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From: Leon Hwang <hffilwlqm@gmail.com>
To: Jiayuan Chen <jiayuan.chen@linux.dev>, bpf@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Martin KaFai Lau <martin.lau@linux.dev>,
	Eduard Zingerman <eddyz87@gmail.com>, Song Liu <song@kernel.org>,
	Yonghong Song <yonghong.song@linux.dev>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>,
	Stanislav Fomichev <sdf@fomichev.me>, Hao Luo <haoluo@google.com>,
	Jiri Olsa <jolsa@kernel.org>, Shuah Khan <shuah@kernel.org>,
	linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org
Subject: Re: [PATCH bpf-next v1 1/2] bpf: Add kfuncs for detecting execution context
Date: Wed, 22 Oct 2025 20:55:55 +0800	[thread overview]
Message-ID: <8764fe64-d896-460e-8e0c-cd81667c57b9@gmail.com> (raw)
In-Reply-To: <20251022113412.352307-2-jiayuan.chen@linux.dev>



On 2025/10/22 19:33, Jiayuan Chen wrote:
> This path introduces several kfuncs to help BPF programs determine their
> current execution context. When hooking functions for statistics, we often
> need to use current->comm to get the process name.
>
> However, these hooked functions can be called from either process context
> or interrupt context. When called from interrupt context, the current we
> obtain may refer to the process that was interrupted, which may not be
> what we need.
>
> These new kfuncs expose APIs that allow users to determine the actual
> execution context.

Hi Jiayuan,

Rather than introducing multiple kfuncs to determine the current
execution context, this can already be achieved by using the
'bpf_this_cpu_ptr()' helper to read the underlying preemption count.

Please refer to my earlier patch,
"selftests/bpf: Introduce experimental bpf_in_interrupt()"[1], which
demonstrates this approach.

Links:
[1] https://lore.kernel.org/bpf/20250903140438.59517-1-leon.hwang@linux.dev/

Thanks,
Leon

[...]

  reply	other threads:[~2025-10-22 12:56 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-10-22 11:33 [PATCH bpf-next v1 0/2] bpf: Add kfuncs and selftests for detecting execution context and selftests Jiayuan Chen
2025-10-22 11:33 ` [PATCH bpf-next v1 1/2] bpf: Add kfuncs for detecting execution context Jiayuan Chen
2025-10-22 12:55   ` Leon Hwang [this message]
2025-10-24 16:14   ` kernel test robot
2025-10-22 11:33 ` [PATCH bpf-next v1 2/2] selftests/bpf: Add selftests for context detection kfuncs Jiayuan Chen

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