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

[Andrew Rybchenko <arybchenko@solarflare.com>]

From: Andrew Rybchenko <Andrew.Rybchenko@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 <arybchenko@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