linux-kernel - Re: [PATCH] bpf: add bpf_msleep

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Message-ID: <nvaiideqcaqjvhdshhrcazg6g7horprlwa5f3fkk3x33f24wdq@zvqe4p6s3bpb>
Date: Tue, 6 May 2025 11:29:32 +0900
From: Sergey Senozhatsky <senozhatsky@...omium.org>
To: Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc: Sergey Senozhatsky <senozhatsky@...omium.org>, 
	Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, 
	John Fastabend <john.fastabend@...il.com>, Martin KaFai Lau <martin.lau@...ux.dev>, 
	Eduard Zingerman <eddyz87@...il.com>, Song Liu <song@...nel.org>, bpf@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] bpf: add bpf_msleep_interruptible()

On (25/05/05 12:55), Andrii Nakryiko wrote:
[..]
> I understand the appeal, don't get me wrong, but we have no way to
> enforce "is expected to be used for testing only". It's also all too
> easy to sleep for a really long time, and there isn't really any
> reasonable limit that would mitigate this, IMO.

Sure, I understand your concerns.

> If I had to do this for my own testing/fuzzing needs, I'd probably try
> to go with a custom kfunc provided by my small and trivial kernel
> module (modules can extend BPF with custom kfuncs). And see if it's
> useful.

A downstream kernel module?  I guess I can give it a try.

> One other alternative to enforce the "for testing only" aspect might
> be a custom kernel config, that would be expected to not make it into
> production. Though I'd start with the kernel module approach first,
> probably.

Something like `Depends on: DEBUG_KERNEL` maybe?