Re: [PATCH] RDMA/qedr: Explicitly cast pkt->tx_dest to qed_ll2_tx_dest
From: Nathan Chancellor
Date: Thu Sep 27 2018 - 16:35:08 EST
On Thu, Sep 27, 2018 at 01:28:12PM -0700, Nick Desaulniers wrote:
> On Wed, Sep 26, 2018 at 6:18 PM Nathan Chancellor
> <natechancellor@xxxxxxxxx> wrote:
> >
> > Clang warns when one enumerated type is explicitly converted to another.
> >
> > drivers/infiniband/hw/qedr/qedr_roce_cm.c:198:28: warning: implicit
> > conversion from enumeration type 'enum qed_roce_ll2_tx_dest' to
> > different enumeration type 'enum qed_ll2_tx_dest' [-Wenum-conversion]
> > ll2_tx_pkt.tx_dest = pkt->tx_dest;
> > ~ ~~~~~^~~~~~~
> > 1 warning generated.
> >
> > Avoid this warning by explicitly casting pkt->tx_dest to
> > qed_112_tx_dest, which has the expected values from the
> > type qed_roce_ll2_tx_dest.
>
> But these enums are different lengths, which is problematic for this
> patch. Is this code broken, or that it's ok for ll2_tx_pkt.tx_dest to
> have a value that's not a valid enumeration value for enum
> qed_ll2_tx_dest? (QED_LL2_TX_DEST_MAX 's value (3) is outside the
> enumeration values of enum qed_roce_ll2_tx_dest).
>
> include/linux/qed/qed_rdma_if.h:
> 42 enum qed_roce_ll2_tx_dest {
> 43 /* Light L2 TX Destination to the Network */
> 44 QED_ROCE_LL2_TX_DEST_NW,
> 45
> 46 /* Light L2 TX Destination to the Loopback */
> 47 QED_ROCE_LL2_TX_DEST_LB,
> 48 QED_ROCE_LL2_TX_DEST_MAX
> 49 };
>
> include/linux/qed/qed_ll2_if.h:
> 64 enum qed_ll2_tx_dest {
> 65 QED_LL2_TX_DEST_NW, /* Light L2 TX Destination to the
> Network */
> 66 QED_LL2_TX_DEST_LB, /* Light L2 TX Destination to the
> Loopback */
> 67 QED_LL2_TX_DEST_DROP, /* Light L2 Drop the TX packet */
> 68 QED_LL2_TX_DEST_MAX
> 69 };
>
> Maybe the maintainers can clarify?
>
My assumption was that if QED_ROCE_LL2_TX_DEST_MAX was used that the
packet would be dropped.
Turns out that QED_ROCE_LL2_TX_DEST_MAX isn't actually used anywhere in
the tree. I suppose that qed_roce_ll2_tx_dest could just be removed and
all other instances of those values could be converted to
qed_ll2_tx_dest like the rxe patch. I'll test this now and send a patch
along if it works out.
Nathan
> >
> > Reported-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
> > Signed-off-by: Nathan Chancellor <natechancellor@xxxxxxxxx>
> > ---
> > drivers/infiniband/hw/qedr/qedr_roce_cm.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/infiniband/hw/qedr/qedr_roce_cm.c b/drivers/infiniband/hw/qedr/qedr_roce_cm.c
> > index 85578887421b..147e0d69003d 100644
> > --- a/drivers/infiniband/hw/qedr/qedr_roce_cm.c
> > +++ b/drivers/infiniband/hw/qedr/qedr_roce_cm.c
> > @@ -195,7 +195,7 @@ static int qedr_ll2_post_tx(struct qedr_dev *dev,
> >
> > ll2_tx_pkt.num_of_bds = 1 /* hdr */ + pkt->n_seg;
> > ll2_tx_pkt.vlan = 0;
> > - ll2_tx_pkt.tx_dest = pkt->tx_dest;
> > + ll2_tx_pkt.tx_dest = (enum qed_ll2_tx_dest)pkt->tx_dest;
> > ll2_tx_pkt.qed_roce_flavor = roce_flavor;
> > ll2_tx_pkt.first_frag = pkt->header.baddr;
> > ll2_tx_pkt.first_frag_len = pkt->header.len;
> > --
> > 2.19.0
> >
>
>
> --
> Thanks,
> ~Nick Desaulniers