On Mon, 30 Sep 2019 15:17:02 +0100
Jonathan Cameron <jonathan.cameron@xxxxxxxxxx> wrote:
> On Mon, 30 Sep 2019 16:49:21 +0800
> Tian Tao <tiantao6@xxxxxxxxxx> wrote:
>
> > This patch fixes the following warnings:
> > drivers/crypto/ccree/cc_aead.c:630:5-12: WARNING: Unsigned expression
> > compared with zero: seq_len > 0
> >
> > Signed-off-by: Tian Tao <tiantao6@xxxxxxxxxx>
>
> Apologies, I should have looked into this in more depth when you asked
> me about it earlier rather than assuming it was 'obviously' the right
> fix.
>
> It's more complex than I expected given the warning, which I note
> is > 0 so it's not always true. I'm curious, which compiler generates
> that warning?
>
> So there are two ways seq_len can be set to non 0, hmac_setkey which returns a
> signed int, but one that is reality is >= 0. The other is xcbc_setkey
> which returns an unsigned int.
>
> So I would suggest that in addition to what you have here, a change
> to the return type of hmac_setkey in order to make it clear that
> never returns a negative anyway.
Hmm. Perhaps I shouldn't review with jetlag... That should have said
that I think the variable should be left unsigned as reality is that
it is always >= 0.
>
> Can also use if (seq_len)
> rather than if (seq_len > 0)
>
> Thanks,
>
> Jonathan
>
>
>
> > ---
> > drivers/crypto/ccree/cc_aead.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/crypto/ccree/cc_aead.c b/drivers/crypto/ccree/cc_aead.c
> > index d3e8faa..b19291d 100644
> > --- a/drivers/crypto/ccree/cc_aead.c
> > +++ b/drivers/crypto/ccree/cc_aead.c
> > @@ -546,7 +546,7 @@ static int cc_aead_setkey(struct crypto_aead *tfm, const u8 *key,
> > struct cc_aead_ctx *ctx = crypto_aead_ctx(tfm);
> > struct cc_crypto_req cc_req = {};
> > struct cc_hw_desc desc[MAX_AEAD_SETKEY_SEQ];
> > - unsigned int seq_len = 0;
> > + int seq_len = 0;
> > struct device *dev = drvdata_to_dev(ctx->drvdata);
> > const u8 *enckey, *authkey;
> > int rc;
>
