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Date: Mon, 20 Sep 2021 02:51:52 -0400
From: Michael Chan <michael.chan@...adcom.com>
To: davem@...emloft.net
Cc: netdev@...r.kernel.org, kuba@...nel.org, gospo@...adcom.com
Subject: [PATCH net] bnxt_en: Fix TX timeout when TX ring size is set to the smallest
The smallest TX ring size we support must fit a TX SKB with MAX_SKB_FRAGS
+ 1. Because the first TX BD for a packet is always a long TX BD, we
need an extra TX BD to fit this packet. Define BNXT_MIN_TX_DESC_CNT with
this value to make this more clear. The current code uses a minimum
that is off by 1. Fix it using this constant.
The tx_wake_thresh to determine when to wake up the TX queue is half the
ring size but we must have at least BNXT_MIN_TX_DESC_CNT for the next
packet which may have maximum fragments. So the comparison of the
available TX BDs with tx_wake_thresh should be >= instead of > in the
current code. Otherwise, at the smallest ring size, we will never wake
up the TX queue and will cause TX timeout.
Fixes: c0c050c58d84 ("bnxt_en: New Broadcom ethernet driver.")
Reviewed-by: Pavan Chebbi <pavan.chebbi@...adcom.com>
Signed-off-by: Michael Chan <michael.chan@...adocm.com>
---
drivers/net/ethernet/broadcom/bnxt/bnxt.c | 8 ++++----
drivers/net/ethernet/broadcom/bnxt/bnxt.h | 5 +++++
drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c | 2 +-
3 files changed, 10 insertions(+), 5 deletions(-)
diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 037767b370d5..62f84cc91e4d 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -391,7 +391,7 @@ static bool bnxt_txr_netif_try_stop_queue(struct bnxt *bp,
* netif_tx_queue_stopped().
*/
smp_mb();
- if (bnxt_tx_avail(bp, txr) > bp->tx_wake_thresh) {
+ if (bnxt_tx_avail(bp, txr) >= bp->tx_wake_thresh) {
netif_tx_wake_queue(txq);
return false;
}
@@ -764,7 +764,7 @@ static void bnxt_tx_int(struct bnxt *bp, struct bnxt_napi *bnapi, int nr_pkts)
smp_mb();
if (unlikely(netif_tx_queue_stopped(txq)) &&
- bnxt_tx_avail(bp, txr) > bp->tx_wake_thresh &&
+ bnxt_tx_avail(bp, txr) >= bp->tx_wake_thresh &&
READ_ONCE(txr->dev_state) != BNXT_DEV_STATE_CLOSING)
netif_tx_wake_queue(txq);
}
@@ -2416,7 +2416,7 @@ static int __bnxt_poll_work(struct bnxt *bp, struct bnxt_cp_ring_info *cpr,
if (TX_CMP_TYPE(txcmp) == CMP_TYPE_TX_L2_CMP) {
tx_pkts++;
/* return full budget so NAPI will complete. */
- if (unlikely(tx_pkts > bp->tx_wake_thresh)) {
+ if (unlikely(tx_pkts >= bp->tx_wake_thresh)) {
rx_pkts = budget;
raw_cons = NEXT_RAW_CMP(raw_cons);
if (budget)
@@ -3640,7 +3640,7 @@ static int bnxt_init_tx_rings(struct bnxt *bp)
u16 i;
bp->tx_wake_thresh = max_t(int, bp->tx_ring_size / 2,
- MAX_SKB_FRAGS + 1);
+ BNXT_MIN_TX_DESC_CNT);
for (i = 0; i < bp->tx_nr_rings; i++) {
struct bnxt_tx_ring_info *txr = &bp->tx_ring[i];
diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.h b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
index ec046e7a2484..19fe6478e9b4 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.h
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
@@ -629,6 +629,11 @@ struct nqe_cn {
#define BNXT_MAX_RX_JUM_DESC_CNT (RX_DESC_CNT * MAX_RX_AGG_PAGES - 1)
#define BNXT_MAX_TX_DESC_CNT (TX_DESC_CNT * MAX_TX_PAGES - 1)
+/* Minimum TX BDs for a TX packet with MAX_SKB_FRAGS + 1. We need one extra
+ * BD because the first TX BD is always a long BD.
+ */
+#define BNXT_MIN_TX_DESC_CNT (MAX_SKB_FRAGS + 2)
+
#define RX_RING(x) (((x) & ~(RX_DESC_CNT - 1)) >> (BNXT_PAGE_SHIFT - 4))
#define RX_IDX(x) ((x) & (RX_DESC_CNT - 1))
diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c b/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
index b056e3c29bbd..7260910e75fb 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
@@ -798,7 +798,7 @@ static int bnxt_set_ringparam(struct net_device *dev,
if ((ering->rx_pending > BNXT_MAX_RX_DESC_CNT) ||
(ering->tx_pending > BNXT_MAX_TX_DESC_CNT) ||
- (ering->tx_pending <= MAX_SKB_FRAGS))
+ (ering->tx_pending < BNXT_MIN_TX_DESC_CNT))
return -EINVAL;
if (netif_running(dev))
--
2.18.1
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