| Message ID | 5627B149.6030109@baylibre.com |
|---|---|
| State | Superseded, archived |
| Delegated to: | David Miller |
| Headers | show |
On Wed, Oct 21, 2015 at 05:37:45PM +0200, Neil Armstrong wrote: > Like the change made for mv88e6xxx, use mutex_lock_nested() to avoid > lockdep to give false positives because of nested MDIO busses. Hi Neil We now have three instances of this, since mdio-mux.c has the same code. Maybe now would be a good time to refactor this code into mdiobus_read_nested() and mdiobus_write_nested() in mdio_bus.c? At the same time, add BUG_ON(in_interrupt()) similar to the non-nested versions? Andrew -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Andrew, On 10/21/2015 06:14 PM, Andrew Lunn wrote: > On Wed, Oct 21, 2015 at 05:37:45PM +0200, Neil Armstrong wrote: >> Like the change made for mv88e6xxx, use mutex_lock_nested() to avoid >> lockdep to give false positives because of nested MDIO busses. > > Hi Neil > > We now have three instances of this, since mdio-mux.c has the same > code. Maybe now would be a good time to refactor this code into > mdiobus_read_nested() and mdiobus_write_nested() in mdio_bus.c? At > the same time, add BUG_ON(in_interrupt()) similar to the non-nested > versions? > > Andrew > Indeed, you are right, I will post a serie with this refactoring. Neil -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 10/21/2015 06:14 PM, Andrew Lunn wrote: > On Wed, Oct 21, 2015 at 05:37:45PM +0200, Neil Armstrong wrote: >> Like the change made for mv88e6xxx, use mutex_lock_nested() to avoid >> lockdep to give false positives because of nested MDIO busses. > > Hi Neil > > We now have three instances of this, since mdio-mux.c has the same > code. Maybe now would be a good time to refactor this code into > mdiobus_read_nested() and mdiobus_write_nested() in mdio_bus.c? At > the same time, add BUG_ON(in_interrupt()) similar to the non-nested > versions? > > Andrew > Well, mdio-mux also calls switch_fn inside the mdio_lock, clean refactoring would introduce a separate lock and call the nested variants. Is that ok ? Can someone test mdio-mux is I make the change ? Neil -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 10/21/2015 06:14 PM, Andrew Lunn wrote: > On Wed, Oct 21, 2015 at 05:37:45PM +0200, Neil Armstrong wrote: >> Like the change made for mv88e6xxx, use mutex_lock_nested() to avoid >> lockdep to give false positives because of nested MDIO busses. > > Hi Neil > > We now have three instances of this, since mdio-mux.c has the same > code. Maybe now would be a good time to refactor this code into > mdiobus_read_nested() and mdiobus_write_nested() in mdio_bus.c? At > the same time, add BUG_ON(in_interrupt()) similar to the non-nested > versions? > > Andrew > Well, mdio-mux also calls switch_fn inside the mdio_lock, clean refactoring would introduce a separate lock and call the nested variants. Is that ok ? Can someone test mdio-mux if I make the change ? Neil -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
> Well, mdio-mux also calls switch_fn inside the mdio_lock, clean refactoring > would introduce a separate lock and call the nested variants. > Is that ok ? Can someone test mdio-mux if I make the change ? Hi Neil I would not touch mdio-mux. As you said, it does more than lock, read, unlock. It is not something sufficiently generic to place into shared code. Andrew -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/net/dsa/mv88e6060.c b/drivers/net/dsa/mv88e6060.c index c29aebe..b1db460 100644 --- a/drivers/net/dsa/mv88e6060.c +++ b/drivers/net/dsa/mv88e6060.c @@ -19,14 +19,24 @@ #define REG_PORT(p) (8 + (p)) #define REG_GLOBAL 0x0f +/* MDIO bus access can be nested in the case of PHYs connected to the + * internal MDIO bus of the switch, which is accessed via MDIO bus of + * the Ethernet interface. Avoid lockdep false positives by using + * mutex_lock_nested(). + */ static int reg_read(struct dsa_switch *ds, int addr, int reg) { + int ret; struct mii_bus *bus = dsa_host_dev_to_mii_bus(ds->master_dev); if (bus == NULL) return -EINVAL; - return mdiobus_read(bus, ds->pd->sw_addr + addr, reg); + mutex_lock_nested(&bus->mdio_lock, SINGLE_DEPTH_NESTING); + ret = bus->read(bus, ds->pd->sw_addr, reg); + mutex_unlock(&bus->mdio_lock); + + return ret; } #define REG_READ(addr, reg) \ @@ -42,12 +52,17 @@ static int reg_read(struct dsa_switch *ds, int addr, int reg) static int reg_write(struct dsa_switch *ds, int addr, int reg, u16 val) { + int ret; struct mii_bus *bus = dsa_host_dev_to_mii_bus(ds->master_dev); if (bus == NULL) return -EINVAL; - return mdiobus_write(bus, ds->pd->sw_addr + addr, reg, val); + mutex_lock_nested(&bus->mdio_lock, SINGLE_DEPTH_NESTING); + ret = bus->write(bus, ds->pd->sw_addr, reg, val); + mutex_unlock(&bus->mdio_lock); + + return ret; } #define REG_WRITE(addr, reg, val) \
Like the change made for mv88e6xxx, use mutex_lock_nested() to avoid lockdep to give false positives because of nested MDIO busses. The false positive was observed using a mv88e6060 from a TI816X SoC. Signed-off-by: Neil Armstrong <narmstrong@baylibre.com> --- drivers/net/dsa/mv88e6060.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-)