[dpdk-dev] [PATCH 21/53] net/sfc/base: optimize credits overflow check

[Andrew Rybchenko]

From: Andrew Rybchenko <andrew.rybche...@oktetlabs.ru>

Apply check against firmware maximum just before pushing.
However, it does not save from overflow inside firmware,
if firmware still have some credits.

Signed-off-by: Andrew Rybchenko <arybche...@solarflare.com>
---
 drivers/net/sfc/base/ef10_ev.c |  4 +---
 drivers/net/sfc/base/ef10_rx.c | 18 +++++++++++-------
 2 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/drivers/net/sfc/base/ef10_ev.c b/drivers/net/sfc/base/ef10_ev.c
index 9ed22f8..946efeb 100644
--- a/drivers/net/sfc/base/ef10_ev.c
+++ b/drivers/net/sfc/base/ef10_ev.c
@@ -803,9 +803,7 @@ ef10_ev_rx_packed_stream(
 
        if (new_buffer) {
                flags |= EFX_PKT_PACKED_STREAM_NEW_BUFFER;
-               if (eersp->eers_rx_packed_stream_credits <
-                   EFX_RX_PACKED_STREAM_MAX_CREDITS)
-                       eersp->eers_rx_packed_stream_credits++;
+               eersp->eers_rx_packed_stream_credits++;
                eersp->eers_rx_read_ptr++;
        }
        current_id = eersp->eers_rx_read_ptr & eersp->eers_rx_mask;
diff --git a/drivers/net/sfc/base/ef10_rx.c b/drivers/net/sfc/base/ef10_rx.c
index 69ebc2d..6a301c1 100644
--- a/drivers/net/sfc/base/ef10_rx.c
+++ b/drivers/net/sfc/base/ef10_rx.c
@@ -786,18 +786,25 @@ ef10_rx_qpush_ps_credits(
        efx_dword_t dword;
        efx_evq_rxq_state_t *rxq_state =
                &erp->er_eep->ee_rxq_state[erp->er_label];
+       uint32_t credits;
 
        EFSYS_ASSERT(rxq_state->eers_rx_packed_stream);
 
        if (rxq_state->eers_rx_packed_stream_credits == 0)
                return;
 
+       /*
+        * It is a bug if we think that FW has utilized more
+        * credits than it is allowed to have (maximum). However,
+        * make sure that we do not credit more than maximum anyway.
+        */
+       credits = MIN(rxq_state->eers_rx_packed_stream_credits,
+           EFX_RX_PACKED_STREAM_MAX_CREDITS);
        EFX_POPULATE_DWORD_3(dword,
            ERF_DZ_RX_DESC_MAGIC_DOORBELL, 1,
            ERF_DZ_RX_DESC_MAGIC_CMD,
            ERE_DZ_RX_DESC_MAGIC_CMD_PS_CREDITS,
-           ERF_DZ_RX_DESC_MAGIC_DATA,
-           rxq_state->eers_rx_packed_stream_credits);
+           ERF_DZ_RX_DESC_MAGIC_DATA, credits);
        EFX_BAR_TBL_WRITED(enp, ER_DZ_RX_DESC_UPD_REG,
            erp->er_index, &dword, B_FALSE);
 
@@ -849,11 +856,8 @@ ef10_rx_qps_packet_info(
        EFSYS_ASSERT3U(current_offset + *lengthp, <, *next_offsetp);
 
        if ((*next_offsetp ^ current_offset) &
-           EFX_RX_PACKED_STREAM_MEM_PER_CREDIT) {
-               if (rxq_state->eers_rx_packed_stream_credits <
-                   EFX_RX_PACKED_STREAM_MAX_CREDITS)
-                       rxq_state->eers_rx_packed_stream_credits++;
-       }
+           EFX_RX_PACKED_STREAM_MEM_PER_CREDIT)
+               rxq_state->eers_rx_packed_stream_credits++;
 
        return (pkt_start);
 }
-- 
2.7.4