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    SubjectRe: [PATCH] clk: Mark fwnodes when their clock provider is added
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    Hi

    On 10.02.2021 12:44, Tudor Ambarus wrote:
    > This is a follow-up for:
    > commit 3c9ea42802a1 ("clk: Mark fwnodes when their clock provider is added/removed")
    >
    > The above commit updated the deprecated of_clk_add_provider(),
    > but missed to update the preferred of_clk_add_hw_provider().
    > Update it now.
    >
    > Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>

    This patch, which landed in linux-next as commit 6579c8d97ad7 ("clk:
    Mark fwnodes when their clock provider is added") causes the following
    NULL pointer dereference on Raspberry Pi 3b+ boards:

    --->8---

    raspberrypi-firmware soc:firmware: Attached to firmware from
    2020-01-06T13:05:25
    Unable to handle kernel NULL pointer dereference at virtual address
    0000000000000050
    Mem abort info:
      ESR = 0x96000004
      EC = 0x25: DABT (current EL), IL = 32 bits
      SET = 0, FnV = 0
      EA = 0, S1PTW = 0
    Data abort info:
      ISV = 0, ISS = 0x00000004
      CM = 0, WnR = 0
    [0000000000000050] user address but active_mm is swapper
    Internal error: Oops: 96000004 [#1] PREEMPT SMP
    Modules linked in:
    CPU: 0 PID: 10 Comm: kworker/0:1 Not tainted 5.12.0-rc4+ #2764
    Hardware name: Raspberry Pi 3 Model B (DT)
    Workqueue: events deferred_probe_work_func
    pstate: 00000005 (nzcv daif -PAN -UAO -TCO BTYPE=--)
    pc : of_clk_add_hw_provider+0xac/0xe8
    lr : of_clk_add_hw_provider+0x94/0xe8
    sp : ffff8000130936b0
    x29: ffff8000130936b0 x28: ffff800012494e04
    x27: ffff00003b18cb05 x26: ffff00003aa5c010
    x25: 0000000000000000 x24: 0000000000000000
    x23: ffff00003aa1e380 x22: ffff8000106830d0
    x21: ffff80001233f180 x20: 0000000000000018
    x19: 0000000000000000 x18: ffff8000124d38b0
    x17: 0000000000000013 x16: 0000000000000014
    x15: ffff8000125758b0 x14: 00000000000184e0
    x13: 000000000000292e x12: ffff80001258dd98
    x11: 0000000000000001 x10: 0101010101010101
    x9 : ffff80001233f288 x8 : 7f7f7f7f7f7f7f7f
    x7 : fefefefeff6c626f x6 : 5d636d8080808080
    x5 : 00000000006d635d x4 : 0000000000000000
    x3 : 0000000000000000 x2 : 540eb5edae191600
    x1 : 0000000000000000 x0 : 0000000000000000
    Call trace:
     of_clk_add_hw_provider+0xac/0xe8
     devm_of_clk_add_hw_provider+0x5c/0xb8
     raspberrypi_clk_probe+0x110/0x210
     platform_probe+0x90/0xd8
     really_probe+0x108/0x3c0
     driver_probe_device+0x60/0xc0
     __device_attach_driver+0x9c/0xd0
     bus_for_each_drv+0x70/0xc8
     __device_attach+0xec/0x150
     device_initial_probe+0x10/0x18
     bus_probe_device+0x94/0xa0
     device_add+0x47c/0x780
     platform_device_add+0x110/0x248
     platform_device_register_full+0x120/0x150
     rpi_firmware_probe+0x158/0x1f8
     platform_probe+0x90/0xd8
     really_probe+0x108/0x3c0
     driver_probe_device+0x60/0xc0
     __device_attach_driver+0x9c/0xd0
     bus_for_each_drv+0x70/0xc8
     __device_attach+0xec/0x150
     device_initial_probe+0x10/0x18
     bus_probe_device+0x94/0xa0
     deferred_probe_work_func+0x70/0xa8
     process_one_work+0x2a8/0x718
     worker_thread+0x48/0x460
     kthread+0x134/0x160
     ret_from_fork+0x10/0x18
    Code: b1006294 540000c0 b140069f 54000088 (3940e280)
    ---[ end trace 7ead5ec2f0c51cfe ]---

    This patch mainly revealed that clk/bcm/clk-raspberrypi.c driver calls
    devm_of_clk_add_hw_provider(), with a device pointer, which has a NULL
    dev->of_node. I'm not sure if adding a check for a NULL np in
    of_clk_add_hw_provider() is a right fix, though.

    > ---
    > drivers/clk/clk.c | 2 ++
    > 1 file changed, 2 insertions(+)
    >
    > diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
    > index 27ff90eacb1f..9370e4dfecae 100644
    > --- a/drivers/clk/clk.c
    > +++ b/drivers/clk/clk.c
    > @@ -4594,6 +4594,8 @@ int of_clk_add_hw_provider(struct device_node *np,
    > if (ret < 0)
    > of_clk_del_provider(np);
    >
    > + fwnode_dev_initialized(&np->fwnode, true);
    > +
    > return ret;
    > }
    > EXPORT_SYMBOL_GPL(of_clk_add_hw_provider);

    Best regards
    --
    Marek Szyprowski, PhD
    Samsung R&D Institute Poland

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