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Sender: Tejun Heo <htejun@gmail.com>
Date:   Fri, 20 May 2022 01:16:00 -1000
From:   Tejun Heo <tj@kernel.org>
To:     Kumar Kartikeya Dwivedi <memxor@gmail.com>
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Subject: Re: [PATCH bpf-next v1 2/5] cgroup: bpf: add cgroup_rstat_updated()
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On Fri, May 20, 2022 at 03:06:07PM +0530, Kumar Kartikeya Dwivedi wrote:
> With static noinline, the compiler will optimize away the function. With global
> noinline, it can still optimize away the call site, but will keep the function
> definition, so attach works. Therefore __weak is needed to ensure call is still
> emitted. With GCC __attribute__((noipa)) might have been more appropritate, but
> LLVM doesn't support it, so __weak is the next best thing supported by both with
> the same side effect.

Ah, okay, so it's to prevent compiler from optimizing away call to a noop
function by telling it that we don't know what the function might eventually
be. Thanks for the explanation. Yosry, can you please add a comment
explaining what's going on?

Thanks.

-- 
tejun