Re: [PATCH net-next v2 2/3] bnxt: count packets discarded because of netpoll

bnxt may discard packets if Rx completions are consumed
in an attempt to let netpoll make progress. It should be
exteremely rare in practice but nonetheless such events
should be counted.

Since completion ring memory is allocated dynamically use
a similar scheme to what is done for HW stats to save them.

Report the stats in rx_dropped and per-netdev ethtool
counter. Chances that users care which ring dropped are
very low.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt.c     | 31 ++++++++++++++-----
 drivers/net/ethernet/broadcom/bnxt/bnxt.h     |  2 ++
 .../net/ethernet/broadcom/bnxt/bnxt_ethtool.c |  6 ++++
 3 files changed, 32 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index d39449e7b236..d12a9052388f 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -2003,6 +2003,7 @@ static int bnxt_force_rx_discard(struct bnxt *bp,
        struct rx_cmp *rxcmp;
        u16 cp_cons;
        u8 cmp_type;
+       int ret;

        cp_cons = RING_CMP(tmp_raw_cons);
        rxcmp = (struct rx_cmp *)

@@ -2031,7 +2032,10 @@ static int bnxt_force_rx_discard(struct bnxt *bp,
                tpa_end1->rx_tpa_end_cmp_errors_v2 |=
                        cpu_to_le32(RX_TPA_END_CMP_ERRORS);
        }
-       return bnxt_rx_pkt(bp, cpr, raw_cons, event);
+       ret = bnxt_rx_pkt(bp, cpr, raw_cons, event);
+       if (ret != -EBUSY)
+               cpr->sw_stats.rx.rx_netpoll_discards += 1;