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Commit 9a6f2b01 authored by Andrew Lunn's avatar Andrew Lunn Committed by David S. Miller
Browse files

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: default avatarAndrew Lunn <andrew@lunn.ch>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 7c3da7d0

drivers/net/phy/mdio-mux.c

+2 −8
Original line number Diff line number Diff line
@@ -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;

drivers/net/phy/mdio_bus.c

+2 −2
Original line number Diff line number Diff line
@@ -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);

include/linux/mdio.h

+11 −0
Original line number Diff line number Diff line
@@ -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;