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    SubjectRe: [Letux-kernel] BUG: drivers/pinctrl/core: races in pinctrl_groups and deferred probing
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    Hi Tony,

    > Am 19.06.2018 um 08:11 schrieb Tony Lindgren <tony@atomide.com>:
    >
    > * H. Nikolaus Schaller <hns@goldelico.com> [180619 04:54]:
    >>>> I had seen the call sequence
    >>>>
    >>>>
    >>>>
    >>>> w/o any lock inside.
    >
    > So the sequence above has mutex added around adding the pin
    > controller specific functions and groups by the patch series
    > I posted for both pcs_parse_bits_in_pinctrl_entry() and
    > pcs_parse_one_pinctrl_entry(). So I think the above should
    > be fixed now. But please confirm to make sure I'm not mistaken.

    Ah, now I see.

    My dump_stack() added to pinctrl_generic_add_group() reported

    [ 6.155487] Hardware name: Generic OMAP36xx (Flattened Device Tree)
    [ 6.162048] [<c01106ec>] (unwind_backtrace) from [<c010c058>] (show_stack+0x10/0x14)
    [ 6.170166] [<c010c058>] (show_stack) from [<c074bc28>] (dump_stack+0x7c/0x9c)
    [ 6.177734] [<c074bc28>] (dump_stack) from [<c042bbec>] (pinctrl_generic_add_group+0x48/0x90)
    [ 6.186614] [<c042bbec>] (pinctrl_generic_add_group) from [<c043203c>] (pcs_dt_node_to_map+0x4b0/0x81c)
    [ 6.196441] [<c043203c>] (pcs_dt_node_to_map) from [<c042ffd4>] (pinctrl_dt_to_map+0x1ec/0x2b8)
    [ 6.205535] [<c042ffd4>] (pinctrl_dt_to_map) from [<c042d028>] (create_pinctrl+0x58/0x2f8)
    [ 6.214141] [<c042d028>] (create_pinctrl) from [<c042d388>] (devm_pinctrl_get+0x2c/0x6c)
    [ 6.222625] [<c042d388>] (devm_pinctrl_get) from [<c04f2e9c>] (pinctrl_bind_pins+0x3c/0x138)
    [ 6.231445] [<c04f2e9c>] (pinctrl_bind_pins) from [<c04d3eb8>] (driver_probe_device+0xe8/0x318)
    [ 6.240509] [<c04d3eb8>] (driver_probe_device) from [<c04d4168>] (__driver_attach+0x80/0xa4)
    [ 6.249328] [<c04d4168>] (__driver_attach) from [<c04d264c>] (bus_for_each_dev+0x58/0x7c)

    Apparently I didn't notice that pcs_parse_*_pinctrl_entry() are called
    inside pcs_dt_node_to_map() and are part of the call sequence.

    Hence your new mutex locks calls to pinctrl_generic_add_group() as
    needed.

    Obviously, the compiler has optimized away the nested calls to static
    functions and I had no previous experience with how the whole pinctrl code
    works (learning by debugging :).

    So it looks sane and no need for further locks.

    BR and thanks,
    Nikolaus

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