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net: macb: manage Rx BNA error to avoid race condition #44

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net: macb: manage Rx BNA error to avoid race condition #44

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763d331
net: macb: Incomplete received frame is not a critical error
yseraf Jun 11, 2020
3b542e6
net: macb: Manage BNA (Buffer Not Available) error and remove race co…
yseraf Jun 11, 2020
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75 changes: 73 additions & 2 deletions drivers/net/ethernet/cadence/macb_main.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1144,7 +1144,7 @@ static int gem_rx(struct macb_queue *queue, struct napi_struct *napi,
count++;

if (!(ctrl & MACB_BIT(RX_SOF) && ctrl & MACB_BIT(RX_EOF))) {
netdev_err(bp->dev,
netdev_warn(bp->dev,
"not whole frame pointed by descriptor\n");
bp->dev->stats.rx_dropped++;
queue->stats.rx_dropped++;
Expand Down Expand Up @@ -1378,6 +1378,73 @@ static int macb_rx(struct macb_queue *queue, struct napi_struct *napi,
return received;
}

static int gem_poll(struct napi_struct *napi, int budget)
{
struct macb_queue *queue = container_of(napi, struct macb_queue, napi);
struct macb *bp = queue->bp;
int work_done;
u32 status;

status = macb_readl(bp, RSR);
/* Don't clear yet the BNA error bit if any */
status &= ~MACB_BIT(BNA);
macb_writel(bp, RSR, status);


netdev_vdbg(bp->dev, "poll: status = %08lx, budget = %d\n",
(unsigned long)status, budget);

work_done = bp->macbgem_ops.mog_rx(queue, napi, budget);

if (work_done < budget) {
napi_complete_done(napi, work_done);

/* Packets received while interrupts were disabled or BNA error */
status = macb_readl(bp, RSR);
if (status) {
if (bp->caps & MACB_CAPS_ISR_CLEAR_ON_WRITE)
queue_writel(queue, ISR, MACB_BIT(RCOMP));

if (unlikely(status & MACB_BIT(BNA))) {
netdev_warn(bp->dev,
"buffer not available for incoming packet\n");

/* disable Rx interrupts and eventual HRESP error */
queue_writel(queue, IDR, bp->rx_intr_mask | MACB_BIT(HRESP));

/* free a slot to allow the refill */
queue->rx_tail++;
bp->dev->stats.rx_dropped++;
queue->stats.rx_dropped++;

/* clear the error before resolving it to avoid a race */
macb_writel(bp, RSR, MACB_BIT(BNA));

/* refill one slot to make it available for the DMA */
gem_rx_refill(queue);

/* enable Rx interrupts */
queue_writel(queue, IER, bp->rx_intr_mask | MACB_BIT(HRESP));
}

napi_reschedule(napi);
} else {
queue_writel(queue, IER, bp->rx_intr_mask);

/* IRQ are disabled, not masked. Reschedule to avoid a race */
status = macb_readl(bp, RSR);
if (status) {
queue_writel(queue, IER, bp->rx_intr_mask);
napi_reschedule(napi);
}
}
}

/* TODO: Handle errors */

return work_done;
}

static int macb_poll(struct napi_struct *napi, int budget)
{
struct macb_queue *queue = container_of(napi, struct macb_queue, napi);
Expand Down Expand Up @@ -3571,7 +3638,11 @@ static int macb_init(struct platform_device *pdev)

queue = &bp->queues[q];
queue->bp = bp;
netif_napi_add(dev, &queue->napi, macb_poll, NAPI_POLL_WEIGHT);
if (macb_is_gem(bp)) {
netif_napi_add(dev, &queue->napi, gem_poll, NAPI_POLL_WEIGHT);
} else {
netif_napi_add(dev, &queue->napi, macb_poll, NAPI_POLL_WEIGHT);
}
if (hw_q) {
queue->ISR = GEM_ISR(hw_q - 1);
queue->IER = GEM_IER(hw_q - 1);
Expand Down