netdev - [net-next 2/9] ixgbevf: Do not rewind the Rx ring before bumping tail

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Date:	Wed, 18 Jul 2012 13:31:49 -0700
From:	Jeff Kirsher <jeffrey.t.kirsher@...el.com>
To:	davem@...emloft.net
Cc:	Alexander Duyck <alexander.h.duyck@...el.com>,
	netdev@...r.kernel.org, gospo@...hat.com, sassmann@...hat.com,
	Greg Rose <gregory.v.rose@...el.com>,
	Jeff Kirsher <jeffrey.t.kirsher@...el.com>
Subject: [net-next 2/9] ixgbevf: Do not rewind the Rx ring before bumping tail

From: Alexander Duyck <alexander.h.duyck@...el.com>

The driver is going back one step from its' previous location before
bumping tail. This is incorrect.  We should just be writing the value of
next_to_use into the tail register.

Signed-off-by: Alexander Duyck <alexander.h.duyck@...el.com>
Signed-off-by: Greg Rose <gregory.v.rose@...el.com>
Tested-by: Sibai Li <sibai.li@...el.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@...el.com>
---
 drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c |    7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
index b88218c..c27ce44 100644
--- a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
+++ b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
@@ -375,8 +375,6 @@ static void ixgbevf_alloc_rx_buffers(struct ixgbevf_adapter *adapter,
 no_buffers:
 	if (rx_ring->next_to_use != i) {
 		rx_ring->next_to_use = i;
-		if (i-- == 0)
-			i = (rx_ring->count - 1);
 
 		ixgbevf_release_rx_desc(&adapter->hw, rx_ring, i);
 	}
@@ -1240,9 +1238,8 @@ static void ixgbevf_configure(struct ixgbevf_adapter *adapter)
 	ixgbevf_configure_rx(adapter);
 	for (i = 0; i < adapter->num_rx_queues; i++) {
 		struct ixgbevf_ring *ring = &adapter->rx_ring[i];
-		ixgbevf_alloc_rx_buffers(adapter, ring, ring->count);
-		ring->next_to_use = ring->count - 1;
-		writel(ring->next_to_use, adapter->hw.hw_addr + ring->tail);
+		ixgbevf_alloc_rx_buffers(adapter, ring,
+					 IXGBE_DESC_UNUSED(ring));
 	}
 }
 
-- 
1.7.10.4

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