From: Russell King (Oracle) rmk+kernel@armlinux.org.uk
[ Upstream commit f4b47a2e9463950df3e7c8b70e017877c1d4eb11 ]
The locking in phy_probe() and phy_remove() does very little to prevent any races with e.g. phy_attach_direct(), but instead causes lockdep ABBA warnings. Remove it.
====================================================== WARNING: possible circular locking dependency detected 6.2.0-dirty #1108 Tainted: G W E ------------------------------------------------------ ip/415 is trying to acquire lock: ffff5c268f81ef50 (&dev->lock){+.+.}-{3:3}, at: phy_attach_direct+0x17c/0x3a0 [libphy]
but task is already holding lock: ffffaef6496cb518 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x154/0x560
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (rtnl_mutex){+.+.}-{3:3}: __lock_acquire+0x35c/0x6c0 lock_acquire.part.0+0xcc/0x220 lock_acquire+0x68/0x84 __mutex_lock+0x8c/0x414 mutex_lock_nested+0x34/0x40 rtnl_lock+0x24/0x30 sfp_bus_add_upstream+0x34/0x150 phy_sfp_probe+0x4c/0x94 [libphy] mv3310_probe+0x148/0x184 [marvell10g] phy_probe+0x8c/0x200 [libphy] call_driver_probe+0xbc/0x15c really_probe+0xc0/0x320 __driver_probe_device+0x84/0x120 driver_probe_device+0x44/0x120 __device_attach_driver+0xc4/0x160 bus_for_each_drv+0x80/0xe0 __device_attach+0xb0/0x1f0 device_initial_probe+0x1c/0x2c bus_probe_device+0xa4/0xb0 device_add+0x360/0x53c phy_device_register+0x60/0xa4 [libphy] fwnode_mdiobus_phy_device_register+0xc0/0x190 [fwnode_mdio] fwnode_mdiobus_register_phy+0x160/0xd80 [fwnode_mdio] of_mdiobus_register+0x140/0x340 [of_mdio] orion_mdio_probe+0x298/0x3c0 [mvmdio] platform_probe+0x70/0xe0 call_driver_probe+0x34/0x15c really_probe+0xc0/0x320 __driver_probe_device+0x84/0x120 driver_probe_device+0x44/0x120 __driver_attach+0x104/0x210 bus_for_each_dev+0x78/0xdc driver_attach+0x2c/0x3c bus_add_driver+0x184/0x240 driver_register+0x80/0x13c __platform_driver_register+0x30/0x3c xt_compat_calc_jump+0x28/0xa4 [x_tables] do_one_initcall+0x50/0x1b0 do_init_module+0x50/0x1fc load_module+0x684/0x744 __do_sys_finit_module+0xc4/0x140 __arm64_sys_finit_module+0x28/0x34 invoke_syscall+0x50/0x120 el0_svc_common.constprop.0+0x6c/0x1b0 do_el0_svc+0x34/0x44 el0_svc+0x48/0xf0 el0t_64_sync_handler+0xb8/0xc0 el0t_64_sync+0x1a0/0x1a4
-> #0 (&dev->lock){+.+.}-{3:3}: check_prev_add+0xb4/0xc80 validate_chain+0x414/0x47c __lock_acquire+0x35c/0x6c0 lock_acquire.part.0+0xcc/0x220 lock_acquire+0x68/0x84 __mutex_lock+0x8c/0x414 mutex_lock_nested+0x34/0x40 phy_attach_direct+0x17c/0x3a0 [libphy] phylink_fwnode_phy_connect.part.0+0x70/0xe4 [phylink] phylink_fwnode_phy_connect+0x48/0x60 [phylink] mvpp2_open+0xec/0x2e0 [mvpp2] __dev_open+0x104/0x214 __dev_change_flags+0x1d4/0x254 dev_change_flags+0x2c/0x7c do_setlink+0x254/0xa50 __rtnl_newlink+0x430/0x514 rtnl_newlink+0x58/0x8c rtnetlink_rcv_msg+0x17c/0x560 netlink_rcv_skb+0x64/0x150 rtnetlink_rcv+0x20/0x30 netlink_unicast+0x1d4/0x2b4 netlink_sendmsg+0x1a4/0x400 ____sys_sendmsg+0x228/0x290 ___sys_sendmsg+0x88/0xec __sys_sendmsg+0x70/0xd0 __arm64_sys_sendmsg+0x2c/0x40 invoke_syscall+0x50/0x120 el0_svc_common.constprop.0+0x6c/0x1b0 do_el0_svc+0x34/0x44 el0_svc+0x48/0xf0 el0t_64_sync_handler+0xb8/0xc0 el0t_64_sync+0x1a0/0x1a4
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1 ---- ---- lock(rtnl_mutex); lock(&dev->lock); lock(rtnl_mutex); lock(&dev->lock);
*** DEADLOCK ***
Fixes: 298e54fa810e ("net: phy: add core phylib sfp support") Reported-by: Marc Zyngier maz@kernel.org Signed-off-by: Russell King (Oracle) rmk+kernel@armlinux.org.uk Reviewed-by: Andrew Lunn andrew@lunn.ch Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/phy/phy_device.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-)
diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c index 3ef5aa6b72a7e..e771e0e8a9bc6 100644 --- a/drivers/net/phy/phy_device.c +++ b/drivers/net/phy/phy_device.c @@ -2833,8 +2833,6 @@ static int phy_probe(struct device *dev) if (phydrv->flags & PHY_IS_INTERNAL) phydev->is_internal = true;
- mutex_lock(&phydev->lock); - /* Deassert the reset signal */ phy_device_reset(phydev, 0);
@@ -2903,12 +2901,10 @@ static int phy_probe(struct device *dev) phydev->state = PHY_READY;
out: - /* Assert the reset signal */ + /* Re-assert the reset signal on error */ if (err) phy_device_reset(phydev, 1);
- mutex_unlock(&phydev->lock); - return err; }
@@ -2918,9 +2914,7 @@ static int phy_remove(struct device *dev)
cancel_delayed_work_sync(&phydev->state_queue);
- mutex_lock(&phydev->lock); phydev->state = PHY_DOWN; - mutex_unlock(&phydev->lock);
sfp_bus_del_upstream(phydev->sfp_bus); phydev->sfp_bus = NULL;