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Date: Mon, 7 Feb 2022 18:15:49 +0200 From: Vladimir Oltean <vladimir.oltean@....com> To: netdev@...r.kernel.org Cc: Florian Fainelli <f.fainelli@...il.com>, Andrew Lunn <andrew@...n.ch>, Vivien Didelot <vivien.didelot@...il.com>, Vladimir Oltean <olteanv@...il.com>, "David S. Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, Hauke Mehrtens <hauke@...ke-m.de>, Sean Wang <sean.wang@...iatek.com>, Landen Chao <Landen.Chao@...iatek.com>, DENG Qingfang <dqfext@...il.com>, Matthias Brugger <matthias.bgg@...il.com>, Claudiu Manoil <claudiu.manoil@....com>, Alexandre Belloni <alexandre.belloni@...tlin.com>, UNGLinuxDriver@...rochip.com, Oleksij Rempel <linux@...pel-privat.de>, Bartosz Golaszewski <bgolaszewski@...libre.com>, Laurentiu Tudor <laurentiu.tudor@....com>, Rafael Richter <rafael.richter@....de>, Daniel Klauer <daniel.klauer@....de> Subject: [PATCH net 3/7] net: dsa: bcm_sf2: don't use devres for mdiobus As explained in commits: 74b6d7d13307 ("net: dsa: realtek: register the MDIO bus under devres") 5135e96a3dd2 ("net: dsa: don't allocate the slave_mii_bus using devres") mdiobus_free() will panic when called from devm_mdiobus_free() <- devres_release_all() <- __device_release_driver(), and that mdiobus was not previously unregistered. The Starfighter 2 is a platform device, so the initial set of constraints that I thought would cause this (I2C or SPI buses which call ->remove on ->shutdown) do not apply. But there is one more which applies here. If the DSA master itself is on a bus that calls ->remove from ->shutdown (like dpaa2-eth, which is on the fsl-mc bus), there is a device link between the switch and the DSA master, and device_links_unbind_consumers() will unbind the bcm_sf2 switch driver on shutdown. So the same treatment must be applied to all DSA switch drivers, which is: either use devres for both the mdiobus allocation and registration, or don't use devres at all. The bcm_sf2 driver has the code structure in place for orderly mdiobus removal, so just replace devm_mdiobus_alloc() with the non-devres variant, and add manual free where necessary, to ensure that we don't let devres free a still-registered bus. Fixes: ac3a68d56651 ("net: phy: don't abuse devres in devm_mdiobus_register()") Signed-off-by: Vladimir Oltean <vladimir.oltean@....com> --- drivers/net/dsa/bcm_sf2.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/net/dsa/bcm_sf2.c b/drivers/net/dsa/bcm_sf2.c index 9161ce4ca352..cf82b1fa9725 100644 --- a/drivers/net/dsa/bcm_sf2.c +++ b/drivers/net/dsa/bcm_sf2.c @@ -621,7 +621,7 @@ static int bcm_sf2_mdio_register(struct dsa_switch *ds) get_device(&priv->master_mii_bus->dev); priv->master_mii_dn = dn; - priv->slave_mii_bus = devm_mdiobus_alloc(ds->dev); + priv->slave_mii_bus = mdiobus_alloc(); if (!priv->slave_mii_bus) { of_node_put(dn); return -ENOMEM; @@ -681,8 +681,10 @@ static int bcm_sf2_mdio_register(struct dsa_switch *ds) } err = mdiobus_register(priv->slave_mii_bus); - if (err && dn) + if (err && dn) { + mdiobus_free(priv->slave_mii_bus); of_node_put(dn); + } return err; } @@ -690,6 +692,7 @@ static int bcm_sf2_mdio_register(struct dsa_switch *ds) static void bcm_sf2_mdio_unregister(struct bcm_sf2_priv *priv) { mdiobus_unregister(priv->slave_mii_bus); + mdiobus_free(priv->slave_mii_bus); of_node_put(priv->master_mii_dn); } -- 2.25.1
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