bnxt: use READ_ONCE/WRITE_ONCE for ring indexes

Eric points out that we should make sure that ring index updates
are wrapped in the appropriate READ_ONCE/WRITE_ONCE macros.

Suggested-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index f7602d8..92289ab 100644 (file)
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -472,7 +472,7 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev)
                prod = NEXT_TX(prod);
                tx_push->doorbell =
                        cpu_to_le32(DB_KEY_TX_PUSH | DB_LONG_TX_PUSH | prod);
-               txr->tx_prod = prod;
+               WRITE_ONCE(txr->tx_prod, prod);
 
                tx_buf->is_push = 1;
                netdev_tx_sent_queue(txq, skb->len);
@@ -583,7 +583,7 @@ normal_tx:
        wmb();
 
        prod = NEXT_TX(prod);
-       txr->tx_prod = prod;
+       WRITE_ONCE(txr->tx_prod, prod);
 
        if (!netdev_xmit_more() || netif_xmit_stopped(txq))
                bnxt_txr_db_kick(bp, txr, prod);
@@ -688,7 +688,7 @@ next_tx_int:
                dev_kfree_skb_any(skb);
        }
 
-       txr->tx_cons = cons;
+       WRITE_ONCE(txr->tx_cons, cons);
 
        __netif_txq_completed_wake(txq, nr_pkts, tx_bytes,
                                   bnxt_tx_avail(bp, txr), bp->tx_wake_thresh,

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.h b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
index 18cac98..080e734 100644 (file)
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.h
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
@@ -2231,13 +2231,12 @@ struct bnxt {
 #define SFF_MODULE_ID_QSFP28                   0x11
 #define BNXT_MAX_PHY_I2C_RESP_SIZE             64
 
-static inline u32 bnxt_tx_avail(struct bnxt *bp, struct bnxt_tx_ring_info *txr)
+static inline u32 bnxt_tx_avail(struct bnxt *bp,
+                               const struct bnxt_tx_ring_info *txr)
 {
-       /* Tell compiler to fetch tx indices from memory. */
-       barrier();
+       u32 used = READ_ONCE(txr->tx_prod) - READ_ONCE(txr->tx_cons);
 
-       return bp->tx_ring_size -
-               ((txr->tx_prod - txr->tx_cons) & bp->tx_ring_mask);
+       return bp->tx_ring_size - (used & bp->tx_ring_mask);
 }
 
 static inline void bnxt_writeq(struct bnxt *bp, u64 val,

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c b/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c
index 5843c93..4efa5fe 100644 (file)
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c
@@ -64,7 +64,7 @@ struct bnxt_sw_tx_bd *bnxt_xmit_bd(struct bnxt *bp,
                int frag_len;
 
                prod = NEXT_TX(prod);
-               txr->tx_prod = prod;
+               WRITE_ONCE(txr->tx_prod, prod);
 
                /* first fill up the first buffer */
                frag_tx_buf = &txr->tx_buf_ring[prod];
@@ -94,7 +94,7 @@ struct bnxt_sw_tx_bd *bnxt_xmit_bd(struct bnxt *bp,
        /* Sync TX BD */
        wmb();
        prod = NEXT_TX(prod);
-       txr->tx_prod = prod;
+       WRITE_ONCE(txr->tx_prod, prod);
 
        return tx_buf;
 }
@@ -161,7 +161,7 @@ void bnxt_tx_int_xdp(struct bnxt *bp, struct bnxt_napi *bnapi, int nr_pkts)
                }
                tx_cons = NEXT_TX(tx_cons);
        }
-       txr->tx_cons = tx_cons;
+       WRITE_ONCE(txr->tx_cons, tx_cons);
        if (rx_doorbell_needed) {
                tx_buf = &txr->tx_buf_ring[last_tx_cons];
                bnxt_db_write(bp, &rxr->rx_db, tx_buf->rx_prod);