Re: [PATCH] RDMA/qedr: Explicitly cast pkt->tx_dest to qed_ll2_tx_dest

From: Nick Desaulniers
Date: Thu Sep 27 2018 - 16:28:27 EST


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?

>
> 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