RE: [PATCH] e1000: Reset rx ring index on receive overrun

[Dave, Tushar N]

I am interested in to see if you have actual test case and more importantly test data that shows that kernel and device indexes are not synchronized any more.


-Tushar

>-----Original Message-----
>From: netdev-owner@xxxxxxxxxxxxxxx [mailto:netdev-owner@xxxxxxxxxxxxxxx]
>On Behalf Of Samuel Thibault
>Sent: Thursday, May 17, 2012 4:02 PM
>To: Kirsher, Jeffrey T; Brandeburg, Jesse; Allan, Bruce W; Wyborny,
>Carolyn; Skidmore, Donald C; Rose, Gregory V; Waskiewicz Jr, Peter P;
>Duyck, Alexander H; Ronciak, John; David S. Miller; Jiri Pirko; Dean
>Nelson; e1000-devel@xxxxxxxxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx
>Cc: linux-kernel@xxxxxxxxxxxxxxx
>Subject: [PATCH] e1000: Reset rx ring index on receive overrun
>
>At high traffic rate, the rx ring may get completely filled before we
>manage to consume it.  After it is filled, the kernel and device indexes
>are not synchronized any more, so we have to reset them, otherwise the
>kernel will be stuck waiting for the wrong slot to be filled.
>
>Signed-off-by: Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>
>
>---
>This is just a patch suggestion, I'm not an expert in network drivers, I
>leave to actual driver authors to bake a better version.
>
>diff --git a/drivers/net/ethernet/intel/e1000/e1000_main.c
>b/drivers/net/ethernet/intel/e1000/e1000_main.c
>index 37caa88..77c8dbc 100644
>--- a/drivers/net/ethernet/intel/e1000/e1000_main.c
>+++ b/drivers/net/ethernet/intel/e1000/e1000_main.c
>@@ -3759,6 +3759,21 @@ static irqreturn_t e1000_intr(int irq, void *data)
> 	if (unlikely(test_bit(__E1000_DOWN, &adapter->flags)))
> 		return IRQ_HANDLED;
>
>+	if (unlikely(icr & E1000_ICR_RXO)) {
>+		/* Receive Overrun */
>+		u32 rctl;
>+		int i;
>+		rctl = er32(RCTL);
>+		ew32(RCTL, rctl & ~E1000_RCTL_EN);
>+		for (i = 0; i < adapter->num_rx_queues; i++) {
>+			memset(adapter->rx_ring[i].desc, 0, adapter-
>>rx_ring[i].size);
>+			adapter->rx_ring[i].next_to_clean = 0;
>+		}
>+		ew32(RDH, 0);
>+		ew32(RCTL, rctl);
>+		adapter->netdev->stats.rx_fifo_errors++;
>+	}
>+
> 	if (unlikely(icr & (E1000_ICR_RXSEQ | E1000_ICR_LSC))) {
> 		hw->get_link_status = 1;
> 		/* guard against interrupt when we're going down */
>--
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