davinci_mdio: Fix MDIO timeout check

Under heavy load (flood ping) it is possible for the MDIO timeout to
expire before the loop checks the GO bit again. This patch adds an
additional check whether the operation was done before actually
returning -ETIMEDOUT.

To reproduce this bug, flood ping the device, e.g., ping -f -l 1000
After some time, a "timed out waiting for user access" warning
may appear. And even worse, link may go down since the PHY reported a
timeout.

Signed-off-by: Christian Riesch <christian.riesch@omicron.at>
Cc: <stable@vger.kernel.org>
Cc: Cyril Chemparathy <cyril@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/ti/davinci_mdio.c b/drivers/net/ethernet/ti/davinci_mdio.c
index 2757c7d6e6330460c179d025a1ddc2267d32b27d..e4e47088e26b98fe0118c16ae17da61ec0f07dde 100644 (file)
--- a/drivers/net/ethernet/ti/davinci_mdio.c
+++ b/drivers/net/ethernet/ti/davinci_mdio.c
@@ -181,6 +181,11 @@ static inline int wait_for_user_access(struct davinci_mdio_data *data)
                __davinci_mdio_reset(data);
                return -EAGAIN;
        }
+
+       reg = __raw_readl(&regs->user[0].access);
+       if ((reg & USERACCESS_GO) == 0)
+               return 0;
+
        dev_err(data->dev, "timed out waiting for user access\n");
        return -ETIMEDOUT;
 }