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

  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.
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(-)
  

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
>
>
  

From: Stanisław Kardach [mailto:kda@semihalf.com] 
Sent: Wednesday, 28 December 2022 17.14
> 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?

Absolutely. It would also have prevented the bug to begin with.
But in order to keep the changes minimal, I kept the rte_memcpy().

> > 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));

As Stanisław mentioned, this might as well be:

        if (valid_bitmap & (1 << VLAN_VALID))
-               rte_memcpy(&bull->vlan, &sc->old_bulletin.vlan, RTE_VLAN_HLEN);
+               bull->vlan = sc->old_bulletin.vlan;

> > 
> >         sc->old_bulletin = *bull;
> > 
> > -- 
> > 2.17.1
  

On Wed, 28 Dec 2022 17:38:56 +0100
Morten Brørup <mb@smartsharesystems.com> wrote:

> From: Stanisław Kardach [mailto:kda@semihalf.com] 
> Sent: Wednesday, 28 December 2022 17.14
> > 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?  
> 
> Absolutely. It would also have prevented the bug to begin with.
> But in order to keep the changes minimal, I kept the rte_memcpy().

For small fixed values compiler can optimize memcpy into one instruction.
Not so with current rte_memcpy
  

> From: Stephen Hemminger [mailto:stephen@networkplumber.org]
> Sent: Wednesday, 28 December 2022 18.03
> 
> On Wed, 28 Dec 2022 17:38:56 +0100
> Morten Brørup <mb@smartsharesystems.com> wrote:
> 
> > From: Stanisław Kardach [mailto:kda@semihalf.com]
> > Sent: Wednesday, 28 December 2022 17.14
> > > 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?
> >
> > Absolutely. It would also have prevented the bug to begin with.
> > But in order to keep the changes minimal, I kept the rte_memcpy().
> 
> For small fixed values compiler can optimize memcpy into one
> instruction.
> Not so with current rte_memcpy

Good point, Stephen.

I took another look at it, and the two byte rte_memcpy() is only used in a slow path function, so no need to optimize further.

If the maintainers disagree, and want to optimize anyway, here's a proposal:

/* check the mac address and VLAN and allocate memory if valid */
if (valid_bitmap & (1 << MAC_ADDR_VALID) && !rte_is_same_ether_addr(
		(const struct rte_ether_addr *)&bull->mac,
		(const struct rte_ether_addr *)&sc->old_bulletin.mac))
	rte_ether_addr_copy((const struct rte_ether_addr *)&bull->mac,
			(struct rte_ether_addr *)&sc->link_params.mac_addr);
if (valid_bitmap & (1 << VLAN_VALID))
	bull->vlan = sc->old_bulletin.vlan;
  

Hello bnx2x maintainers,

On Wed, Dec 28, 2022 at 6:37 PM Morten Brørup <mb@smartsharesystems.com> wrote:
>
> > From: Stephen Hemminger [mailto:stephen@networkplumber.org]
> > Sent: Wednesday, 28 December 2022 18.03
> >
> > On Wed, 28 Dec 2022 17:38:56 +0100
> > Morten Brørup <mb@smartsharesystems.com> wrote:
> >
> > > From: Stanisław Kardach [mailto:kda@semihalf.com]
> > > Sent: Wednesday, 28 December 2022 17.14
> > > > 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?
> > >
> > > Absolutely. It would also have prevented the bug to begin with.
> > > But in order to keep the changes minimal, I kept the rte_memcpy().
> >
> > For small fixed values compiler can optimize memcpy into one
> > instruction.
> > Not so with current rte_memcpy
>
> Good point, Stephen.
>
> I took another look at it, and the two byte rte_memcpy() is only used in a slow path function, so no need to optimize further.
>
> If the maintainers disagree, and want to optimize anyway, here's a proposal:
>
> /* check the mac address and VLAN and allocate memory if valid */
> if (valid_bitmap & (1 << MAC_ADDR_VALID) && !rte_is_same_ether_addr(
>                 (const struct rte_ether_addr *)&bull->mac,
>                 (const struct rte_ether_addr *)&sc->old_bulletin.mac))
>         rte_ether_addr_copy((const struct rte_ether_addr *)&bull->mac,
>                         (struct rte_ether_addr *)&sc->link_params.mac_addr);
> if (valid_bitmap & (1 << VLAN_VALID))
>         bull->vlan = sc->old_bulletin.vlan;
>

Please review/advise.
Thanks.