From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Armstrong Subject: [PATCH] net: dsa: mv88e6060: Fix false positive lockdep splat Date: Wed, 21 Oct 2015 17:37:45 +0200 Message-ID: <5627B149.6030109@baylibre.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit To: "David S. Miller" , Florian Fainelli , Guenter Roeck , vivien.didelot@savoirfairelinux.com, Andrew Lunn , Fabian Frederick , Pavel Nakonechny , Joe Perches , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, nbd@openwrt.org, sergei.shtylyov@cogentembedded.com Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org 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 --- drivers/net/dsa/mv88e6060.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) 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) \ -- 1.9.1