[PATCH 4.4 67/74] r8169: fix memory corruption on retrieval of hardware statistics.

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Francois Romieu <romieu@fr.zoreil.com>


[ Upstream commit a78e93661c5fd30b9e1dee464b2f62f966883ef7 ]

Hardware statistics retrieval hurts in tight invocation loops.

Avoid extraneous write and enforce strict ordering of writes targeted to
the tally counters dump area address registers.

Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>
Tested-by: Oliver Freyermuth <o.freyermuth@googlemail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/ethernet/realtek/r8169.c |    9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

--- a/drivers/net/ethernet/realtek/r8169.c
+++ b/drivers/net/ethernet/realtek/r8169.c
@@ -2205,19 +2205,14 @@ static bool rtl8169_do_counters(struct n
 	void __iomem *ioaddr = tp->mmio_addr;
 	dma_addr_t paddr = tp->counters_phys_addr;
 	u32 cmd;
-	bool ret;
 
 	RTL_W32(CounterAddrHigh, (u64)paddr >> 32);
+	RTL_R32(CounterAddrHigh);
 	cmd = (u64)paddr & DMA_BIT_MASK(32);
 	RTL_W32(CounterAddrLow, cmd);
 	RTL_W32(CounterAddrLow, cmd | counter_cmd);
 
-	ret = rtl_udelay_loop_wait_low(tp, &rtl_counters_cond, 10, 1000);
-
-	RTL_W32(CounterAddrLow, 0);
-	RTL_W32(CounterAddrHigh, 0);
-
-	return ret;
+	return rtl_udelay_loop_wait_low(tp, &rtl_counters_cond, 10, 1000);
 }
 
 static bool rtl8169_reset_counters(struct net_device *dev)