Re: [PATCH net-next v3 08/13] bnxt: use snapshot in bnxt_cfg_rx_mode

[Stanislav Fomichev <stfomichev@gmail.com>]

On 03/23, Michael Chan wrote:
> On Thu, Mar 19, 2026 at 6:25 PM Stanislav Fomichev <sdf@fomichev.me> wrote:
> >
> > With the introduction of ndo_set_rx_mode_async (as discussed in [0])
> > we can call bnxt_cfg_rx_mode directly. Convert bnxt_cfg_rx_mode to
> > use uc/mc snapshots and move its call in bnxt_sp_task to the
> > section that resets BNXT_STATE_IN_SP_TASK. Switch to direct call in
> > bnxt_set_rx_mode.
> >
> > 0: https://lore.kernel.org/netdev/CACKFLi=5vj8hPqEUKDd8RTw3au5G+zRgQEqjF+6NZnyoNm90KA@mail.gmail.com/
> >
> > Cc: Michael Chan <michael.chan@broadcom.com>
> > Cc: Pavan Chebbi <pavan.chebbi@broadcom.com>
> > Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
> > ---
> >  drivers/net/ethernet/broadcom/bnxt/bnxt.c | 26 ++++++++++++++---------
> >  1 file changed, 16 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> > index 225217b32e4b..12265bd7fda4 100644
> > --- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> > +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> > @@ -11039,7 +11039,8 @@ static int bnxt_setup_nitroa0_vnic(struct bnxt *bp)
> >         return rc;
> >  }
> >
> > -static int bnxt_cfg_rx_mode(struct bnxt *);
> > +static int bnxt_cfg_rx_mode(struct bnxt *, struct netdev_hw_addr_list *,
> > +                           struct netdev_hw_addr_list *);
> >  static bool bnxt_mc_list_updated(struct bnxt *, u32 *,
> >                                  const struct netdev_hw_addr_list *);
> >
> > @@ -11135,7 +11136,7 @@ static int bnxt_init_chip(struct bnxt *bp, bool irq_re_init)
> >                 vnic->rx_mask |= mask;
> >         }
> >
> > -       rc = bnxt_cfg_rx_mode(bp);
> > +       rc = bnxt_cfg_rx_mode(bp, &bp->dev->uc, &bp->dev->mc);
> >         if (rc)
> >                 goto err_out;
> >
> > @@ -13610,11 +13611,12 @@ static void bnxt_set_rx_mode(struct net_device *dev,
> >         if (mask != vnic->rx_mask || uc_update || mc_update) {
> >                 vnic->rx_mask = mask;
> >
> > -               bnxt_queue_sp_work(bp, BNXT_RX_MASK_SP_EVENT);
> > +               bnxt_cfg_rx_mode(bp, uc, mc);
> >         }
> >  }
> >
> > -static int bnxt_cfg_rx_mode(struct bnxt *bp)
> > +static int bnxt_cfg_rx_mode(struct bnxt *bp, struct netdev_hw_addr_list *uc,
> > +                           struct netdev_hw_addr_list *mc)
> >  {
> >         struct net_device *dev = bp->dev;
> >         struct bnxt_vnic_info *vnic = &bp->vnic_info[BNXT_VNIC_DEFAULT];
> > @@ -13623,7 +13625,7 @@ static int bnxt_cfg_rx_mode(struct bnxt *bp)
> >         bool uc_update;
> >
> >         netif_addr_lock_bh(dev);
> > -       uc_update = bnxt_uc_list_updated(bp, &dev->uc);
> > +       uc_update = bnxt_uc_list_updated(bp, uc);
> 
> Will the uc list snapshot change between bnxt_set_rx_mode() and
> bnxt_cfg_rx_mode() with the direct call now?  In the original deferred
> update implementation, the uc list can change and that's why we check
> in both functions.

The snapshot is gonna be the same for bnxt_set_rx_mode->bnxt_cfg_rx_mode path.

So you're saying that it's ok to remove the one in bnxt_cfg_rx_mode
because it's called either from bnxt_set_rx_mode (with a new list) or,
explicitly, via the BNXT_RX_MASK_SP_EVENT retry mechanism (where we know
that we need to redo the updates anyway)?

This makes me wonder whether I need to push the retrying mechanism to
the core stack... Right now, if some of the allocations in wq handler
fail, we just give up, maybe I should handle it better. And I can plug
the signal from the driver (make ndo_set_rx_mode_async return int)
in the same retry mechanism.