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Commit 8d4ac39d authored by Vlastimil Setka's avatar Vlastimil Setka Committed by David S. Miller
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altera_tse: Fixes in NAPI and interrupt handling paths 



Incorrect NAPI polling caused WARNING at net/core/dev.c net_rx_action.
Some stability issues were also seen at high throughput and system
load before this patch.

This patch contains several changes in altera_tse_main.c:

- tse_rx() is fixed to not process more than `limit` frames

- tse_poll() is refactored to match NAPI logic
  - only received frames are counted for return value
  - removed bogus condition `(rxcomplete >= budget || txcomplete > 0)`
  - replace by: if (rxcomplete < budget) -> call __napi_complete and enable irq

- altera_isr()
  - replace spin_lock_irqsave() by spin_lock() - we are in isr
  - use spinlocks just over irq manipulation, not over __napi_schedule
  - reset IRQ first, then disable and schedule napi

This is a cleaned up resubmission from Vlastimil's recent submission.

Signed-off-by: default avatarVlastimil Setka <setka@vsis.cz>
Signed-off-by: default avatarRoman Pisl <rpisl@kky.zcu.cz>
Signed-off-by: default avatarVince Bridgers <vbridger@opensource.altera.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent fe6e4081

drivers/net/ethernet/altera/altera_tse_main.c

+22 −23
Original line number Diff line number Diff line
@@ -376,7 +376,8 @@ static int tse_rx(struct altera_tse_private *priv, int limit) 
	u16 pktlength;

	u16 pktstatus;



	while ((rxstatus = priv->dmaops->get_rx_status(priv)) != 0) {

	while (((rxstatus = priv->dmaops->get_rx_status(priv)) != 0) &&

	       (count < limit))  {

		pktstatus = rxstatus >> 16;

		pktlength = rxstatus & 0xffff;
@@ -491,28 +492,27 @@ static int tse_poll(struct napi_struct *napi, int budget) 
	struct altera_tse_private *priv =

			container_of(napi, struct altera_tse_private, napi);

	int rxcomplete = 0;

	int txcomplete = 0;

	unsigned long int flags;



	txcomplete = tse_tx_complete(priv);

	tse_tx_complete(priv);



	rxcomplete = tse_rx(priv, budget);



	if (rxcomplete >= budget || txcomplete > 0)

		return rxcomplete;

	if (rxcomplete < budget) {



		napi_gro_flush(napi, false);

		__napi_complete(napi);



		netdev_dbg(priv->dev,

			   "NAPI Complete, did %d packets with budget %d\n",

		   txcomplete+rxcomplete, budget);

			   rxcomplete, budget);



		spin_lock_irqsave(&priv->rxdma_irq_lock, flags);

		priv->dmaops->enable_rxirq(priv);

		priv->dmaops->enable_txirq(priv);

		spin_unlock_irqrestore(&priv->rxdma_irq_lock, flags);

	return rxcomplete + txcomplete;

	}

	return rxcomplete;

}



/* DMA TX & RX FIFO interrupt routing
@@ -521,7 +521,6 @@ static irqreturn_t altera_isr(int irq, void *dev_id) 
{

	struct net_device *dev = dev_id;

	struct altera_tse_private *priv;

	unsigned long int flags;



	if (unlikely(!dev)) {

		pr_err("%s: invalid dev pointer\n", __func__);
@@ -529,20 +528,20 @@ static irqreturn_t altera_isr(int irq, void *dev_id) 
	}

	priv = netdev_priv(dev);



	/* turn off desc irqs and enable napi rx */

	spin_lock_irqsave(&priv->rxdma_irq_lock, flags);

	spin_lock(&priv->rxdma_irq_lock);

	/* reset IRQs */

	priv->dmaops->clear_rxirq(priv);

	priv->dmaops->clear_txirq(priv);

	spin_unlock(&priv->rxdma_irq_lock);



	if (likely(napi_schedule_prep(&priv->napi))) {

		spin_lock(&priv->rxdma_irq_lock);

		priv->dmaops->disable_rxirq(priv);

		priv->dmaops->disable_txirq(priv);

		spin_unlock(&priv->rxdma_irq_lock);

		__napi_schedule(&priv->napi);

	}



	/* reset IRQs */

	priv->dmaops->clear_rxirq(priv);

	priv->dmaops->clear_txirq(priv);



	spin_unlock_irqrestore(&priv->rxdma_irq_lock, flags);



	return IRQ_HANDLED;

}