Merge branch 'SJA1105-DSA-locking-fixes-for-PTP'

Vladimir Oltean says:

====================
SJA1105 DSA locking fixes for PTP

This series fixes the locking API usage problems spotted when compiling
the kernel with CONFIG_DEBUG_ATOMIC_SLEEP=y and CONFIG_DEBUG_SPINLOCK=y.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 26 insertions, 10 deletions

diff --git a/drivers/net/dsa/sja1105/sja1105_main.c b/drivers/net/dsa/sja1105/sja1105_main.c
index f3d38ff144c4..7687ddcae159 100644
--- a/drivers/net/dsa/sja1105/sja1105_main.c
+++ b/drivers/net/dsa/sja1105/sja1105_main.c
@@ -1897,7 +1897,9 @@ static int sja1105_set_ageing_time(struct dsa_switch *ds,
 	return sja1105_static_config_reload(priv);
 }
 
-/* Caller must hold priv->tagger_data.meta_lock */
+/* Must be called only with priv->tagger_data.state bit
+ * SJA1105_HWTS_RX_EN cleared
+ */
 static int sja1105_change_rxtstamping(struct sja1105_private *priv,
 				      bool on)
 {
@@ -1954,16 +1956,17 @@ static int sja1105_hwtstamp_set(struct dsa_switch *ds, int port,
 		break;
 	}
 
-	if (rx_on != priv->tagger_data.hwts_rx_en) {
-		spin_lock(&priv->tagger_data.meta_lock);
+	if (rx_on != test_bit(SJA1105_HWTS_RX_EN, &priv->tagger_data.state)) {
+		clear_bit(SJA1105_HWTS_RX_EN, &priv->tagger_data.state);
+
 		rc = sja1105_change_rxtstamping(priv, rx_on);
-		spin_unlock(&priv->tagger_data.meta_lock);
 		if (rc < 0) {
 			dev_err(ds->dev,
 				"Failed to change RX timestamping: %d\n", rc);
-			return -EFAULT;
+			return rc;
 		}
-		priv->tagger_data.hwts_rx_en = rx_on;
+		if (rx_on)
+			set_bit(SJA1105_HWTS_RX_EN, &priv->tagger_data.state);
 	}
 
 	if (copy_to_user(ifr->ifr_data, &config, sizeof(config)))
@@ -1982,7 +1985,7 @@ static int sja1105_hwtstamp_get(struct dsa_switch *ds, int port,
 		config.tx_type = HWTSTAMP_TX_ON;
 	else
 		config.tx_type = HWTSTAMP_TX_OFF;
-	if (priv->tagger_data.hwts_rx_en)
+	if (test_bit(SJA1105_HWTS_RX_EN, &priv->tagger_data.state))
 		config.rx_filter = HWTSTAMP_FILTER_PTP_V2_L2_EVENT;
 	else
 		config.rx_filter = HWTSTAMP_FILTER_NONE;
@@ -2031,7 +2034,7 @@ static bool sja1105_port_rxtstamp(struct dsa_switch *ds, int port,
 	struct sja1105_private *priv = ds->priv;
 	struct sja1105_tagger_data *data = &priv->tagger_data;
 
-	if (!data->hwts_rx_en)
+	if (!test_bit(SJA1105_HWTS_RX_EN, &data->state))
 		return false;
 
 	/* We need to read the full PTP clock to reconstruct the Rx
@@ -2201,6 +2204,7 @@ static int sja1105_probe(struct spi_device *spi)
 	tagger_data = &priv->tagger_data;
 	skb_queue_head_init(&tagger_data->skb_rxtstamp_queue);
 	INIT_WORK(&tagger_data->rxtstamp_work, sja1105_rxtstamp_work);
+	spin_lock_init(&tagger_data->meta_lock);
 
 	/* Connections between dsa_port and sja1105_port */
 	for (i = 0; i < SJA1105_NUM_PORTS; i++) {
diff --git a/include/linux/dsa/sja1105.h b/include/linux/dsa/sja1105.h
index 79435cfc20eb..897e799dbcb9 100644
--- a/include/linux/dsa/sja1105.h
+++ b/include/linux/dsa/sja1105.h
@@ -31,6 +31,8 @@
 #define SJA1105_META_SMAC			0x222222222222ull
 #define SJA1105_META_DMAC			0x0180C200000Eull
 
+#define SJA1105_HWTS_RX_EN			0
+
 /* Global tagger data: each struct sja1105_port has a reference to
  * the structure defined in struct sja1105_private.
  */
@@ -42,7 +44,7 @@ struct sja1105_tagger_data {
 	 * from taggers running on multiple ports on SMP systems
 	 */
 	spinlock_t meta_lock;
-	bool hwts_rx_en;
+	unsigned long state;
 };
 
 struct sja1105_skb_cb {
diff --git a/net/dsa/tag_sja1105.c b/net/dsa/tag_sja1105.c
index 9c9aff3e52cf..63ef2a14c934 100644
--- a/net/dsa/tag_sja1105.c
+++ b/net/dsa/tag_sja1105.c
@@ -156,7 +156,11 @@ static struct sk_buff
 	/* Step 1: A timestampable frame was received.
 	 * Buffer it until we get its meta frame.
 	 */
-	if (is_link_local && sp->data->hwts_rx_en) {
+	if (is_link_local) {
+		if (!test_bit(SJA1105_HWTS_RX_EN, &sp->data->state))
+			/* Do normal processing. */
+			return skb;
+
 		spin_lock(&sp->data->meta_lock);
 		/* Was this a link-local frame instead of the meta
 		 * that we were expecting?
@@ -187,6 +191,12 @@ static struct sk_buff
 	} else if (is_meta) {
 		struct sk_buff *stampable_skb;
 
+		/* Drop the meta frame if we're not in the right state
+		 * to process it.
+		 */
+		if (!test_bit(SJA1105_HWTS_RX_EN, &sp->data->state))
+			return NULL;
+
 		spin_lock(&sp->data->meta_lock);
 
 		stampable_skb = sp->data->stampable_skb;