Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[~andy/linux] / drivers / net / phy / mdio-mux.c

diff --git a/drivers/net/phy/mdio-mux.c b/drivers/net/phy/mdio-mux.c
index 39ea0674dcde8cde6b31d71202b9b81873897ba6..5c120189ec86d419866b7320c36f4d618dc5df64 100644 (file)
--- a/drivers/net/phy/mdio-mux.c
+++ b/drivers/net/phy/mdio-mux.c
@@ -46,7 +46,13 @@ static int mdio_mux_read(struct mii_bus *bus, int phy_id, int regnum)
        struct mdio_mux_parent_bus *pb = cb->parent;
        int r;
 
-       mutex_lock(&pb->mii_bus->mdio_lock);
+       /* In theory multiple mdio_mux could be stacked, thus creating
+        * more than a single level of nesting.  But in practice,
+        * SINGLE_DEPTH_NESTING will cover the vast majority of use
+        * cases.  We use it, instead of trying to handle the general
+        * case.
+        */
+       mutex_lock_nested(&pb->mii_bus->mdio_lock, SINGLE_DEPTH_NESTING);
        r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
        if (r)
                goto out;
@@ -71,7 +77,7 @@ static int mdio_mux_write(struct mii_bus *bus, int phy_id,
 
        int r;
 
-       mutex_lock(&pb->mii_bus->mdio_lock);
+       mutex_lock_nested(&pb->mii_bus->mdio_lock, SINGLE_DEPTH_NESTING);
        r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
        if (r)
                goto out;