bnxt_en: Linearize TX SKB if the fragments exceed the max

If skb_shinfo(skb)->nr_frags excceds what the chip can support,
linearize the SKB and warn once to let the user know.
net.core.max_skb_frags can be lowered, for example, to avoid the
issue.

Fixes: 3948b05950fd ("net: introduce a config option to tweak MAX_SKB_FRAGS")
Reviewed-by: Somnath Kotur <somnath.kotur@broadcom.com>
Reviewed-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Reviewed-by: Andy Gospodarek <andrew.gospodarek@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250321211639.3812992-3-michael.chan@broadcom.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 158e9789c1f46845760a121223c7f422b4febdc4..2cd79b59cf0022986bd9916426c1f457d3fa94be 100644 (file)
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -485,6 +485,17 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev)
        txr = &bp->tx_ring[bp->tx_ring_map[i]];
        prod = txr->tx_prod;
 
+#if (MAX_SKB_FRAGS > TX_MAX_FRAGS)
+       if (skb_shinfo(skb)->nr_frags > TX_MAX_FRAGS) {
+               netdev_warn_once(dev, "SKB has too many (%d) fragments, max supported is %d.  SKB will be linearized.\n",
+                                skb_shinfo(skb)->nr_frags, TX_MAX_FRAGS);
+               if (skb_linearize(skb)) {
+                       dev_kfree_skb_any(skb);
+                       dev_core_stats_tx_dropped_inc(dev);
+                       return NETDEV_TX_OK;
+               }
+       }
+#endif
        free_size = bnxt_tx_avail(bp, txr);
        if (unlikely(free_size < skb_shinfo(skb)->nr_frags + 2)) {
                /* We must have raced with NAPI cleanup */

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.h b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
index 3b4a044db73e3f14cee49a9cf92cd1d9195439d2..d621fb621f30c7cc9784efcdeeca562e205b99c3 100644 (file)
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.h
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
@@ -84,6 +84,10 @@ struct tx_bd {
 
 #define TX_BD_CNT(n)   (((n) << TX_BD_FLAGS_BD_CNT_SHIFT) & TX_BD_FLAGS_BD_CNT)
 
+#define TX_MAX_BD_CNT  32
+
+#define TX_MAX_FRAGS           (TX_MAX_BD_CNT - 2)
+
 struct tx_bd_ext {
        __le32 tx_bd_hsize_lflags;
        #define TX_BD_FLAGS_TCP_UDP_CHKSUM                      (1 << 0)