On Thu, Dec 09, 2021 at 06:23:49PM -0800, Jakub Kicinski wrote: > On Fri, 10 Dec 2021 00:03:40 +0100 Daniel Borkmann wrote: > > > Similar issue was discussed in the past. See: > > > https://lore.kernel.org/netdev/20191204.125135.750458923752225025.davem@xxxxxxxxxxxxx/ > > > > With regards to ENOTSUPP exposure, if the consensus is that we should fix all > > occurences over to EOPNOTSUPP even if they've been exposed for quite some time > > (Jakub?), > > Did you mean me? :) In case you did - I think we should avoid it > for new code but changing existing now seems risky. Alexei and Andrii > would know best but quick search of code bases at work reveals some > scripts looking for ENOTSUPP. > > Thadeu, what motivated the change? > > If we're getting those changes fixes based on checkpatch output maybe > there is a way to mute the checkpatch warnings when it's not run on a > diff? > It was not checkpatch that motivated me. I was looking into the following commits as we hit a failed test. be08815c5d3b ("bpf: add also cbpf long jump test cases with heavy expansion") 050fad7c4534 ("bpf: fix truncated jump targets on heavy expansions") Then, I realized that if given the right number of BPF_LDX | BPF_B | BPF_MSH instructions, it will pass the bpf_convert_filter stage, but fail at blinding. And if you have CONFIG_BPF_JIT_ALWAYS_ON, setting the filter will fail with ENOTSUPP, which should not be sent to userspace. I noticed other ENOTSUPP, but they seemed to be returned by helpers, and I was not sure this would be relayed to userspace. So, I went for fixing the observed case. I will see if any of the tests I can run is broken by this change and submit it again with the tests fixed as well. Cascardo. > > we could give this patch a try maybe via bpf-next and see if anyone complains. > > > > Thadeu, I think you also need to fix up BPF selftests as test_verifier, to mention > > one example (there are also bunch of others under tools/testing/selftests/), is > > checking for ENOTSUPP specifically..
