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In-Reply-To: <de6de430fd9bbc2d38ff2d5a1ce89983421b9dda.1662432407.git.pliem@maxlinear.com>
References: <de6de430fd9bbc2d38ff2d5a1ce89983421b9dda.1662432407.git.pliem@maxlinear.com>
Cc:     linux-crypto@vger.kernel.org, linux-lgm-soc@maxlinear.com,
        Peter Harliman Liem <pliem@maxlinear.com>
From:   Antoine Tenart <atenart@kernel.org>
Subject: Re: [PATCH v2 1/2] crypto: inside_secure - Avoid dma map if size is zero
To:     Peter Harliman Liem <pliem@maxlinear.com>,
        herbert@gondor.apana.org.au
Message-ID: <166247285388.3585.6290053542530090542@kwain>
Date:   Tue, 06 Sep 2022 16:00:53 +0200
Precedence: bulk

Quoting Peter Harliman Liem (2022-09-06 04:51:49)
> From commit d03c54419274 ("dma-mapping: disallow .map_sg
> operations from returning zero on error"), dma_map_sg()
> produces warning if size is 0. This results in visible
> warnings if crypto length is zero.
> To avoid that, we avoid calling dma_map_sg if size is zero.
>=20
> Fixes: d03c54419274 ("dma-mapping: disallow .map_sg operations from retur=
ning zero on error")

You can't reference the commit above, it's not introducing the issue but
the warning itself. The actual commit introducing the below logic should
be referenced.

Alternatively since the warning was introduced latter than the logic and
this is not a huge issue, you might resend it w/o the Fixes tag as well.

> Signed-off-by: Peter Harliman Liem <pliem@maxlinear.com>

With the Fixes: tag fixed,

Acked-by: Antoine Tenart <atenart@kernel.org>

Thanks!

> ---
> v2:
>  Add fixes tag
>=20
>  drivers/crypto/inside-secure/safexcel_cipher.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
>=20
> diff --git a/drivers/crypto/inside-secure/safexcel_cipher.c b/drivers/cry=
pto/inside-secure/safexcel_cipher.c
> index d68ef16650d4..3775497775e0 100644
> --- a/drivers/crypto/inside-secure/safexcel_cipher.c
> +++ b/drivers/crypto/inside-secure/safexcel_cipher.c
> @@ -737,14 +737,17 @@ static int safexcel_send_req(struct crypto_async_re=
quest *base, int ring,
>                                 max(totlen_src, totlen_dst));
>                         return -EINVAL;
>                 }
> -               dma_map_sg(priv->dev, src, sreq->nr_src, DMA_BIDIRECTIONA=
L);
> +               if (sreq->nr_src > 0)
> +                       dma_map_sg(priv->dev, src, sreq->nr_src, DMA_BIDI=
RECTIONAL);
>         } else {
>                 if (unlikely(totlen_src && (sreq->nr_src <=3D 0))) {
>                         dev_err(priv->dev, "Source buffer not large enoug=
h (need %d bytes)!",
>                                 totlen_src);
>                         return -EINVAL;
>                 }
> -               dma_map_sg(priv->dev, src, sreq->nr_src, DMA_TO_DEVICE);
> +
> +               if (sreq->nr_src > 0)
> +                       dma_map_sg(priv->dev, src, sreq->nr_src, DMA_TO_D=
EVICE);
> =20
>                 if (unlikely(totlen_dst && (sreq->nr_dst <=3D 0))) {
>                         dev_err(priv->dev, "Dest buffer not large enough =
(need %d bytes)!",
> @@ -753,7 +756,9 @@ static int safexcel_send_req(struct crypto_async_requ=
est *base, int ring,
>                                      DMA_TO_DEVICE);
>                         return -EINVAL;
>                 }
> -               dma_map_sg(priv->dev, dst, sreq->nr_dst, DMA_FROM_DEVICE);
> +
> +               if (sreq->nr_dst > 0)
> +                       dma_map_sg(priv->dev, dst, sreq->nr_dst, DMA_FROM=
_DEVICE);
>         }
> =20
>         memcpy(ctx->base.ctxr->data, ctx->key, ctx->key_len);
> --=20
> 2.17.1
>=20