usbnet: add a mutex around phy register access

When working on the mcs7830, I noticed the need for a mutex in its
mdio_read/mdio_write functions. A related problem seems to be present
in the asix driver in the respective functions.

This introduces a mutex in the common usbnet driver and uses it
from the two hardware specific drivers.

Acked-by: David Hollis <dhollis@davehollis.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

4 files changed, 11 insertions, 0 deletions

diff --git a/drivers/usb/net/asix.c b/drivers/usb/net/asix.c
index 5edd0534c7ab..881841e600de 100644
--- a/drivers/usb/net/asix.c
+++ b/drivers/usb/net/asix.c
@@ -569,10 +569,12 @@ static int asix_mdio_read(struct net_device *netdev, int phy_id, int loc)
         struct usbnet *dev = netdev_priv(netdev);
         u16 res;
 
+        mutex_lock(&dev->phy_mutex);
         asix_set_sw_mii(dev);
         asix_read_cmd(dev, AX_CMD_READ_MII_REG, phy_id,
                                 (__u16)loc, 2, (u16 *)&res);
         asix_set_hw_mii(dev);
+        mutex_unlock(&dev->phy_mutex);
 
         devdbg(dev, "asix_mdio_read() phy_id=0x%02x, loc=0x%02x, returns=0x%04x", phy_id, loc, le16_to_cpu(res & 0xffff));
 
@@ -586,10 +588,12 @@ asix_mdio_write(struct net_device *netdev, int phy_id, int loc, int val)
         u16 res = cpu_to_le16(val);
 
         devdbg(dev, "asix_mdio_write() phy_id=0x%02x, loc=0x%02x, val=0x%04x", phy_id, loc, val);
+        mutex_lock(&dev->phy_mutex);
         asix_set_sw_mii(dev);
         asix_write_cmd(dev, AX_CMD_WRITE_MII_REG, phy_id,
                                 (__u16)loc, 2, (u16 *)&res);
         asix_set_hw_mii(dev);
+        mutex_unlock(&dev->phy_mutex);
 }
 
 /* Get the PHY Identifier from the PHYSID1 & PHYSID2 MII registers */
diff --git a/drivers/usb/net/mcs7830.c b/drivers/usb/net/mcs7830.c
index 23a80667f17e..6240b978fe3d 100644
--- a/drivers/usb/net/mcs7830.c
+++ b/drivers/usb/net/mcs7830.c
@@ -184,6 +184,7 @@ static int mcs7830_read_phy(struct usbnet *dev, u8 index)
                 HIF_REG_PHY_CMD2_PEND_FLAG_BIT | index,
         };
 
+        mutex_lock(&dev->phy_mutex);
         /* write the MII command */
         ret = mcs7830_set_reg(dev, HIF_REG_PHY_CMD1, 2, cmd);
         if (ret < 0)
@@ -208,6 +209,7 @@ static int mcs7830_read_phy(struct usbnet *dev, u8 index)
         dev_dbg(&dev->udev->dev, "read PHY reg %02x: %04x (%d tries)\n",
                 index, val, i);
 out:
+        mutex_unlock(&dev->phy_mutex);
         return ret;
 }
 
@@ -222,6 +224,8 @@ static int mcs7830_write_phy(struct usbnet *dev, u8 index, u16 val)
                 HIF_REG_PHY_CMD2_PEND_FLAG_BIT | (index & 0x1F),
         };
 
+        mutex_lock(&dev->phy_mutex);
+
         /* write the new register contents */
         le_val = cpu_to_le16(val);
         ret = mcs7830_set_reg(dev, HIF_REG_PHY_DATA, 2, &le_val);
@@ -248,6 +252,7 @@ static int mcs7830_write_phy(struct usbnet *dev, u8 index, u16 val)
         dev_dbg(&dev->udev->dev, "write PHY reg %02x: %04x (%d tries)\n",
                 index, val, i);
 out:
+        mutex_unlock(&dev->phy_mutex);
         return ret;
 }
 
diff --git a/drivers/usb/net/usbnet.c b/drivers/usb/net/usbnet.c
index decc1b179246..cf3d20eb781c 100644
--- a/drivers/usb/net/usbnet.c
+++ b/drivers/usb/net/usbnet.c
@@ -1144,6 +1144,7 @@ usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod)
         dev->delay.function = usbnet_bh;
         dev->delay.data = (unsigned long) dev;
         init_timer (&dev->delay);
+        mutex_init (&dev->phy_mutex);
 
         SET_MODULE_OWNER (net);
         dev->net = net;
diff --git a/drivers/usb/net/usbnet.h b/drivers/usb/net/usbnet.h
index 743947c3fb83..07c70abbe0ec 100644
--- a/drivers/usb/net/usbnet.h
+++ b/drivers/usb/net/usbnet.h
@@ -30,6 +30,7 @@ struct usbnet {
         struct usb_device       *udev;
         struct driver_info      *driver_info;
         wait_queue_head_t       *wait;
+        struct mutex            phy_mutex;
 
         /* i/o info: pipes etc */
         unsigned                in, out;