> applying 9ce357795ef208faa0d59894d9d119a7434e37f3 
> "lib/checksum.c: fix build for generic csum_tcpudp_nofold" as well.
>  

Will fix. Thanks for the review!