On Mon, 27 Nov 2023 07:21:47 -0700 Ahmed Zaki wrote: > On 2023-11-21 16:33, Jakub Kicinski wrote: > > On Mon, 20 Nov 2023 13:56:09 -0700 Ahmed Zaki wrote: > >> + * @data: Extension for the RSS hash function. Valid values are one of the > >> + * %RXH_HFUNC_*. > > > > @data is way too generic. Can we call this key_xfrm? key_preproc? > > We manipulate the "input data" (protocol fields) not the key. I will > rename to "input_xfrm". Ugh, right! > >> +/* RSS hash function data > >> + * XOR the corresponding source and destination fields of each specified > >> + * protocol. Both copies of the XOR'ed fields are fed into the RSS and RXHASH > >> + * calculation. > >> + */ > >> +#define RXH_HFUNC_SYM_XOR (1 << 0) > > > > We need to mention somewhere that sym-xor is unsafe, per Alex's > > comments. > > I already added the following in Documentation/networking/scaling.rst: > > "The Symmetric-XOR" is a type of RSS algorithms that achieves this hash > symmetry by XORing the input source and destination fields of the IP > and/or L4 protocols. This, however, results in reduced input entropy and > could potentially be exploited." > > Or do you mean add it also to "uapi/linux/ethtool.h" ? Yes, a short mention in a comment next to the define. There's a good chance person looking at this will not notice the documentation in scaling.
