On 11/26/2016 04:20 AM, Lino Sanfilippo wrote:

Add driver for Alacritech gigabit ethernet cards with SLIC (session-layer
interface control) technology. The driver provides basic support without
SLIC for the following devices:

- Mojave cards (single port PCI Gigabit) both copper and fiber
- Oasis cards (single and dual port PCI-x Gigabit) copper and fiber
- Kalahari cards (dual and quad port PCI-e Gigabit) copper and fiber

This looks great, a few nits below:

+#define SLIC_MAX_TX_COMPLETIONS		100

You usually don't want to limit the number of TX completion, if the
entire TX ring needs to be cleaned, you would want to allow that.

[snip]

+	while (slic_get_free_rx_descs(rxq) > SLIC_MAX_REQ_RX_DESCS) {
+		skb = alloc_skb(maplen + ALIGN_MASK, gfp);
+		if (!skb)
+			break;
+
+		paddr = dma_map_single(&sdev->pdev->dev, skb->data, maplen,
+				       DMA_FROM_DEVICE);
+		if (dma_mapping_error(&sdev->pdev->dev, paddr)) {
+			netdev_err(dev, "mapping rx packet failed\n");
+			/* drop skb */
+			dev_kfree_skb_any(skb);
+			break;
+		}
+		/* ensure head buffer descriptors are 256 byte aligned */
+		offset = 0;
+		misalign = paddr & ALIGN_MASK;
+		if (misalign) {
+			offset = SLIC_RX_BUFF_ALIGN - misalign;
+			skb_reserve(skb, offset);
+		}
+		/* the HW expects dma chunks for descriptor + frame data */
+		desc = (struct slic_rx_desc *)skb->data;
+		memset(desc, 0, sizeof(*desc));

Do you really need to zero-out the prepending RX descriptor? Are not you
missing a write barrier here?

[snip]

+
+		dma_sync_single_for_cpu(&sdev->pdev->dev,
+					dma_unmap_addr(buff, map_addr),
+					buff->addr_offset + sizeof(*desc),
+					DMA_FROM_DEVICE);
+
+		status = le32_to_cpu(desc->status);
+		if (!(status & SLIC_IRHDDR_SVALID))
+			break;
+
+		buff->skb = NULL;
+
+		dma_unmap_single(&sdev->pdev->dev,
+				 dma_unmap_addr(buff, map_addr),
+				 dma_unmap_len(buff, map_len),
+				 DMA_FROM_DEVICE);

This is potentially inefficient, you already did a cache invalidation
for the RX descriptor here, you could be more efficient with just
invalidating the packet length, minus the descriptor length.

+
+		/* skip rx descriptor that is placed before the frame data */
+		skb_reserve(skb, SLIC_RX_BUFF_HDR_SIZE);
+
+		if (unlikely(status & SLIC_IRHDDR_ERR)) {
+			slic_handle_frame_error(sdev, skb);
+			dev_kfree_skb_any(skb);
+		} else {
+			struct ethhdr *eh = (struct ethhdr *)skb->data;
+
+			if (is_multicast_ether_addr(eh->h_dest))
+				SLIC_INC_STATS_COUNTER(&sdev->stats, rx_mcasts);
+
+			len = le32_to_cpu(desc->length) & SLIC_IRHDDR_FLEN_MSK;
+			skb_put(skb, len);
+			skb->protocol = eth_type_trans(skb, dev);
+			skb->ip_summed = CHECKSUM_UNNECESSARY;
+			skb->dev = dev;

eth_type_trans() already assigns skb->dev = dev;

+static int slic_poll(struct napi_struct *napi, int todo)
+{
+	struct slic_device *sdev = container_of(napi, struct slic_device, napi);
+	struct slic_shmem *sm = &sdev->shmem;
+	struct slic_shmem_data *sm_data = sm->shmem_data;
+	u32 isr = le32_to_cpu(sm_data->isr);
+	unsigned int done = 0;
+
+	slic_handle_irq(sdev, isr, todo, &done);
+
+	if (done < todo) {
+		napi_complete(napi);

napi_complete_done() since you know how many packets you completed.

+		/* reenable irqs */
+		sm_data->isr = 0;
+		/* make sure sm_data->isr is cleard before irqs are reenabled */
+		wmb();
+		slic_write(sdev, SLIC_REG_ISR, 0);
+		slic_flush_write(sdev);
+	}
+
+	return done;
+}
+
+static irqreturn_t slic_irq(int irq, void *dev_id)
+{
+	struct slic_device *sdev = dev_id;
+	struct slic_shmem *sm = &sdev->shmem;
+	struct slic_shmem_data *sm_data = sm->shmem_data;
+
+	slic_write(sdev, SLIC_REG_ICR, SLIC_ICR_INT_MASK);
+	slic_flush_write(sdev);
+	/* make sure sm_data->isr is read after ICR_INT_MASK is set */
+	wmb();
+
+	if (!sm_data->isr) {
+		dma_rmb();
+		/* spurious interrupt */
+		slic_write(sdev, SLIC_REG_ISR, 0);
+		slic_flush_write(sdev);
+		return IRQ_NONE;
+	}
+
+	napi_schedule(&sdev->napi);

Likewise napi_schedule_irqoff() can be used here.
-- 
Florian