Re: [PATCH v2 bpf 1/4] bpf: Fix pending_pos walk on 32-bit ring position wrap

> diff --git a/kernel/bpf/ringbuf.c b/kernel/bpf/ringbuf.c
> index 35ae64ade36b..06d3cc192601 100644
> --- a/kernel/bpf/ringbuf.c
> +++ b/kernel/bpf/ringbuf.c
> @@ -482,7 +482,7 @@ static void *__bpf_ringbuf_reserve(struct bpf_ringbuf *rb, u64 size)
>  	prod_pos = rb->producer_pos;
>  	new_prod_pos = prod_pos + len;
>
> -	while (pend_pos < prod_pos) {
> +	while (prod_pos - pend_pos > 0) {
>  		hdr = (void *)rb->data + (pend_pos & rb->mask);
>  		hdr_len = READ_ONCE(hdr->len);
>  		if (hdr_len & BPF_RINGBUF_BUSY_BIT)

This isn't a bug, but since both operands are unsigned long,
`prod_pos - pend_pos > 0` is the same as `pend_pos != prod_pos`.

Would spelling it that way (or `(long)(prod_pos - pend_pos) > 0` if an
ordering test is meant) make the intent clearer next to the
`- ... > rb->mask` comparisons above?


---
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See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md

CI run summary: https://github.com/kernel-patches/bpf/actions/runs/31802836964