From 9a6f2b0113c8fce815db7c9d23754bdea4b428a0 Mon Sep 17 00:00:00 2001 From: Andrew Lunn Date: Mon, 11 Apr 2016 21:40:05 +0200 Subject: net: mdio: Fix lockdep falls positive splat MDIO devices can be stacked upon each other. The current code supports two levels, which until recently has been enough for a DSA mdio bus on top of another bus. Now we have hardware which has an MDIO mux in the middle. Define an MDIO MUTEX class with three levels. Signed-off-by: Andrew Lunn Signed-off-by: David S. Miller --- drivers/net/phy/mdio-mux.c | 10 ++-------- drivers/net/phy/mdio_bus.c | 4 ++-- include/linux/mdio.h | 11 +++++++++++ 3 files changed, 15 insertions(+), 10 deletions(-) diff --git a/drivers/net/phy/mdio-mux.c b/drivers/net/phy/mdio-mux.c index 308ade0..5c81d6f 100644 --- a/drivers/net/phy/mdio-mux.c +++ b/drivers/net/phy/mdio-mux.c @@ -45,13 +45,7 @@ static int mdio_mux_read(struct mii_bus *bus, int phy_id, int regnum) struct mdio_mux_parent_bus *pb = cb->parent; int r; - /* 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); + mutex_lock_nested(&pb->mii_bus->mdio_lock, MDIO_MUTEX_MUX); r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data); if (r) goto out; @@ -76,7 +70,7 @@ static int mdio_mux_write(struct mii_bus *bus, int phy_id, int r; - mutex_lock_nested(&pb->mii_bus->mdio_lock, SINGLE_DEPTH_NESTING); + mutex_lock_nested(&pb->mii_bus->mdio_lock, MDIO_MUTEX_MUX); r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data); if (r) goto out; diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c index 0cba64f..751202a 100644 --- a/drivers/net/phy/mdio_bus.c +++ b/drivers/net/phy/mdio_bus.c @@ -457,7 +457,7 @@ int mdiobus_read_nested(struct mii_bus *bus, int addr, u32 regnum) BUG_ON(in_interrupt()); - mutex_lock_nested(&bus->mdio_lock, SINGLE_DEPTH_NESTING); + mutex_lock_nested(&bus->mdio_lock, MDIO_MUTEX_NESTED); retval = bus->read(bus, addr, regnum); mutex_unlock(&bus->mdio_lock); @@ -509,7 +509,7 @@ int mdiobus_write_nested(struct mii_bus *bus, int addr, u32 regnum, u16 val) BUG_ON(in_interrupt()); - mutex_lock_nested(&bus->mdio_lock, SINGLE_DEPTH_NESTING); + mutex_lock_nested(&bus->mdio_lock, MDIO_MUTEX_NESTED); err = bus->write(bus, addr, regnum, val); mutex_unlock(&bus->mdio_lock); diff --git a/include/linux/mdio.h b/include/linux/mdio.h index 5bfd99d..bf9d1d7 100644 --- a/include/linux/mdio.h +++ b/include/linux/mdio.h @@ -13,6 +13,17 @@ struct mii_bus; +/* Multiple levels of nesting are possible. However typically this is + * limited to nested DSA like layer, a MUX layer, and the normal + * user. Instead of trying to handle the general case, just define + * these cases. + */ +enum mdio_mutex_lock_class { + MDIO_MUTEX_NORMAL, + MDIO_MUTEX_MUX, + MDIO_MUTEX_NESTED, +}; + struct mdio_device { struct device dev; -- cgit v1.1