Re: [PATCH net-next v10 5/7] r8169: add support and enable rss

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r8169: add support and enable rss

This patch adds support and enables Receive Side Scaling (RSS) for RTL8127.
It configures RSS keys, redirection tables, and introduces support for
parsing RSS-specific RX descriptors.

[ ... ]

[ ... ]

+static inline void rtl8169_rx_csum(struct rtl8169_private *tp,
+				   struct sk_buff *skb,
 				   u32 opts1)
 {
-	u32 status = opts1 & (RxProtoMask | RxCSFailMask);
+	bool csum_ok = false;
+
+	switch (tp->init_rx_desc_type) {
+	case RX_DESC_TYPE_RSS:
+		if (((opts1 & RX_TCPT_DESC_RSS) && !(opts1 & RX_TCPF_DESC_RSS)) ||
+		    ((opts1 & RX_UDPT_DESC_RSS) && !(opts1 & RX_UDPF_DESC_RSS)))
+			csum_ok = true;
+		break;
+	default:
+		u32 status = opts1 & (RxProtoMask | RxCSFailMask);

[Severity: Low]
Will this compile under standard C? Declaring a variable immediately
following a label (default:) is a syntax error in C unless it is wrapped in
a block.

 
-	if (status == RxProtoTCP || status == RxProtoUDP)
+		if (status == RxProtoTCP || status == RxProtoUDP)
+			csum_ok = true;
+		break;
+	}
+
+	if (csum_ok)
 		skb->ip_summed = CHECKSUM_UNNECESSARY;
 	else
 		skb_checksum_none_assert(skb);
 }

[ ... ]

 static bool rtl8169_check_rx_desc_error(struct net_device *dev,
 					struct rtl8169_private *tp,
 					u32 status)
 {
-	if (unlikely(status & RxRES)) {
-		if (status & (RxRWT | RxRUNT))
-			dev->stats.rx_length_errors++;
-		if (status & RxCRC)
-			dev->stats.rx_crc_errors++;
-		return true;
+	switch (tp->init_rx_desc_type) {
+	case RX_DESC_TYPE_RSS:
+		if (unlikely(status & RX_RES_RSS)) {
+			if (status & RX_RUNT_RSS)
+				dev->stats.rx_length_errors++;
+			if (status & RX_CRC_RSS)
+				dev->stats.rx_crc_errors++;

[Severity: Medium]
Can these direct increments to dev->stats cause lost updates?

Now that RSS is enabled, multiple RX queues can trigger NAPI polling
concurrently on different CPUs. If multiple queues receive errored packets
simultaneously, they will race to read-modify-write these global stat
counters.

+			return true;
+		}
+		break;
+	default:
+		if (unlikely(status & RxRES)) {
+			if (status & (RxRWT | RxRUNT))
+				dev->stats.rx_length_errors++;
+			if (status & RxCRC)
+				dev->stats.rx_crc_errors++;
+			return true;
+		}
+		break;
 	}
 	return false;
 }

[ ... ]

[Severity: High]
Does this bypass the drop logic for fatal errors when RSS and RXALL are
both enabled?

If the hardware receives a fatally errored packet while RSS is enabled,
the descriptor type check (tp->init_rx_desc_type == RX_DESC_TYPE_DEFAULT)
prevents the code from taking the goto release_descriptor path. This could
cause the driver to process frames with corrupted length fields or 
uninitialized memory.