[PATCH] crypto: sl3516 - drop invalid sg_dma_len checks before DMA mapping

[PATCH] crypto: sl3516 - drop invalid sg_dma_len checks before DMA mapping

[Thorsten Blum]

sg_dma_len() is only valid after mapping the scatterlist with
dma_map_sg(). However, sl3516_ce_need_fallback() checks it before the
source and destination scatterlists are mapped. Thus, a stale DMA length
that is not a multiple of 16 could incorrectly force a software fallback
when CONFIG_NEED_SG_DMA_LENGTH=y.

Remove the invalid checks; the existing scatterlist length checks are
sufficient.

Fixes: 46c5338db7bd ("crypto: sl3516 - Add sl3516 crypto engine")
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
---
 drivers/crypto/gemini/sl3516-ce-cipher.c | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/drivers/crypto/gemini/sl3516-ce-cipher.c b/drivers/crypto/gemini/sl3516-ce-cipher.c
index 583010b2d007..02ec4282333b 100644
--- a/drivers/crypto/gemini/sl3516-ce-cipher.c
+++ b/drivers/crypto/gemini/sl3516-ce-cipher.c
@@ -56,10 +56,6 @@ static bool sl3516_ce_need_fallback(struct skcipher_request *areq)
 			ce->fallback_mod16++;
 			return true;
 		}
-		if ((sg_dma_len(sg) % 16) != 0) {
-			ce->fallback_mod16++;
-			return true;
-		}
 		if (!IS_ALIGNED(sg->offset, 16)) {
 			ce->fallback_align16++;
 			return true;
@@ -72,10 +68,6 @@ static bool sl3516_ce_need_fallback(struct skcipher_request *areq)
 			ce->fallback_mod16++;
 			return true;
 		}
-		if ((sg_dma_len(sg) % 16) != 0) {
-			ce->fallback_mod16++;
-			return true;
-		}
 		if (!IS_ALIGNED(sg->offset, 16)) {
 			ce->fallback_align16++;
 			return true;

Re: [PATCH] crypto: sl3516 - drop invalid sg_dma_len checks before DMA mapping

[Linus Walleij]

On Fri, Jul 10, 2026 at 9:42 AM Thorsten Blum <thorsten.blum@linux.dev> wrote:

> sg_dma_len() is only valid after mapping the scatterlist with
> dma_map_sg(). However, sl3516_ce_need_fallback() checks it before the
> source and destination scatterlists are mapped. Thus, a stale DMA length
> that is not a multiple of 16 could incorrectly force a software fallback
> when CONFIG_NEED_SG_DMA_LENGTH=y.
>
> Remove the invalid checks; the existing scatterlist length checks are
> sufficient.
>
> Fixes: 46c5338db7bd ("crypto: sl3516 - Add sl3516 crypto engine")
> Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>

Looks right to me.
Acked-by: Linus Walleij <linusw@kernel.org>

Yours,
Linus Walleij

Re: [PATCH] crypto: sl3516 - drop invalid sg_dma_len checks before DMA mapping

[Herbert Xu]

On Fri, Jul 10, 2026 at 09:42:17AM +0200, Thorsten Blum wrote:
> sg_dma_len() is only valid after mapping the scatterlist with
> dma_map_sg(). However, sl3516_ce_need_fallback() checks it before the
> source and destination scatterlists are mapped. Thus, a stale DMA length
> that is not a multiple of 16 could incorrectly force a software fallback
> when CONFIG_NEED_SG_DMA_LENGTH=y.
> 
> Remove the invalid checks; the existing scatterlist length checks are
> sufficient.
> 
> Fixes: 46c5338db7bd ("crypto: sl3516 - Add sl3516 crypto engine")
> Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
> ---
>  drivers/crypto/gemini/sl3516-ce-cipher.c | 8 --------
>  1 file changed, 8 deletions(-)

Patch applied.  Thanks.
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt