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: Vlastimil Setka <setka@vsis.cz>
Signed-off-by: Roman Pisl <rpisl@kky.zcu.cz>
Signed-off-by: Vince Bridgers <vbridger@opensource.altera.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/altera/altera_tse_main.c b/drivers/net/ethernet/altera/altera_tse_main.c
index f3d784a3463dc02f1dd30c1512eb8a2cce1d7516..6725dc00750bd6da367396bceb33adaac10842d0 100644 (file)
--- a/drivers/net/ethernet/altera/altera_tse_main.c
+++ b/drivers/net/ethernet/altera/altera_tse_main.c
@@ -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);
+               napi_gro_flush(napi, false);
+               __napi_complete(napi);
 
-       netdev_dbg(priv->dev,
-                  "NAPI Complete, did %d packets with budget %d\n",
-                  txcomplete+rxcomplete, budget);
+               netdev_dbg(priv->dev,
+                          "NAPI Complete, did %d packets with budget %d\n",
+                          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;
+               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;
 }
 
 /* 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;
 }