f4b47a2e94
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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.