Merge branch 'bnxt_en-fix-max_skb_frags-30'

Michael Chan says:

====================
bnxt_en: Fix MAX_SKB_FRAGS > 30

The driver was written with the assumption that MAX_SKB_FRAGS could
not exceed what the NIC can support.  About 2 years ago,
CONFIG_MAX_SKB_FRAGS was added.  The value can exceed what the NIC
can support and it may cause TX timeout.  These 2 patches will fix
the issue.
====================

Link: https://patch.msgid.link/20250321211639.3812992-1-michael.chan@broadcom.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: kuba-moo

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 */
@@ -564,7 +575,7 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev)
 					TX_BD_FLAGS_LHINT_512_AND_SMALLER |
 					TX_BD_FLAGS_COAL_NOW |
 					TX_BD_FLAGS_PACKET_END |
-					(2 << TX_BD_FLAGS_BD_CNT_SHIFT));
+					TX_BD_CNT(2));
 
 		if (skb->ip_summed == CHECKSUM_PARTIAL)
 			tx_push1->tx_bd_hsize_lflags =
@@ -639,7 +650,7 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev)
 
 	dma_unmap_addr_set(tx_buf, mapping, mapping);
 	flags = (len << TX_BD_LEN_SHIFT) | TX_BD_TYPE_LONG_TX_BD |
-		((last_frag + 2) << TX_BD_FLAGS_BD_CNT_SHIFT);
+		TX_BD_CNT(last_frag + 2);
 
 	txbd->tx_bd_haddr = cpu_to_le64(mapping);
 	txbd->tx_bd_opaque = SET_TX_OPAQUE(bp, txr, prod, 2 + last_frag);

drivers/net/ethernet/broadcom/bnxt/bnxt.h

@@ -82,6 +82,12 @@ struct tx_bd {
 #define TX_OPAQUE_PROD(bp, opq)	((TX_OPAQUE_IDX(opq) + TX_OPAQUE_BDS(opq)) &\
 				 (bp)->tx_ring_mask)
 
+#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)

drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c

@@ -48,8 +48,7 @@ struct bnxt_sw_tx_bd *bnxt_xmit_bd(struct bnxt *bp,
 		tx_buf->page = virt_to_head_page(xdp->data);
 
 	txbd = &txr->tx_desc_ring[TX_RING(bp, prod)][TX_IDX(prod)];
-	flags = (len << TX_BD_LEN_SHIFT) |
-		((num_frags + 1) << TX_BD_FLAGS_BD_CNT_SHIFT) |
+	flags = (len << TX_BD_LEN_SHIFT) | TX_BD_CNT(num_frags + 1) |
 		bnxt_lhint_arr[len >> 9];
 	txbd->tx_bd_len_flags_type = cpu_to_le32(flags);
 	txbd->tx_bd_opaque = SET_TX_OPAQUE(bp, txr, prod, 1 + num_frags);