netdev - [net-next 14/15] ixgbe: Replace rmb in Tx cleanup with read_barrier

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Message-Id: <1360058548-18158-15-git-send-email-jeffrey.t.kirsher@intel.com>
Date:	Tue,  5 Feb 2013 02:02:27 -0800
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,
	Jeff Kirsher <jeffrey.t.kirsher@...el.com>
Subject: [net-next 14/15] ixgbe: Replace rmb in Tx cleanup with read_barrier_depends

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

The rmb in the Tx cleanup path is a much stronger barrier than we really need.
All that is really needed is a read_barrier_depends since the location of the
EOP descriptor is dependent on the eop_desc value.

Signed-off-by: Alexander Duyck <alexander.h.duyck@...el.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@...el.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@...el.com>
---
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index 88500dd..ef9cb0a 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -838,7 +838,7 @@ static bool ixgbe_clean_tx_irq(struct ixgbe_q_vector *q_vector,
 			break;
 
 		/* prevent any other reads prior to eop_desc */
-		rmb();
+		read_barrier_depends();
 
 		/* if DD is not set pending work has not been completed */
 		if (!(eop_desc->wb.status & cpu_to_le32(IXGBE_TXD_STAT_DD)))
-- 
1.7.11.7

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