Re: [PATCH v5 2/4] net/bnx2x: fix warnings about rte_memcpy lengths

["Stanisław Kardach" <kda@semihalf.com>]

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On Wed, Dec 28, 2022, 16:10 Morten Brørup <mb@smartsharesystems.com> wrote:

> Bugfix: The vlan in the bulletin does not contain a VLAN header, only the
> VLAN ID, so only copy 2 byte, not 4. The target structure has padding
> after the field, so copying 2 byte too many is effectively harmless.
>
It is a small nitpick but why use rte_memcpy for a 2 byte / half-word copy?
Shouldn't assignment with casts be enough?

> There is no need to backport this patch.
>
> Use RTE_PTR_ADD where copying arrays to the offset of a first field in a
> structure holding multiple fields, to avoid compiler warnings.
>
> Bugzilla ID: 1146
>
> Signed-off-by: Morten Brørup <mb@smartsharesystems.com>
>
> v5:
> * No changes.
> v4:
> * Type casting did not fix the warnings, so use RTE_PTR_ADD instead.
> v3:
> * First patch in series.
> ---
>  drivers/net/bnx2x/bnx2x_stats.c | 11 +++++++----
>  drivers/net/bnx2x/bnx2x_vfpf.c  |  2 +-
>  2 files changed, 8 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/net/bnx2x/bnx2x_stats.c
> b/drivers/net/bnx2x/bnx2x_stats.c
> index c07b01510a..1c44504663 100644
> --- a/drivers/net/bnx2x/bnx2x_stats.c
> +++ b/drivers/net/bnx2x/bnx2x_stats.c
> @@ -819,8 +819,9 @@ bnx2x_hw_stats_update(struct bnx2x_softc *sc)
>
>      rte_memcpy(old, new, sizeof(struct nig_stats));
>
> -    rte_memcpy(&(estats->rx_stat_ifhcinbadoctets_hi),
> &(pstats->mac_stx[1]),
> -          sizeof(struct mac_stx));
> +    rte_memcpy(RTE_PTR_ADD(estats,
> +          offsetof(struct bnx2x_eth_stats, rx_stat_ifhcinbadoctets_hi)),
> +          &(pstats->mac_stx[1]), sizeof(struct mac_stx));
>      estats->brb_drop_hi = pstats->brb_drop_hi;
>      estats->brb_drop_lo = pstats->brb_drop_lo;
>
> @@ -1492,9 +1493,11 @@ bnx2x_stats_init(struct bnx2x_softc *sc)
>                 REG_RD(sc, NIG_REG_STAT0_BRB_TRUNCATE + port*0x38);
>         if (!CHIP_IS_E3(sc)) {
>                 REG_RD_DMAE(sc, NIG_REG_STAT0_EGRESS_MAC_PKT0 + port*0x50,
> -
>  &(sc->port.old_nig_stats.egress_mac_pkt0_lo), 2);
> +                               RTE_PTR_ADD(&(sc->port.old_nig_stats),
> +                               offsetof(struct nig_stats,
> egress_mac_pkt0_lo)), 2);
>                 REG_RD_DMAE(sc, NIG_REG_STAT0_EGRESS_MAC_PKT1 + port*0x50,
> -
>  &(sc->port.old_nig_stats.egress_mac_pkt1_lo), 2);
> +                               RTE_PTR_ADD(&(sc->port.old_nig_stats),
> +                               offsetof(struct nig_stats,
> egress_mac_pkt1_lo)), 2);
>         }
>
>         /* function stats */
> diff --git a/drivers/net/bnx2x/bnx2x_vfpf.c
> b/drivers/net/bnx2x/bnx2x_vfpf.c
> index 63953c2979..87631c76ca 100644
> --- a/drivers/net/bnx2x/bnx2x_vfpf.c
> +++ b/drivers/net/bnx2x/bnx2x_vfpf.c
> @@ -54,7 +54,7 @@ bnx2x_check_bull(struct bnx2x_softc *sc)
>         if (valid_bitmap & (1 << MAC_ADDR_VALID) && memcmp(bull->mac,
> sc->old_bulletin.mac, ETH_ALEN))
>                 rte_memcpy(&sc->link_params.mac_addr, bull->mac, ETH_ALEN);
>         if (valid_bitmap & (1 << VLAN_VALID))
> -               rte_memcpy(&bull->vlan, &sc->old_bulletin.vlan,
> RTE_VLAN_HLEN);
> +               rte_memcpy(&bull->vlan, &sc->old_bulletin.vlan,
> sizeof(bull->vlan));
>
>         sc->old_bulletin = *bull;
>
> --
> 2.17.1
>
>

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