mirror of
https://github.com/torvalds/linux.git
synced 2024-10-23 05:30:55 +00:00
17f1034dd7
Add the ability to send and receive packets that are larger than the size of a umem frame, using the AF_XDP /XDP multi-buffer support. There are three pieces of code that need to be changed to achieve this: the Rx path, the Tx path, and the validation logic. Both the Rx path and Tx could only deal with a single fragment per packet. The Tx path is extended with a new function called pkt_nb_frags() that can be used to retrieve the number of fragments a packet will consume. We then create these many fragments in a loop and fill the N-1 first ones to the max size limit to use the buffer space efficiently, and the Nth one with whatever data that is left. This goes on until we have filled in at the most BATCH_SIZE worth of descriptors and fragments. If we detect that the next packet would lead to BATCH_SIZE number of fragments sent being exceeded, we do not send this packet and finish the batch. This packet is instead sent in the next iteration of BATCH_SIZE fragments. For Rx, we loop over all fragments we receive as usual, but for every descriptor that we receive we call a new validation function called is_frag_valid() to validate the consistency of this fragment. The code then checks if the packet continues in the next frame. If so, it loops over the next packet and performs the same validation. once we have received the last fragment of the packet we also call the function is_pkt_valid() to validate the packet as a whole. If we get to the end of the batch and we are not at the end of the current packet, we back out the partial packet and end the loop. Once we get into the receive loop next time, we start over from the beginning of that packet. This so the code becomes simpler at the cost of some performance. The validation function is_frag_valid() checks that the sequence and packet numbers are correct at the start and end of each fragment. Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com> Link: https://lore.kernel.org/r/20230719132421.584801-19-maciej.fijalkowski@intel.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
||
|---|---|---|
| .. | ||
| asm | ||
| asm-generic | ||
| linux | ||
| nolibc | ||
| tools | ||
| trace/events | ||
| uapi | ||
| vdso | ||