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Aleksei Sviridkin says: ==================== net: dsa: mt7530: fix two crashes on driver unbind Unbinding the MT7530 driver from an MT7531 dereferences NULL in regulator_disable(). On a Netcraze NC-1012 (MT7981B + MT7531, 6.18.44): # echo mdio-bus:1f > /sys/bus/mdio_bus/drivers/mt7530-mdio/unbind oopses there, and the build it was found on sets CONFIG_PANIC_ON_OOPS, so the board goes down with it. Fix that and the same command gets as far as mt7530_remove_common(), which disposes interrupt mappings the switch's own regmap-irq chip still owns; the regmap-irq thread then faults in handle_nested_irq() later in the same teardown. rmmod reaches both, since mdio_module_driver() calls .remove on module exit. Patch 1 is the regulator one. mt7530_probe() requests the core and io supplies only for ID_MT7530 and mt7530_setup() enables them under the same test, but mt7530_remove() disables them unconditionally, so on an MT7621 or an MT7531 both pointers are still NULL from devm_kzalloc(). It reaches the MDIO front end only. Patch 2 is the interrupt one, and it reaches further. mt7530_remove_common() disposes the per-PHY interrupt mappings by hand from .remove, while the regmap-irq chip that owns the domain is devm-registered and its parent interrupt is only freed once .remove has returned. regmap_del_irq_chip() disposes the same mappings itself, in an order that cannot race, so the driver's call adds nothing but a window. That helper is called from both front ends, so the defect also covers the MMIO parts - MT7988, EN7581, AN7583 and EN7528 - which have no regulators and never meet the first defect at all. The order is not arbitrary. On an MT7531 the regulator fault happens in the first thing mt7530_remove() does with the switch, so execution never reaches the interrupt defect. The second only became visible once the first was fixed, which is also how both came to be found on one board. Found and verified there. Without patch 1 the unbind panics in regulator_disable(); with patch 1 alone the panic moves on to handle_nested_irq(); with both, three unbind/bind cycles run, two back to back and a third after a pause. In the two whose dmesg was captured, each unbind removes the switch from the driver directory and takes lan1 to lan4 with it, each bind brings them back, and lan1 relinks at 1Gbps/full after both binds, lan4 after the second. uptime rose from 58 to 202 seconds across the three without resetting and pstore gained no new record. The third cycle stayed unbound long enough to read the descriptors: no mt7530 line in /proc/interrupts and no irq/79, irq/80 or irq/81 directory, and the next bind reuses those three numbers - regmap-irq freeing and disposing what the driver no longer touches. The kernel under test was identified by the sha256 of its ELF notes section, read from /sys/kernel/notes on the running board and computed in advance from the flashed image. What hardware could not answer here. There is no MT7530 or MT7621 part on this bench, so the ID_MT7530 branch that patch 1 adds was checked by reading the generated code rather than by running it, and no MMIO part was available to exercise patch 2 on that front end either. One unrelated WARN remains across the unbind, from sysfs_remove_link() under dsa_user_destroy(); it is a separate DSA teardown-ordering defect and is not addressed here. v1: https://lore.kernel.org/20260914202421.2737079-1-f@lex.la ==================== Link: https://patch.msgid.link/20260918015020.2518315-1-f@lex.la Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
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Linux kernel ============ The Linux kernel is the core of any Linux operating system. It manages hardware, system resources, and provides the fundamental services for all other software. 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