Add SO_PREFER_BUSY_POLL and SO_BUSY_POLL_BUDGET

[tammela]

Remove the comment of these socket options.
Reference: https://elixir.bootlin.com/linux/latest/source/include/uapi/asm-generic/socket.h

[rustbot]

r? @tgross35

rustbot has assigned @tgross35.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

[tammela]

From the CI results (i686-unknown-linux-musl) it seems like the machine does not have a uapi header with the constant.
They were added in 5.11 and the sanitized headers are in 4.19: https://github.com/rust-lang/libc/blob/main/ci/install-musl.sh#L68

[devnexen]

for the time being, need to add those constants as exception (for CI), as if musl then ignore those two.

[tammela]

@devnexen Got it. I was wondering if someone tried to update the kernel headers for the musl CI.
Alpine uses musl as well and they don't seem to use sabotage-linux headers but rather roll their own (currently targeting 6.6 soon to be 6.10):
https://git.alpinelinux.org/aports/tree/main/linux-headers?h=master

[tammela]

I updated the CI to use the alpine headers here: tammela@17af7ba

Seems to be passing the CI scripts, let me know if it's worth the shot and I can open up a PR

[devnexen]

nice, it might be best to create a PR for this musl update alone tough. cc @tgross35

[tgross35]

Huh, no clue why those were commented out but looks like it has been that way since #2135. Anyway lgtm, thanks for including the link.

[tammela]

Needs this one to pass CI: #3921

[tgross35]

#3921 should be merged soon, would you mind rebasing to resolve conflicts?

Also, could you add these to the semver tests at libc-test/semver/linux.txt?

[tammela]

I will double check CI

[tammela]

So musl for some reason hard codes the socket constants instead of fetching them from the OS:
https://git.musl-libc.org/cgit/musl/tree/include/sys/socket.h#n293

I will look for a way to test these constants only on gnu libc

[bors]

☔ The latest upstream changes (presumably #4132) made this pull request unmergeable. Please resolve the merge conflicts.

[tgross35]

It looks like CI is passing - is this ready to be merged or is there something else to be done? (I've held off because of the labels)

[tammela]

It looks like CI is passing - is this ready to be merged or is there something else to be done? (I've held off because of the labels)

I gave in and gated the new constants for !musl. So it should be good from my side.
Musl made the decision to hardcode the SO_ constants instead of inherit them from the OS via #include <asm-generic/socket.h>.
Essentially updating the kernel headers is not enough, you have to hope a recent musl version kept up with the new constants...
The next musl version update will likely fill in the gap (till 70), but linux already added a bunch more :)

[tgross35]

Could you instead add these to linux-gnu.txt or linux-gnu-x86_64.txt instead?

Since there is something left to do, maybe leave a // FIXME(musl) in the .rs file rather than using the TODO semver.

[tammela]

Good catch, will do!

[tgross35]

I think it needs to go in one of the linux-gnu* files rather than linux-{arch} since these aren't yet available on musl

[tammela]

I added to the x86 one, but it should be fine for everything except musl, but it doesn't seem to have such a file