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

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[ 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: c0c050c58d ("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>
This commit is contained in:
Michael Chan 2021-09-20 02:51:52 -04:00 committed by Greg Kroah-Hartman
parent d5afe3cf52
commit 1365a0dc55
3 changed files with 10 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
drivers/net/ethernet/broadcom/bnxt/bnxt.c
View File

@ -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 @@ 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);
}
@ -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];

5
drivers/net/ethernet/broadcom/bnxt/bnxt.h
View File

@ -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))

2
drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
View File

@ -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))