Re: [PATCH net-next] net: Eliminate txhash in sock and reflect RX hash on transmit

On Fri, 2015-02-20 at 16:24 -0800, Tom Herbert wrote:

Instead of having a separate hash value in sock structure for transmit
and receive, we can use the rxhash value for both and eliminate the
txhash value. This simplifies the code and reflects the receive hash a
device provides to the stack for packets transmitted on the associated
connection. The hash value returned by a device could have meaning when
used in transmit to identify a flow, for instance the hash may be a flow
key for a flow created in a (virtual) device. With the flow key provided
on transmit this can obviate the need to create the hash and do the
lookup on the fly in transmit.

Wow. You just depleted entropy pool completely.

prandom_bytes() or prandom_u32() will just be fine.

Quite frankly, all these changes seem pointless, as you have no
guarantee same hash will be used for packets of a given flow.

Obviously the outgoing SYN packet has no easy way to know what will be
the rxhash in opposite direction. I think I already mentioned this
problem.

So whats the point ?