Merge branch 'mvpp2-fixes'

This change “Merge branch ‘mvpp2-fixes'” in Linux kernel is authored by David S. Miller <davem [at] davemloft.net> on Mon Aug 10 10:57:01 2015 -0700.

Merge branch 'mvpp2-fixes'

Marcin Wojtas says:

====================
Fixes for the network driver of Marvell Armada 375 SoC

This is a set of three patches that fix long-lasting problems implemented in
the initial support for the Armada 375 network controller.

Due to an inappropriate concept of handling the per-CPU sent packets'
processing on TX path the driver numerous problems occured, such as RCU
stalls. Those have been fixed, of which details you can find in the commit
logs. The patches were intensively tested on top of v4.2-rc5.

I'm looking forward to any comments or remarks.
====================

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

This Linux change may have been applied to various maintained Linux releases and you can find Linux releases including commit ea70858.

There is no are 0 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 drivers/net/ethernet/marvell/mvpp2.c | 177 +++++++++++++++++++++++++----------
 1 file changed, 130 insertions(+), 47 deletions(-)

diff --git a/drivers/net/ethernet/marvell/mvpp2.c b/drivers/net/ethernet/marvell/mvpp2.c
index 3e25d314..d9884fd 100644
--- a/drivers/net/ethernet/marvell/mvpp2.c
+++ b/drivers/net/ethernet/marvell/mvpp2.c
@@ -27,6 +27,8 @@
 #include <linux/of_address.h>
 #include <linux/phy.h>
 #include <linux/clk.h>
+#include <linux/hrtimer.h>
+#include <linux/ktime.h>
 #include <uapi/linux/ppp_defs.h>
 #include <net/ip.h>
 #include <net/ipv6.h>
@@ -299,6 +301,7 @@
 
 /* Coalescing */
 #define MVPP2_TXDONE_COAL_PKTS_THRESH	15
+#define MVPP2_TXDONE_HRTIMER_PERIOD_NS	1000000UL
 #define MVPP2_RX_COAL_PKTS		32
 #define MVPP2_RX_COAL_USEC		100
 
@@ -660,6 +663,14 @@ struct mvpp2_pcpu_stats {
 	u64	tx_bytes;
 };
 
+/* Per-CPU port control */
+struct mvpp2_port_pcpu {
+	struct hrtimer tx_done_timer;
+	bool timer_scheduled;
+	/* Tasklet for egress finalization */
+	struct tasklet_struct tx_done_tasklet;
+};
+
 struct mvpp2_port {
 	u8 id;
 
@@ -679,6 +690,9 @@ struct mvpp2_port {
 	u32 pending_cause_rx;
 	struct napi_struct napi;
 
+	/* Per-CPU port control */
+	struct mvpp2_port_pcpu __percpu *pcpu;
+
 	/* Flags */
 	unsigned long flags;
 
@@ -3798,7 +3812,6 @@ static void mvpp2_interrupts_unmask(void *arg)
 
 	mvpp2_write(port->priv, MVPP2_ISR_RX_TX_MASK_REG(port->id),
 		    (MVPP2_CAUSE_MISC_SUM_MASK |
-		     MVPP2_CAUSE_TXQ_OCCUP_DESC_ALL_MASK |
 		     MVPP2_CAUSE_RXQ_OCCUP_DESC_ALL_MASK));
 }
 
@@ -4374,23 +4387,6 @@ static void mvpp2_rx_time_coal_set(struct mvpp2_port *port,
 	rxq->time_coal = usec;
 }
 
-/* Set threshold for TX_DONE pkts coalescing */
-static void mvpp2_tx_done_pkts_coal_set(void *arg)
-{
-	struct mvpp2_port *port = arg;
-	int queue;
-	u32 val;
-
-	for (queue = 0; queue < txq_number; queue++) {
-		struct mvpp2_tx_queue *txq = port->txqs[queue];
-
-		val = (txq->done_pkts_coal << MVPP2_TRANSMITTED_THRESH_OFFSET) &
-		       MVPP2_TRANSMITTED_THRESH_MASK;
-		mvpp2_write(port->priv, MVPP2_TXQ_NUM_REG, txq->id);
-		mvpp2_write(port->priv, MVPP2_TXQ_THRESH_REG, val);
-	}
-}
-
 /* Free Tx queue skbuffs */
 static void mvpp2_txq_bufs_free(struct mvpp2_port *port,
 				struct mvpp2_tx_queue *txq,
@@ -4425,7 +4421,7 @@ static inline struct mvpp2_rx_queue *mvpp2_get_rx_queue(struct mvpp2_port *port,
 static inline struct mvpp2_tx_queue *mvpp2_get_tx_queue(struct mvpp2_port *port,
 							u32 cause)
 {
-	int queue = fls(cause >> 16) - 1;
+	int queue = fls(cause) - 1;
 
 	return port->txqs[queue];
 }
@@ -4452,6 +4448,29 @@ static void mvpp2_txq_done(struct mvpp2_port *port, struct mvpp2_tx_queue *txq,
 			netif_tx_wake_queue(nq);
 }
 
+static unsigned int mvpp2_tx_done(struct mvpp2_port *port, u32 cause)
+{
+	struct mvpp2_tx_queue *txq;
+	struct mvpp2_txq_pcpu *txq_pcpu;
+	unsigned int tx_todo = 0;
+
+	while (cause) {
+		txq = mvpp2_get_tx_queue(port, cause);
+		if (!txq)
+			break;
+
+		txq_pcpu = this_cpu_ptr(txq->pcpu);
+
+		if (txq_pcpu->count) {
+			mvpp2_txq_done(port, txq, txq_pcpu);
+			tx_todo += txq_pcpu->count;
+		}
+
+		cause &= ~(1 << txq->log_id);
+	}
+	return tx_todo;
+}
+
 /* Rx/Tx queue initialization/cleanup methods */
 
 /* Allocate and initialize descriptors for aggr TXQ */
@@ -4812,7 +4831,6 @@ static int mvpp2_setup_txqs(struct mvpp2_port *port)
 			goto err_cleanup;
 	}
 
-	on_each_cpu(mvpp2_tx_done_pkts_coal_set, port, 1);
 	on_each_cpu(mvpp2_txq_sent_counter_clear, port, 1);
 	return 0;
 
@@ -4894,6 +4912,49 @@ static void mvpp2_link_event(struct net_device *dev)
 	}
 }
 
+static void mvpp2_timer_set(struct mvpp2_port_pcpu *port_pcpu)
+{
+	ktime_t interval;
+
+	if (!port_pcpu->timer_scheduled) {
+		port_pcpu->timer_scheduled = true;
+		interval = ktime_set(0, MVPP2_TXDONE_HRTIMER_PERIOD_NS);
+		hrtimer_start(&port_pcpu->tx_done_timer, interval,
+			      HRTIMER_MODE_REL_PINNED);
+	}
+}
+
+static void mvpp2_tx_proc_cb(unsigned long data)
+{
+	struct net_device *dev = (struct net_device *)data;
+	struct mvpp2_port *port = netdev_priv(dev);
+	struct mvpp2_port_pcpu *port_pcpu = this_cpu_ptr(port->pcpu);
+	unsigned int tx_todo, cause;
+
+	if (!netif_running(dev))
+		return;
+	port_pcpu->timer_scheduled = false;
+
+	/* Process all the Tx queues */
+	cause = (1 << txq_number) - 1;
+	tx_todo = mvpp2_tx_done(port, cause);
+
+	/* Set the timer in case not all the packets were processed */
+	if (tx_todo)
+		mvpp2_timer_set(port_pcpu);
+}
+
+static enum hrtimer_restart mvpp2_hr_timer_cb(struct hrtimer *timer)
+{
+	struct mvpp2_port_pcpu *port_pcpu = container_of(timer,
+							 struct mvpp2_port_pcpu,
+							 tx_done_timer);
+
+	tasklet_schedule(&port_pcpu->tx_done_tasklet);
+
+	return HRTIMER_NORESTART;
+}
+
 /* Main RX/TX processing routines */
 
 /* Display more error info */
@@ -5262,6 +5323,17 @@ static int mvpp2_tx(struct sk_buff *skb, struct net_device *dev)
 		dev_kfree_skb_any(skb);
 	}
 
+	/* Finalize TX processing */
+	if (txq_pcpu->count >= txq->done_pkts_coal)
+		mvpp2_txq_done(port, txq, txq_pcpu);
+
+	/* Set the timer in case not all frags were processed */
+	if (txq_pcpu->count <= frags && txq_pcpu->count > 0) {
+		struct mvpp2_port_pcpu *port_pcpu = this_cpu_ptr(port->pcpu);
+
+		mvpp2_timer_set(port_pcpu);
+	}
+
 	return NETDEV_TX_OK;
 }
 
@@ -5275,10 +5347,11 @@ static inline void mvpp2_cause_error(struct net_device *dev, int cause)
 		netdev_err(dev, "tx fifo underrun errorn");
 }
 
-static void mvpp2_txq_done_percpu(void *arg)
+static int mvpp2_poll(struct napi_struct *napi, int budget)
 {
-	struct mvpp2_port *port = arg;
-	u32 cause_rx_tx, cause_tx, cause_misc;
+	u32 cause_rx_tx, cause_rx, cause_misc;
+	int rx_done = 0;
+	struct mvpp2_port *port = netdev_priv(napi->dev);
 
 	/* Rx/Tx cause register
 	 *
@@ -5292,7 +5365,7 @@ static void mvpp2_txq_done_percpu(void *arg)
 	 */
 	cause_rx_tx = mvpp2_read(port->priv,
 				 MVPP2_ISR_RX_TX_CAUSE_REG(port->id));
-	cause_tx = cause_rx_tx & MVPP2_CAUSE_TXQ_OCCUP_DESC_ALL_MASK;
+	cause_rx_tx &= ~MVPP2_CAUSE_TXQ_OCCUP_DESC_ALL_MASK;
 	cause_misc = cause_rx_tx & MVPP2_CAUSE_MISC_SUM_MASK;
 
 	if (cause_misc) {
@@ -5304,26 +5377,6 @@ static void mvpp2_txq_done_percpu(void *arg)
 			    cause_rx_tx & ~MVPP2_CAUSE_MISC_SUM_MASK);
 	}
 
-	/* Release TX descriptors */
-	if (cause_tx) {
-		struct mvpp2_tx_queue *txq = mvpp2_get_tx_queue(port, cause_tx);
-		struct mvpp2_txq_pcpu *txq_pcpu = this_cpu_ptr(txq->pcpu);
-
-		if (txq_pcpu->count)
-			mvpp2_txq_done(port, txq, txq_pcpu);
-	}
-}
-
-static int mvpp2_poll(struct napi_struct *napi, int budget)
-{
-	u32 cause_rx_tx, cause_rx;
-	int rx_done = 0;
-	struct mvpp2_port *port = netdev_priv(napi->dev);
-
-	on_each_cpu(mvpp2_txq_done_percpu, port, 1);
-
-	cause_rx_tx = mvpp2_read(port->priv,
-				 MVPP2_ISR_RX_TX_CAUSE_REG(port->id));
 	cause_rx = cause_rx_tx & MVPP2_CAUSE_RXQ_OCCUP_DESC_ALL_MASK;
 
 	/* Process RX packets */
@@ -5568,6 +5621,8 @@ static int mvpp2_open(struct net_device *dev)
 static int mvpp2_stop(struct net_device *dev)
 {
 	struct mvpp2_port *port = netdev_priv(dev);
+	struct mvpp2_port_pcpu *port_pcpu;
+	int cpu;
 
 	mvpp2_stop_dev(port);
 	mvpp2_phy_disconnect(port);
@@ -5576,6 +5631,13 @@ static int mvpp2_stop(struct net_device *dev)
 	on_each_cpu(mvpp2_interrupts_mask, port, 1);
 
 	free_irq(port->irq, port);
+	for_each_present_cpu(cpu) {
+		port_pcpu = per_cpu_ptr(port->pcpu, cpu);
+
+		hrtimer_cancel(&port_pcpu->tx_done_timer);
+		port_pcpu->timer_scheduled = false;
+		tasklet_kill(&port_pcpu->tx_done_tasklet);
+	}
 	mvpp2_cleanup_rxqs(port);
 	mvpp2_cleanup_txqs(port);
 
@@ -5791,7 +5853,6 @@ static int mvpp2_ethtool_set_coalesce(struct net_device *dev,
 		txq->done_pkts_coal = c->tx_max_coalesced_frames;
 	}
 
-	on_each_cpu(mvpp2_tx_done_pkts_coal_set, port, 1);
 	return 0;
 }
 
@@ -6042,6 +6103,7 @@ static int mvpp2_port_probe(struct platform_device *pdev,
 {
 	struct device_node *phy_node;
 	struct mvpp2_port *port;
+	struct mvpp2_port_pcpu *port_pcpu;
 	struct net_device *dev;
 	struct resource *res;
 	const char *dt_mac_addr;
@@ -6051,7 +6113,7 @@ static int mvpp2_port_probe(struct platform_device *pdev,
 	int features;
 	int phy_mode;
 	int priv_common_regs_num = 2;
-	int err, i;
+	int err, i, cpu;
 
 	dev = alloc_etherdev_mqs(sizeof(struct mvpp2_port), txq_number,
 				 rxq_number);
@@ -6142,6 +6204,24 @@ static int mvpp2_port_probe(struct platform_device *pdev,
 	}
 	mvpp2_port_power_up(port);
 
+	port->pcpu = alloc_percpu(struct mvpp2_port_pcpu);
+	if (!port->pcpu) {
+		err = -ENOMEM;
+		goto err_free_txq_pcpu;
+	}
+
+	for_each_present_cpu(cpu) {
+		port_pcpu = per_cpu_ptr(port->pcpu, cpu);
+
+		hrtimer_init(&port_pcpu->tx_done_timer, CLOCK_MONOTONIC,
+			     HRTIMER_MODE_REL_PINNED);
+		port_pcpu->tx_done_timer.function = mvpp2_hr_timer_cb;
+		port_pcpu->timer_scheduled = false;
+
+		tasklet_init(&port_pcpu->tx_done_tasklet, mvpp2_tx_proc_cb,
+			     (unsigned long)dev);
+	}
+
 	netif_napi_add(dev, &port->napi, mvpp2_poll, NAPI_POLL_WEIGHT);
 	features = NETIF_F_SG | NETIF_F_IP_CSUM;
 	dev->features = features | NETIF_F_RXCSUM;
@@ -6151,7 +6231,7 @@ static int mvpp2_port_probe(struct platform_device *pdev,
 	err = register_netdev(dev);
 	if (err < 0) {
 		dev_err(&pdev->dev, "failed to register netdevn");
-		goto err_free_txq_pcpu;
+		goto err_free_port_pcpu;
 	}
 	netdev_info(dev, "Using %s mac address %pMn", mac_from, dev->dev_addr);
 
@@ -6160,6 +6240,8 @@ static int mvpp2_port_probe(struct platform_device *pdev,
 	priv->port_list[id] = port;
 	return 0;
 
+err_free_port_pcpu:
+	free_percpu(port->pcpu);
 err_free_txq_pcpu:
 	for (i = 0; i < txq_number; i++)
 		free_percpu(port->txqs[i]->pcpu);
@@ -6178,6 +6260,7 @@ static void mvpp2_port_remove(struct mvpp2_port *port)
 	int i;
 
 	unregister_netdev(port->dev);
+	free_percpu(port->pcpu);
 	free_percpu(port->stats);
 	for (i = 0; i < txq_number; i++)
 		free_percpu(port->txqs[i]->pcpu);

The commit for this change in Linux stable tree is ea70858 (patch).

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