Re: [PATCH] ath10k: fix a NULL vs IS_ERR() check

[Dan Carpenter <dan.carpenter@oracle.com>]

On Mon, Nov 26, 2018 at 10:24:38AM +0200, Kalle Valo wrote:
> Dan Carpenter <dan.carpenter@oracle.com> writes:
> 
> > The devm_memremap() function doesn't return NULLs, it returns error
> > pointers.
> >
> > Fixes: ba94c753ccb4 ("ath10k: add QMI message handshake for wcn3990 client")
> > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> > ---
> >  drivers/net/wireless/ath/ath10k/qmi.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/wireless/ath/ath10k/qmi.c b/drivers/net/wireless/ath/ath10k/qmi.c
> > index f0429bee35c2..37b3bd629f48 100644
> > --- a/drivers/net/wireless/ath/ath10k/qmi.c
> > +++ b/drivers/net/wireless/ath/ath10k/qmi.c
> > @@ -931,9 +931,9 @@ static int ath10k_qmi_setup_msa_resources(struct ath10k_qmi *qmi, u32 msa_size)
> >  		qmi->msa_mem_size = resource_size(&r);
> >  		qmi->msa_va = devm_memremap(dev, qmi->msa_pa, qmi->msa_mem_size,
> >  					    MEMREMAP_WT);
> > -		if (!qmi->msa_va) {
> > +		if (IS_ERR(qmi->msa_va)) {
> >  			dev_err(dev, "failed to map memory region: %pa\n", &r.start);
> > -			return -EBUSY;
> > +			return PTR_ERR(qmi->msa_va);
> 
> That's a very good find!
> 
> But how has this even worked before?

This only changes the error path.  Presumably it always succeeds in real
life.

regards,
dan carpenter