r8169: fix memory corruption on retrieval of hardware statistics.

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>

diff --git a/drivers/net/ethernet/realtek/r8169.c b/drivers/net/ethernet/realtek/r8169.c
index fc0d5fa65ad4c1ca02073e2d1d1554df68443e86..734286ebe5ef557c0d2738702e86081552c68cc5 100644 (file)
--- a/drivers/net/ethernet/realtek/r8169.c
+++ b/drivers/net/ethernet/realtek/r8169.c
@@ -2244,19 +2244,14 @@ static bool rtl8169_do_counters(struct net_device *dev, u32 counter_cmd)
        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)