Re: [PATCH net-next v2 04/12] net-timestamp: add static key to control the whole bpf extension

On Wed, Oct 16, 2024 at 2:31 PM Martin KaFai Lau [off-list ref] wrote:

On 10/15/24 6:04 PM, Jason Xing wrote:

quoted

To be honest, I considered how to disable the static key. Like you
said, I failed to find a good chance that I can accurately disable it.

It at least needs to be disabled whenever that bpf prog got detached.

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The bpf prog may be detached also. (IF) it ends up staying with the
cgroup/sockops interface, it should depend on the existing static key in
cgroup_bpf_enabled(CGROUP_SOCK_OPS) instead of adding another one.

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Are you suggesting that we need to remove the current static key? In
the previous thread, the reason why Willem came up with this idea is,
I think, to avoid affect the non-bpf timestamping feature.

Take a look at cgroup_bpf_enabled(CGROUP_SOCK_OPS). There is a static key. I am
saying to use that existing key. afaict, the newly added bpf_tstamp_control key
is mainly an optimization. Yes, cgroup_bpf_enabled(CGROUP_SOCK_OPS) is less
granular but it has the needed accounting to disable whenever the bpf prog got
detached, so better just reuse the cgroup_bpf_enabled(CGROUP_SOCK_OPS).

Good suggestion. Good thing is that I don't need to figure out a
proper place to disable it any more. I can directly use
cgroup_bpf_enabled(CGROUP_SOCK_OPS) to test if the timestamp should be
printed with BPF program loaded.

BTW, I found that we don't implement how to disable the ip4_min_ttl
static key. Sometimes, I'm confused whether we have to disable it at a
certain time.

Thanks,
Jason