talos-op-linux/include/net/checksum.h, branch v4.0

net: Fix remcsum in GRO path to not change packet

2015-02-11T23:12:09+00:00

Remote checksum offload processing is currently the same for both the GRO and non-GRO path. When the remote checksum offload option is encountered, the checksum field referred to is modified in the packet. So in the GRO case, the packet is modified in the GRO path and then the operation is skipped when the packet goes through the normal path based on skb->remcsum_offload. There is a problem in that the packet may be modified in the GRO path, but then forwarded off host still containing the remote checksum option. A remote host will again perform RCO but now the checksum verification will fail since GRO RCO already modified the checksum. To fix this, we ensure that GRO restores a packet to it's original state before returning. In this model, when GRO processes a remote checksum option it still changes the checksum per the algorithm but on return from lower layer processing the checksum is restored to its original value. In this patch we add define gro_remcsum structure which is passed to skb_gro_remcsum_process to save offset and delta for the checksum being changed. After lower layer processing, skb_gro_remcsum_cleanup is called to restore the checksum before returning from GRO. Signed-off-by: Tom Herbert Signed-off-by: David S. Miller

net: Add remcsum_adjust as common function for remote checksum offload

2014-11-26T17:25:43+00:00

This function does the work to update a checksum field as part of remote checksum offload. remcsum_adjust does the following: 1) Subtract out the calculated checksum from the beginning of the packet (ptr arg) to the start offset. 2) Adjust the checksum field indicated by offset based on the modified checksum value from above step. 3) Return the difference in the old checksum field value and the new one. The caller will use this to update skb->csum and NAPI csum. Signed-off-by: Tom Herbert Signed-off-by: David S. Miller

net: optimise csum_replace4()

2014-09-26T20:14:16+00:00

csum_partial() is a generic function which is not optimised for small fixed length calculations, and its use requires to store "from" and "to" values in memory while we already have them available in registers. This also has impact, especially on RISC processors. In the same spirit as the change done by Eric Dumazet on csum_replace2(), this patch rewrites inet_proto_csum_replace4() taking into account RFC1624. I spotted during a NATted tcp transfert that csum_partial() is one of top 5 consuming functions (around 8%), and the second user of csum_partial() is inet_proto_csum_replace4(). I have proposed the same modification to inet_proto_csum_replace4() in another patch. Signed-off-by: Christophe Leroy Acked-by: Eric Dumazet Signed-off-by: David S. Miller

net: Allow csum_add to be provided in arch

2014-05-05T19:26:29+00:00

csum_add is really nothing more then add-with-carry which can be implemented efficiently in some architectures. Allow architecture to define this protected by HAVE_ARCH_CSUM_ADD. Signed-off-by: Tom Herbert Signed-off-by: David S. Miller

net: optimize csum_replace2()

2014-03-24T04:18:44+00:00

When changing one 16bit value by another in IP header, we can adjust the IP checksum by doing a simple operation described in RFC 1624, as reminded by David. csum_partial() is a complex function on x86_64, not really suited for small number of checksummed bytes. I spotted csum_partial() being in the top 20 most consuming functions (more than 1 %) in a GRO workload, which was rather unexpected. The caller was inet_gro_complete() doing a csum_replace2() when building the new IP header for the GRO packet. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

net: checksum: fix warning in skb_checksum

2013-11-04T20:27:08+00:00

This patch fixes a build warning in skb_checksum() by wrapping the csum_partial() usage in skb_checksum(). The problem is that on a few architectures, csum_partial is used with prefix asmlinkage whereas on most architectures it's not. So fix this up generically as we did with csum_block_add_ext() to match the signature. Introduced by 2817a336d4d ("net: skb_checksum: allow custom update/combine for walking skb"). Reported-by: Fengguang Wu Signed-off-by: Daniel Borkmann Signed-off-by: David S. Miller

net: skb_checksum: allow custom update/combine for walking skb

2013-11-04T04:04:57+00:00

Currently, skb_checksum walks over 1) linearized, 2) frags[], and 3) frag_list data and calculats the one's complement, a 32 bit result suitable for feeding into itself or csum_tcpudp_magic(), but unsuitable for SCTP as we're calculating CRC32c there. Hence, in order to not re-implement the very same function in SCTP (and maybe other protocols) over and over again, use an update() + combine() callback internally to allow for walking over the skb with different algorithms. Signed-off-by: Daniel Borkmann Signed-off-by: David S. Miller

checksum: Remove extern from function prototypes

2013-08-01T00:50:02+00:00

There are a mix of function prototypes with and without extern in the kernel sources. Standardize on not using extern for function prototypes. Function prototypes don't need to be written with extern. extern is assumed by the compiler. Its use is as unnecessary as using auto to declare automatic/local variables in a block. Signed-off-by: Joe Perches Signed-off-by: David S. Miller

net: core: add function for incremental IPv6 pseudo header checksum updates

2012-08-30T01:00:16+00:00

Add inet_proto_csum_replace16 for incrementally updating IPv6 pseudo header checksums for IPv6 NAT. Signed-off-by: Patrick McHardy Acked-by: David S. Miller

include/net net/ - csum_partial - remove unnecessary casts

2008-11-19T23:44:53+00:00

The first argument to csum_partial is const void * casts to char/u8 * are not necessary Signed-off-by: Joe Perches Signed-off-by: David S. Miller