Re: [PATCH v3 4/8] crypto: acomp - Add API to get a compression algorithm's batch-size.

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential
issue to consider:
- [Medium] crypto: acomp: batch_size gated on acomp_is_async() instead
  of REQ_SEG
--

commit 2fa95d403dcc5d6c7b702698b0e306a5d643d3b3
Author: Kanchana P. Sridhar <kanchanapsridhar2026@gmail.com>

crypto: acomp - Add API to get a compression algorithm's batch-size.

This commit adds a batch_size field to struct acomp_alg and introduces
crypto_acomp_batch_size() to query the maximum batch size supported by an
acomp transform.

> diff --git a/crypto/acompress.c b/crypto/acompress.c
> index ac4dc52668b89..df9e42f519c35 100644
> --- a/crypto/acompress.c
> +++ b/crypto/acompress.c
> @@ -327,6 +327,20 @@ int crypto_acomp_decompress(struct acomp_req *req)
>  }
>  EXPORT_SYMBOL_GPL(crypto_acomp_decompress);
>  
> +unsigned int crypto_acomp_batch_size(struct crypto_acomp *tfm)
> +{
> +	if (acomp_is_async(tfm) &&
> +	    (crypto_comp_alg_common(tfm)->base.cra_type == &crypto_acomp_type)) {
> +		struct acomp_alg *alg = crypto_acomp_alg(tfm);
> +
> +		if (alg && alg->batch_size > 1)
> +			return alg->batch_size;
> +	}
> +
> +	return 1;
> +}
> +EXPORT_SYMBOL_GPL(crypto_acomp_batch_size);

[Severity: Medium]
Should crypto_acomp_batch_size() check crypto_acomp_req_seg(tfm) (or
have crypto_register_acomp() enforce CRYPTO_ALG_REQ_SEG when batch_size
> 1) instead of gating on acomp_is_async(tfm)?

crypto_acomp_compress() dispatches segmented requests based on
crypto_acomp_req_seg(tfm):

crypto/acompress.c:crypto_acomp_compress() {
    ...
	if (req->unit_size && acomp_request_issg(req)) {
		if (!crypto_acomp_req_seg(tfm))
			return acomp_do_req_chain(req, true);

		return tfm->compress(req);
	}
    ...
}

If an asynchronous acomp_alg sets batch_size > 1 without setting
CRYPTO_ALG_REQ_SEG in cra_flags, crypto_acomp_batch_size() returns
alg->batch_size, but crypto_acomp_compress() routes batched requests
(req->slen > req->unit_size) to acomp_do_req_chain(), which fails with
-ENOSYS.  Conversely, requiring acomp_is_async(tfm) forces
crypto_acomp_batch_size() to return 1 for synchronous acomp_alg
transforms even when they set batch_size > 1 and CRYPTO_ALG_REQ_SEG.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261106072412.7909-1-kanchanapsridhar2026@gmail.com?part=4