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Date: Tue, 1 Sep 2026 10:13:27 -1000
From: Tejun Heo <tj@kernel.org>
To: Andrea Righi <arighi@nvidia.com>
Cc: Wanwu Li <liwanwu@kylinos.cn>, David Vernet <void@manifault.com>,
	Changwoo Min <changwoo@igalia.com>, sched-ext@lists.linux.dev,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] sched_ext: Reject NMI calls to lock-taking kfuncs
Message-ID: <apcx5yUysXEuEYAf@slm.duckdns.org>
References: <20260901095652.1009104-1-liwanwu@kylinos.cn>
 <apcsyS2j-N8j5-BN@gpd4>
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In-Reply-To: <apcsyS2j-N8j5-BN@gpd4>

Hello,

On Tue, Sep 01, 2026 at 09:51:37PM +0200, Andrea Righi wrote:
> AFAICS, the lock-taking and state-changing kfuncs do not have a meaningful use
> from BPF_PROG_TYPE_TRACING. We could move them out of scx_kfunc_ids_any into a
> separate set registered only for BPF_PROG_TYPE_STRUCT_OPS. The read-only kfuncs
> could remain available to tracing programs.
> 
> This should include:
>  - scx_bpf_kick_cpu() / scx_bpf_kick_cid()
>  - scx_bpf_destroy_dsq()
>  - scx_bpf_dsq_reenq() / scx_bpf_reenqueue_local___v2()
>  - bpf_iter_scx_dsq_{new,next,destroy}()
>  - scx_bpf_cpuperf_set() / scx_bpf_cidperf_set()
>  - scx_bpf_sub_grant() / scx_bpf_sub_revoke()
>  (... maybe others that I'm missing ...)

Hmm... but it *is* useful to be able to e.g. kick a CPU or trigger reenq
from a trace event, no?

Thanks.

-- 
tejun