[PATCH net 07/14] can: rockchip_canfd: serialize TX state and command writes

@@ -921,6 +921,7 @@ static int rkcanfd_probe(struct platform_device *pdev)
 	priv->can.do_set_mode = rkcanfd_set_mode;
 	priv->can.do_get_berr_counter = rkcanfd_get_berr_counter;
 	priv->ndev = ndev;
+	spin_lock_init(&priv->tx_lock);
 
 	match = device_get_match_data(&pdev->dev);
 	if (match) {

@@ -100,14 +100,25 @@ static int rkcanfd_rxstx_filter(struct rkcanfd_priv *priv,
 	const struct canfd_frame *cfd_nominal;
 	const struct sk_buff *skb;
 	unsigned int tx_tail;
+	unsigned long flags;
+
+	spin_lock_irqsave(&priv->tx_lock, flags);
+
+	if (!rkcanfd_get_tx_pending(priv))
+		goto out_unlock;
 
 	tx_tail = rkcanfd_get_tx_tail(priv);
 	skb = priv->can.echo_skb[tx_tail];
 	if (!skb) {
+		const unsigned int tx_head_unmasked = priv->tx_head;
+		const unsigned int tx_tail_unmasked = priv->tx_tail;
+
+		spin_unlock_irqrestore(&priv->tx_lock, flags);
+
 		netdev_err(priv->ndev,
 			   "%s: echo_skb[%u]=NULL tx_head=0x%08x tx_tail=0x%08x\n",
 			   __func__, tx_tail,
-			   priv->tx_head, priv->tx_tail);
+			   tx_head_unmasked, tx_tail_unmasked);
 
 		return -ENOMSG;
 	}

@@ -123,17 +134,18 @@ static int rkcanfd_rxstx_filter(struct rkcanfd_priv *priv,
 		rkcanfd_handle_tx_done_one(priv, ts, &frame_len);
 
 		WRITE_ONCE(priv->tx_tail, priv->tx_tail + 1);
+		*tx_done = true;
+
+		spin_unlock_irqrestore(&priv->tx_lock, flags);
 		netif_subqueue_completed_wake(priv->ndev, 0, 1, frame_len,
 					      rkcanfd_get_effective_tx_free(priv),
 					      RKCANFD_TX_START_THRESHOLD);
 
-		*tx_done = true;
-
 		return 0;
 	}
 
 	if (!(priv->devtype_data.quirks & RKCANFD_QUIRK_RK3568_ERRATUM_6))
-		return 0;
+		goto out_unlock;
 
 	/* Erratum 6: Extended frames may be send as standard frames.
 	 *

@@ -143,7 +155,7 @@ static int rkcanfd_rxstx_filter(struct rkcanfd_priv *priv,
 	 */
 	if (!(cfd_nominal->can_id & CAN_EFF_FLAG) ||
 	    (cfd_rx->can_id & CAN_EFF_FLAG))
-		return 0;
+		goto out_unlock;
 
 	/* Not affected if:
 	 * - standard part and RTR flag of the TX'ed frame

@@ -151,20 +163,20 @@ static int rkcanfd_rxstx_filter(struct rkcanfd_priv *priv,
 	 */
 	if ((cfd_nominal->can_id & (CAN_RTR_FLAG | CAN_SFF_MASK)) !=
 	    (cfd_rx->can_id & (CAN_RTR_FLAG | CAN_SFF_MASK)))
-		return 0;
+		goto out_unlock;
 
 	/* Not affected if:
 	 * - length is not the same
 	 */
 	if (cfd_nominal->len != cfd_rx->len)
-		return 0;
+		goto out_unlock;
 
 	/* Not affected if:
 	 * - the data of non RTR frames is different
 	 */
 	if (!(cfd_nominal->can_id & CAN_RTR_FLAG) &&
 	    memcmp(cfd_nominal->data, cfd_rx->data, cfd_nominal->len))
-		return 0;
+		goto out_unlock;
 
 	/* Affected by Erratum 6 */
 	u64_stats_update_begin(&rkcanfd_stats->syncp);

@@ -185,6 +197,9 @@ static int rkcanfd_rxstx_filter(struct rkcanfd_priv *priv,
 
 	rkcanfd_xmit_retry(priv);
 
+out_unlock:
+	spin_unlock_irqrestore(&priv->tx_lock, flags);
+
 	return 0;
 }
 

@@ -14,6 +14,8 @@ static bool rkcanfd_tx_tail_is_eff(const struct rkcanfd_priv *priv)
 	const struct sk_buff *skb;
 	unsigned int tx_tail;
 
+	lockdep_assert_held(&priv->tx_lock);
+
 	if (!rkcanfd_get_tx_pending(priv))
 		return false;
 

@@ -33,13 +35,22 @@ static bool rkcanfd_tx_tail_is_eff(const struct rkcanfd_priv *priv)
 	return cfd->can_id & CAN_EFF_FLAG;
 }
 
-unsigned int rkcanfd_get_effective_tx_free(const struct rkcanfd_priv *priv)
+unsigned int rkcanfd_get_effective_tx_free(struct rkcanfd_priv *priv)
 {
+	unsigned int tx_free;
+	unsigned long flags;
+
+	spin_lock_irqsave(&priv->tx_lock, flags);
+
 	if (priv->devtype_data.quirks & RKCANFD_QUIRK_RK3568_ERRATUM_6 &&
 	    rkcanfd_tx_tail_is_eff(priv))
-		return 0;
+		tx_free = 0;
+	else
+		tx_free = rkcanfd_get_tx_free(priv);
 
-	return rkcanfd_get_tx_free(priv);
+	spin_unlock_irqrestore(&priv->tx_lock, flags);
+
+	return tx_free;
 }
 
 static void rkcanfd_start_xmit_write_cmd(const struct rkcanfd_priv *priv,

@@ -60,6 +71,8 @@ void rkcanfd_xmit_retry(struct rkcanfd_priv *priv)
 	const unsigned int tx_tail = rkcanfd_get_tx_tail(priv);
 	const u32 reg_cmd = RKCANFD_REG_CMD_TX_REQ(tx_tail);
 
+	lockdep_assert_held(&priv->tx_lock);
+
 	rkcanfd_start_xmit_write_cmd(priv, reg_cmd);
 }
 

@@ -69,6 +82,7 @@ netdev_tx_t rkcanfd_start_xmit(struct sk_buff *skb, struct net_device *ndev)
 	u32 reg_frameinfo, reg_id, reg_cmd;
 	unsigned int tx_head, frame_len;
 	const struct canfd_frame *cfd;
+	unsigned long flags;
 	int err;
 	u8 i;
 

@@ -88,10 +102,13 @@ netdev_tx_t rkcanfd_start_xmit(struct sk_buff *skb, struct net_device *ndev)
 		return NETDEV_TX_BUSY;
 	}
 
+	spin_lock_irqsave(&priv->tx_lock, flags);
 	tx_head = rkcanfd_get_tx_head(priv);
 	frame_len = can_skb_get_frame_len(skb);
 	err = can_put_echo_skb(skb, ndev, tx_head, frame_len);
 	if (err) {
+		spin_unlock_irqrestore(&priv->tx_lock, flags);
+
 		ndev->stats.tx_dropped++;
 		return NETDEV_TX_OK;
 	}

@@ -136,6 +153,7 @@ netdev_tx_t rkcanfd_start_xmit(struct sk_buff *skb, struct net_device *ndev)
 	WRITE_ONCE(priv->tx_head, priv->tx_head + 1);
 
 	rkcanfd_start_xmit_write_cmd(priv, reg_cmd);
+	spin_unlock_irqrestore(&priv->tx_lock, flags);
 
 	netif_subqueue_maybe_stop(priv->ndev, 0,
 				  rkcanfd_get_effective_tx_free(priv),

@@ -152,6 +170,8 @@ void rkcanfd_handle_tx_done_one(struct rkcanfd_priv *priv, const u32 ts,
 	unsigned int tx_tail;
 	struct sk_buff *skb;
 
+	lockdep_assert_held(&priv->tx_lock);
+
 	tx_tail = rkcanfd_get_tx_tail(priv);
 	skb = priv->can.echo_skb[tx_tail];
 

@@ -15,6 +15,7 @@
 #include <linux/netdevice.h>
 #include <linux/reset.h>
 #include <linux/skbuff.h>
+#include <linux/spinlock.h>
 #include <linux/timecounter.h>
 #include <linux/types.h>
 #include <linux/u64_stats_sync.h>

@@ -474,6 +475,7 @@ struct rkcanfd_priv {
 	struct can_rx_offload offload;
 	struct net_device *ndev;
 
+	spinlock_t tx_lock; /* protects tx_head, tx_tail and echo_skb */
 	void __iomem *regs;
 	unsigned int tx_head;
 	unsigned int tx_tail;

@@ -556,7 +558,7 @@ void rkcanfd_timestamp_start(struct rkcanfd_priv *priv);
 void rkcanfd_timestamp_stop(struct rkcanfd_priv *priv);
 void rkcanfd_timestamp_stop_sync(struct rkcanfd_priv *priv);
 
-unsigned int rkcanfd_get_effective_tx_free(const struct rkcanfd_priv *priv);
+unsigned int rkcanfd_get_effective_tx_free(struct rkcanfd_priv *priv);
 void rkcanfd_xmit_retry(struct rkcanfd_priv *priv);
 netdev_tx_t rkcanfd_start_xmit(struct sk_buff *skb, struct net_device *ndev);
 void rkcanfd_handle_tx_done_one(struct rkcanfd_priv *priv, const u32 ts,