• Hans de Goede's avatar
    extcon: arizona: Fix various races on driver unbind · e5b499f6
    Hans de Goede authored
    We must free/disable all interrupts and cancel all pending works
    before doing further cleanup.
    
    Before this commit arizona_extcon_remove() was doing several
    register writes to shut things down before disabling the IRQs
    and it was cancelling only 1 of the 3 different works used.
    
    Move all the register-writes shutting things down to after
    the disabling of the IRQs and add the 2 missing
    cancel_delayed_work_sync() calls.
    
    This fixes various possible races on driver unbind. One of which
    would always trigger on devices using the mic-clamp feature for
    jack detection. The ARIZONA_MICD_CLAMP_MODE_MASK update was
    done before disabling the IRQs, causing:
    1. arizona_jackdet() to run
    2. detect a jack being inserted (clamp disabled means jack inserted)
    3. call arizona_start_mic() which:
    3.1 Enables the MICVDD regulator
    3.2 takes a pm_runtime_reference
    
    And this was all happening after the ARIZONA_MICD_ENA bit clearing,
    which would undo 3.1 and 3.2 because the ARIZONA_MICD_CLAMP_MODE_MASK
    update was being done after the ARIZONA_MICD_ENA bit clearing.
    
    So this means that arizona_extcon_remove() would exit with
    1. MICVDD enabled and 2. The pm_runtime_reference being unbalanced.
    
    MICVDD still being enabled caused the following oops when the
    regulator is released by the devm framework:
    
    [ 2850.745757] ------------[ cut here ]------------
    [ 2850.745827] WARNING: CPU: 2 PID: 2098 at drivers/regulator/core.c:2123 _regulator_put.part.0+0x19f/0x1b0
    [ 2850.745835] Modules linked in: extcon_arizona ...
    ...
    [ 2850.746909] Call Trace:
    [ 2850.746932]  regulator_put+0x2d/0x40
    [ 2850.746946]  release_nodes+0x22a/0x260
    [ 2850.746984]  __device_release_driver+0x190/0x240
    [ 2850.747002]  driver_detach+0xd4/0x120
    ...
    [ 2850.747337] ---[ end trace f455dfd7abd9781f ]---
    
    Note this oops is just one of various theoretically possible races caused
    by the wrong ordering inside arizona_extcon_remove(), this fixes the
    ordering fixing all possible races, including the reported oops.
    Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
    Reviewed-by: default avatarAndy Shevchenko <andy.shevchenko@gmail.com>
    Acked-by: default avatarCharles Keepax <ckeepax@opensource.cirrus.com>
    Tested-by: default avatarCharles Keepax <ckeepax@opensource.cirrus.com>
    Acked-by: default avatarChanwoo Choi <cw00.choi@samsung.com>
    Signed-off-by: default avatarLee Jones <lee.jones@linaro.org>
    e5b499f6
extcon-arizona.c 45.4 KB