bnxt_en: Fix TX timeout when TX ring size is set to the smallest

[ Upstream commit 5bed8b0704c9ecccc8f4a2c377d7c8e21090a82e ]

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@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadocm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 26179e437bbfd2617c1835642038fe1d850446d4..cb0c270418a4d1dfb2fa725424d855e73c063350 100644 (file)
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -381,7 +381,7 @@ 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;
        }
@@ -717,7 +717,7 @@ next_tx_int:
        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);
 }
@@ -2300,7 +2300,7 @@ 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)
@@ -3431,7 +3431,7 @@ 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 95d10e7bbb041e2d36e39a86905062c414101e13..92f9f7f5240b623b0a83a50bccb09cd4e1a4f76a 100644 (file)
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.h
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
@@ -611,6 +611,11 @@ 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 1471c9a362388d0004b83e55fdaf750cd3c0f23f..6f9196ff2ac4f56b0c73303ca618b460160f4447 100644 (file)
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
@@ -780,7 +780,7 @@ 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))