Do not setsockopt(2) on AF_UNIX / AF_VSOCK sockets

[msanft]

With Linux 6.12, specifically this commit:
torvalds/linux@5b0af62, one can not call setsockopt(2) on non-inet (AF_INET/AF_INET6) sockets anymore. As the ttRPC socket can only ever be non-inet, we should not ever call setsockopt(2) here.

[Tim-Zhang]

Good catch, LGTM thanks @msanft,

This code was introduced by @wllenyj five years ago in a internal project and was ported by me on #48.

I suspect this is a misspelling of SO_REUSEADDR, however this line should not exist, it does not make any sense.

[stefano-garzarella]

With Linux 6.12, specifically this commit: torvalds/linux@5b0af62, one can not call setsockopt(2) on non-inet (AF_INET/AF_INET6) sockets anymore. As the ttRPC socket can only ever be non-inet, we should not ever call setsockopt(2) here.

Just to be clear here, you can call setsockopt(2) also to non-inet socket, what changed here is calling it with SO_REUSEPORT. It will fail now, but for example it was never really supported in AF_VSOCK (and AF_UNIX of course where there aren't port). See https://lore.kernel.org/regressions/CACW2H-7QEMKA+LUAzFJ+srmRCzSuLk2G7shWt0SGR9SfmxwOjA@mail.gmail.com/

[msanft]

Yeah, thanks for the addendum @stefano-garzarella. I should have made it more clear in my original post that this is specific to the way setsockopt(2) is used here in ttrpc-rust. (i.e. with SO_REUSEPORT)