Hi,
On 14.07.21 12:39, Richard Weinberger wrote:
> Ahmad,
>
> ----- Ursprüngliche Mail -----
>> Von: "Ahmad Fatoum" <a.fatoum@xxxxxxxxxxxxxx>
>> Let's trade reviews to get the ball rolling?
>
> Sounds like a fair deal. :-)
:)
> [...]
>
>>> --- 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.
>
> [...]
>
>>> @@ -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.
>
> [...]
>
>>> +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.
>>> +
>>> + 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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