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Date: Thu, 14 Dec 2023 18:22:09 -0800
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Subject: Re: [PATCH bpf-next v13 04/14] bpf: add struct_ops_tab to btf.
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To: thinker.li@gmail.com
Cc: sinquersw@gmail.com, kuifeng@meta.com, bpf@vger.kernel.org,
 ast@kernel.org, song@kernel.org, kernel-team@meta.com, andrii@kernel.org,
 drosen@google.com
References: <20231209002709.535966-1-thinker.li@gmail.com>
 <20231209002709.535966-5-thinker.li@gmail.com>
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From: Martin KaFai Lau <martin.lau@linux.dev>
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On 12/8/23 4:26 PM, thinker.li@gmail.com wrote:
> +const struct bpf_struct_ops_desc *btf_get_struct_ops(struct btf *btf, u32 *ret_cnt)
> +{
> +	if (!btf)
> +		return NULL;
> +	if (!btf->struct_ops_tab)

		*ret_cnt = 0;

unless the later patch checks the return value NULL before using *ret_cnt.
Anyway, better to set *ret_cnt to 0 if the btf has no struct_ops.

The same should go for the "!btf" case above but I suspect the above !btf check 
is unnecessary also and the caller should have checked for !btf itself instead 
of expecting a list of struct_ops from a NULL btf. Lets continue the review on 
the later patches for now to confirm where the above !btf case might happen.

> +		return NULL;
> +
> +	*ret_cnt = btf->struct_ops_tab->cnt;
> +	return (const struct bpf_struct_ops_desc *)btf->struct_ops_tab->ops;
> +}