Re: [PATCH net-next 12/16] idpf: implement XDP_SETUP_PROG in ndo_bpf for splitq

Maciej Fijalkowski
2025-03-19T16:23:59Z

On Mon, Mar 17, 2025 at 03:58:12PM +0100, Alexander Lobakin wrote:
> From: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
> Date: Fri, 7 Mar 2025 15:16:48 +0100
>
> > On Wed, Mar 05, 2025 at 05:21:28PM +0100, Alexander Lobakin wrote:
> >> From: Michal Kubiak <michal.kubiak@intel.com>
> >>
> >> Implement loading/removing XDP program using .ndo_bpf callback
> >> in the split queue mode. Reconfigure and restart the queues if needed
> >> (!!old_prog != !!new_prog), otherwise, just update the pointers.
> >>
> >> Signed-off-by: Michal Kubiak <michal.kubiak@intel.com>
> >> Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
> >> ---
> >> drivers/net/ethernet/intel/idpf/idpf_txrx.h | 4 +-
> >> drivers/net/ethernet/intel/idpf/xdp.h | 7 ++
> >> drivers/net/ethernet/intel/idpf/idpf_lib.c | 1 +
> >> drivers/net/ethernet/intel/idpf/idpf_txrx.c | 4 +
> >> drivers/net/ethernet/intel/idpf/xdp.c | 114 ++++++++++++++++++++
> >> 5 files changed, 129 insertions(+), 1 deletion(-)
> >>
> >
> > (...)
> >
> >> +
> >> +/**
> >> + * idpf_xdp_setup_prog - handle XDP program install/remove requests
> >> + * @vport: vport to configure
> >> + * @xdp: request data (program, extack)
> >> + *
> >> + * Return: 0 on success, -errno on failure.
> >> + */
> >> +static int
> >> +idpf_xdp_setup_prog(struct idpf_vport *vport, const struct netdev_bpf *xdp)
> >> +{
> >> + const struct idpf_netdev_priv *np = netdev_priv(vport->netdev);
> >> + struct bpf_prog *old, *prog = xdp->prog;
> >> + struct idpf_vport_config *cfg;
> >> + int ret;
> >> +
> >> + cfg = vport->adapter->vport_config[vport->idx];
> >> + if (!vport->num_xdp_txq && vport->num_txq == cfg->max_q.max_txq) {
> >> + NL_SET_ERR_MSG_MOD(xdp->extack,
> >> + "No Tx queues available for XDP, please decrease the number of regular SQs");
> >> + return -ENOSPC;
> >> + }
> >> +
> >> + if (test_bit(IDPF_REMOVE_IN_PROG, vport->adapter->flags) ||
> >
> > IN_PROG is a bit unfortunate here as it mixes with 'prog' :P
>
> Authentic idpf dictionary ¯\_(ツ)_/¯
>
> >
> >> + !!vport->xdp_prog == !!prog) {
> >> + if (np->state == __IDPF_VPORT_UP)
> >> + idpf_copy_xdp_prog_to_qs(vport, prog);
> >> +
> >> + old = xchg(&vport->xdp_prog, prog);
> >> + if (old)
> >> + bpf_prog_put(old);
> >> +
> >> + cfg->user_config.xdp_prog = prog;
> >> +
> >> + return 0;
> >> + }
> >> +
> >> + old = cfg->user_config.xdp_prog;
> >> + cfg->user_config.xdp_prog = prog;
> >> +
> >> + ret = idpf_initiate_soft_reset(vport, IDPF_SR_Q_CHANGE);
> >> + if (ret) {
> >> + NL_SET_ERR_MSG_MOD(xdp->extack,
> >> + "Could not reopen the vport after XDP setup");
> >> +
> >> + if (prog)
> >> + bpf_prog_put(prog);
> >
> > aren't you missing this for prog->NULL conversion? you have this for
> > hot-swap case (prog->prog).
>
> This path (soft_reset) handles NULL => prog and prog => NULL. This
> branch in particular handles errors during the soft reset, when we need
> to restore the original prog and put the new one.
>
> What you probably meant is that I don't have bpf_prog_put(old) in case
> everything went well below? Breh =\

yes, best to check with bpftool if there are dangling bpf progs on system
after using few xdp samples, for example.

>
> >
> >> +
> >> + cfg->user_config.xdp_prog = old;
> >> + }
> >> +
> >> + return ret;
> >> +}
>
> Thanks,
> Olek