From: Martin KaFai Lau <martin.lau@linux.dev>
To: Ivan Babrou <ivan@cloudflare.com>
Cc: bpf <bpf@vger.kernel.org>,
kernel-team <kernel-team@cloudflare.com>,
Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Stanislav Fomichev <sdf@google.com>,
Martin KaFai Lau <kafai@fb.com>
Subject: Re: bpf_sk_cgroup_id is not available in tracepoints
Date: Tue, 1 Aug 2023 16:17:49 -0700 [thread overview]
Message-ID: <97511804-ea81-67aa-3120-92415b0be5df@linux.dev> (raw)
In-Reply-To: <CABWYdi1KERLa9dOK8mxxdNvT746R8adFHxuN53VMvWMS=yyq_w@mail.gmail.com>
On 8/1/23 2:59 PM, Ivan Babrou wrote:
> I noticed that bpf_sk_cgroup_id is not available in a tracepoint (it
> is only available in cgroup related skb filters), even though I can
> easily do what it does manually:
>
> u64 cgroup_id = sk->sk_cgrp_data.cgroup->kn->id;
>
> It seems to me that bpf_sk_cgroup_id and similar functions should be
> added to bpf_base_func_proto (unless there's a better place).
This will make it available to all tracing progs. How to ensure doing
'sk->sk_cgrp_data.cgroup->kn->id' is safe in all traceable context? so please
don't do that.
bpf will handle the exception when the bpf prog reads 'sk->...' (eg. in case sk
is an invalid ptr), so please keep using it for tracing programs.
prev parent reply other threads:[~2023-08-01 23:18 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-01 21:59 bpf_sk_cgroup_id is not available in tracepoints Ivan Babrou
2023-08-01 23:17 ` Martin KaFai Lau [this message]
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