Hi,

On 14.07.21 12:39, Richard Weinberger wrote:

Ahmad,

----- Ursprüngliche Mail -----

quoted

Von: "Ahmad Fatoum" [off-list ref]
Let's trade reviews to get the ball rolling?

Sounds like a fair deal. :-)

:)

[...]

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--- a/drivers/crypto/mxs-dcp.c
+++ b/drivers/crypto/mxs-dcp.c

@@ -15,6 +15,7 @@
 #include <linux/platform_device.h>
 #include <linux/stmp_device.h>
 #include <linux/clk.h>
+#include <linux/mxs-dcp.h>

The CAAM specific headers are in <soc/fsl/*.h>.
Should this be done likewise here as well?

I have no preferences. If soc/fsl/ is the way to go, fine by me.

I think it's the more appropriate place, but if the maintainers
are fine with <linux/mxs-dcp.h>, I don't mind.

[...]

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@@ -219,15 +224,18 @@ static int mxs_dcp_run_aes(struct dcp_async_ctx *actx,
 	struct dcp *sdcp = global_sdcp;
 	struct dcp_dma_desc *desc = &sdcp->coh->desc[actx->chan];
 	struct dcp_aes_req_ctx *rctx = skcipher_request_ctx(req);
+	dma_addr_t src_phys, dst_phys, key_phys = {0};

Why = {0}; ? dma_addr_t is a scalar type and the value is always
written here before access.

Initializing a scalar with {} is allowed in C, the braces are optional.
I like the braces because it works even when the underlaying type changes.
But that's just a matter of taste.

key_phys is initialized because it triggered a false positive gcc warning
on one of my targets. Let me re-run again to be sure, the code saw a lot of
refactoring since that.
 
[...]
  

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+static int mxs_dcp_aes_setrefkey(struct crypto_skcipher *tfm, const u8 *key,
+				 unsigned int len)
+{
+	struct dcp_async_ctx *actx = crypto_skcipher_ctx(tfm);
+	int ret = -EINVAL;
+
+	if (len != DCP_PAES_KEYSIZE)
+		goto out;

Nitpick: there is no cleanup, so why not return -EINVAL here
and unconditionally return 0 below?

What is the benefit?

Similar to why you wouldn't write: 

  if (len == DCP_PAES_KEYSIZE) { 
  	/* longer code block */
  }

  return ret;

Code is easier to scan through with early-exits.

Usually I try to use goto to have a single exit point of a function
but I don't have a strong preference...

It's just a nitpick. I am fine with it either way.

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+
+	actx->key_len = len;
+	actx->refkey = true;
+
+	switch (key[0]) {
+	case DCP_PAES_KEY_SLOT0:
+	case DCP_PAES_KEY_SLOT1:
+	case DCP_PAES_KEY_SLOT2:
+	case DCP_PAES_KEY_SLOT3:
+	case DCP_PAES_KEY_UNIQUE:
+	case DCP_PAES_KEY_OTP:
+		memcpy(actx->key, key, len);
+		ret = 0;
+	}

In the error case you return -EINVAL below, but you still write
into actx. Is that intentional?

You mean acts->key_len and actk->refkey?
Is this a problem?

It's easier to reason about code when it doesn't leave objects
it operates on in invalid states on failure. Changing key_len,
but leaving actx->key uninitialized is surprising IMO.

I can't judge whether this is a problem in practice, but less
surprises are a worthwhile goal.

Cheers,
Ahmad

Thanks,
//richard

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