| Message ID | 20230615113326.347770-1-maciej.fijalkowski@intel.com (mailing list archive) |
|---|---|
| State | Awaiting Upstream |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [v3,iwl-next] ice: allow hot-swapping XDP programs | expand |
Maciej Fijalkowski <maciej.fijalkowski@intel.com> writes: > Currently ice driver's .ndo_bpf callback brings interface down and up > independently of XDP resources' presence. This is only needed when > either these resources have to be configured or removed. It means that > if one is switching XDP programs on-the-fly with running traffic, > packets will be dropped. > > To avoid this, compare early on ice_xdp_setup_prog() state of incoming > bpf_prog pointer vs the bpf_prog pointer that is already assigned to > VSI. Do the swap in case VSI has bpf_prog and incoming one are non-NULL. > > Lastly, while at it, put old bpf_prog *after* the update of Rx ring's > bpf_prog pointer. In theory previous code could expose us to a state > where Rx ring's bpf_prog would still be referring to old_prog that got > released with earlier bpf_prog_put(). > > Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
From: Maciej Fijalkowski <maciej.fijalkowski@intel.com> Date: Thu, 15 Jun 2023 13:33:26 +0200 > Currently ice driver's .ndo_bpf callback brings interface down and up > independently of XDP resources' presence. This is only needed when > either these resources have to be configured or removed. It means that > if one is switching XDP programs on-the-fly with running traffic, > packets will be dropped. > > To avoid this, compare early on ice_xdp_setup_prog() state of incoming > bpf_prog pointer vs the bpf_prog pointer that is already assigned to > VSI. Do the swap in case VSI has bpf_prog and incoming one are non-NULL. > > Lastly, while at it, put old bpf_prog *after* the update of Rx ring's > bpf_prog pointer. In theory previous code could expose us to a state > where Rx ring's bpf_prog would still be referring to old_prog that got > released with earlier bpf_prog_put(). > > Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com> Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com> Good stuff, much missing previously. [...] Thanks, Olek
>-----Original Message----- >From: Intel-wired-lan <intel-wired-lan-bounces@osuosl.org> On Behalf Of >Fijalkowski, Maciej >Sent: 15 June 2023 17:03 >To: intel-wired-lan@lists.osuosl.org >Cc: toke@kernel.org; netdev@vger.kernel.org; Nguyen, Anthony L ><anthony.l.nguyen@intel.com>; Karlsson, Magnus ><magnus.karlsson@intel.com>; fred@cloudflare.com >Subject: [Intel-wired-lan] [PATCH v3 iwl-next] ice: allow hot-swapping XDP >programs > >Currently ice driver's .ndo_bpf callback brings interface down and up >independently of XDP resources' presence. This is only needed when either >these resources have to be configured or removed. It means that if one is >switching XDP programs on-the-fly with running traffic, packets will be >dropped. > >To avoid this, compare early on ice_xdp_setup_prog() state of incoming >bpf_prog pointer vs the bpf_prog pointer that is already assigned to VSI. Do >the swap in case VSI has bpf_prog and incoming one are non-NULL. > >Lastly, while at it, put old bpf_prog *after* the update of Rx ring's bpf_prog >pointer. In theory previous code could expose us to a state where Rx ring's >bpf_prog would still be referring to old_prog that got released with earlier >bpf_prog_put(). > >Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com> >--- > >v2->v3: >- move bpf_prog_put() after ice_rx_ring::xdp_prog update [Toke, Olek] >v1->v2: >- fix missing brace (sigh) > > drivers/net/ethernet/intel/ice/ice_main.c | 19 +++++++++---------- > 1 file changed, 9 insertions(+), 10 deletions(-) > Tested-by: Chandan Kumar Rout <chandanx.rout@intel.com> (A Contingent Worker at Intel)
diff --git a/drivers/net/ethernet/intel/ice/ice_main.c b/drivers/net/ethernet/intel/ice/ice_main.c index 62e91512aeab..a7c76fded603 100644 --- a/drivers/net/ethernet/intel/ice/ice_main.c +++ b/drivers/net/ethernet/intel/ice/ice_main.c @@ -2633,11 +2633,11 @@ static void ice_vsi_assign_bpf_prog(struct ice_vsi *vsi, struct bpf_prog *prog) int i; old_prog = xchg(&vsi->xdp_prog, prog); - if (old_prog) - bpf_prog_put(old_prog); - ice_for_each_rxq(vsi, i) WRITE_ONCE(vsi->rx_rings[i]->xdp_prog, vsi->xdp_prog); + + if (old_prog) + bpf_prog_put(old_prog); } /** @@ -2922,6 +2922,12 @@ ice_xdp_setup_prog(struct ice_vsi *vsi, struct bpf_prog *prog, } } + /* hot swap progs and avoid toggling link */ + if (ice_is_xdp_ena_vsi(vsi) == !!prog) { + ice_vsi_assign_bpf_prog(vsi, prog); + return 0; + } + /* need to stop netdev while setting up the program for Rx rings */ if (if_running && !test_and_set_bit(ICE_VSI_DOWN, vsi->state)) { ret = ice_down(vsi); @@ -2954,13 +2960,6 @@ ice_xdp_setup_prog(struct ice_vsi *vsi, struct bpf_prog *prog, xdp_ring_err = ice_realloc_zc_buf(vsi, false); if (xdp_ring_err) NL_SET_ERR_MSG_MOD(extack, "Freeing XDP Rx resources failed"); - } else { - /* safe to call even when prog == vsi->xdp_prog as - * dev_xdp_install in net/core/dev.c incremented prog's - * refcount so corresponding bpf_prog_put won't cause - * underflow - */ - ice_vsi_assign_bpf_prog(vsi, prog); } if (if_running)
Currently ice driver's .ndo_bpf callback brings interface down and up independently of XDP resources' presence. This is only needed when either these resources have to be configured or removed. It means that if one is switching XDP programs on-the-fly with running traffic, packets will be dropped. To avoid this, compare early on ice_xdp_setup_prog() state of incoming bpf_prog pointer vs the bpf_prog pointer that is already assigned to VSI. Do the swap in case VSI has bpf_prog and incoming one are non-NULL. Lastly, while at it, put old bpf_prog *after* the update of Rx ring's bpf_prog pointer. In theory previous code could expose us to a state where Rx ring's bpf_prog would still be referring to old_prog that got released with earlier bpf_prog_put(). Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com> --- v2->v3: - move bpf_prog_put() after ice_rx_ring::xdp_prog update [Toke, Olek] v1->v2: - fix missing brace (sigh) drivers/net/ethernet/intel/ice/ice_main.c | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-)