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    SubjectRe: [PATCH] software node: balance refcount for managed sw nodes
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    Didn't notice in the first place, sorry about that. I now get this:

    sysfs: cannot create duplicate filename
    '/devices/platform/808622B7:00/xhci-hcd.1.auto/software_node'
    CPU: 3 PID: 1 Comm: swapper/0 Not tainted
    5.13.0-next-20210701-g5859a372a858-dirty #62
    Hardware name: NXP NXP LX2160ARDB Platform, BIOS EDK II Apr 16 2021
    Call trace:
    dump_backtrace+0x0/0x1c0
    show_stack+0x18/0x28
    dump_stack_lvl+0x68/0x84
    dump_stack+0x18/0x34
    sysfs_warn_dup+0x60/0x80
    sysfs_do_create_link_sd.isra.2+0x104/0x108
    sysfs_create_link+0x24/0x48
    software_node_notify+0xf0/0x148
    device_create_managed_software_node+0x90/0xc8
    iort_named_component_init+0x90/0xd0
    iort_iommu_configure_id+0x94/0x190
    acpi_dma_configure_id+0xc8/0x140
    platform_dma_configure+0x94/0xb0
    really_probe+0x70/0x2f8
    __driver_probe_device+0x7c/0xe8
    driver_probe_device+0x8c/0x130
    __driver_attach+0x98/0xf8
    bus_for_each_dev+0x7c/0xd8
    driver_attach+0x24/0x30
    bus_add_driver+0x154/0x200
    driver_register+0x64/0x120
    __platform_driver_register+0x28/0x38
    xhci_plat_init+0x30/0x3c
    do_one_initcall+0x60/0x1d8
    kernel_init_freeable+0x238/0x2ac
    kernel_init+0x24/0x128
    ret_from_fork+0x10/0x18

    ---
    Best Regards, Laurentiu

    On 7/16/2021 1:16 PM, laurentiu.tudor@nxp.com wrote:
    > From: Laurentiu Tudor <laurentiu.tudor@nxp.com>
    >
    > software_node_notify(), on KOBJ_REMOVE drops the refcount twice on managed
    > software nodes, thus leading to underflow errors. Balance the refcount by
    > bumping it in the device_create_managed_software_node() function.
    >
    > The error [1] was encountered after adding a .shutdown() op to our
    > fsl-mc-bus driver.
    >
    > [1]
    > pc : refcount_warn_saturate+0xf8/0x150
    > lr : refcount_warn_saturate+0xf8/0x150
    > sp : ffff80001009b920
    > x29: ffff80001009b920 x28: ffff1a2420318000 x27: 0000000000000000
    > x26: ffffccac15e7a038 x25: 0000000000000008 x24: ffffccac168e0030
    > x23: ffff1a2428a82000 x22: 0000000000080000 x21: ffff1a24287b5000
    > x20: 0000000000000001 x19: ffff1a24261f4400 x18: ffffffffffffffff
    > x17: 6f72645f726f7272 x16: 0000000000000000 x15: ffff80009009b607
    > x14: 0000000000000000 x13: ffffccac16602670 x12: 0000000000000a17
    > x11: 000000000000035d x10: ffffccac16602670 x9 : ffffccac16602670
    > x8 : 00000000ffffefff x7 : ffffccac1665a670 x6 : ffffccac1665a670
    > x5 : 0000000000000000 x4 : 0000000000000000 x3 : 00000000ffffffff
    > x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff1a2420318000
    > Call trace:
    > refcount_warn_saturate+0xf8/0x150
    > kobject_put+0x10c/0x120
    > software_node_notify+0xd8/0x140
    > device_platform_notify+0x4c/0xb4
    > device_del+0x188/0x424
    > fsl_mc_device_remove+0x2c/0x4c
    > rebofind sp.c__fsl_mc_device_remove+0x14/0x2c
    > device_for_each_child+0x5c/0xac
    > dprc_remove+0x9c/0xc0
    > fsl_mc_driver_remove+0x28/0x64
    > __device_release_driver+0x188/0x22c
    > device_release_driver+0x30/0x50
    > bus_remove_device+0x128/0x134
    > device_del+0x16c/0x424
    > fsl_mc_bus_remove+0x8c/0x114
    > fsl_mc_bus_shutdown+0x14/0x20
    > platform_shutdown+0x28/0x40
    > device_shutdown+0x15c/0x330
    > __do_sys_reboot+0x218/0x2a0
    > __arm64_sys_reboot+0x28/0x34
    > invoke_syscall+0x48/0x114
    > el0_svc_common+0x40/0xdc
    > do_el0_svc+0x2c/0x94
    > el0_svc+0x2c/0x54
    > el0t_64_sync_handler+0xa8/0x12c
    > el0t_64_sync+0x198/0x19c
    > ---[ end trace 32eb1c71c7d86821 ]---
    >
    > Reported-by: Jon Nettleton <jon@solid-run.com>
    > Suggested-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
    > Signed-off-by: Laurentiu Tudor <laurentiu.tudor@nxp.com>
    > ---
    > Changes since RFC:
    > - use software_node_notify(KOBJ_ADD) instead of directly bumping
    > refcount (Heikki)
    >
    > drivers/base/swnode.c | 3 +++
    > 1 file changed, 3 insertions(+)
    >
    > diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c
    > index d1f1a8240120..bdb50a06c82a 100644
    > --- a/drivers/base/swnode.c
    > +++ b/drivers/base/swnode.c
    > @@ -1113,6 +1113,9 @@ int device_create_managed_software_node(struct device *dev,
    > to_swnode(fwnode)->managed = true;
    > set_secondary_fwnode(dev, fwnode);
    >
    > + if (device_is_registered(dev))
    > + software_node_notify(dev, KOBJ_ADD);
    > +
    > return 0;
    > }
    > EXPORT_SYMBOL_GPL(device_create_managed_software_node);
    >

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