[BUG] crash when removing sun4i_gpadc_iio module

[Corentin Labbe]

Hello

When inserting sun4i_gpadc_iio I got the following error in dmesg:
[79961.039826] thermal thermal_zone0: failed to read out thermal zone (-110)

Then removing the module cause an oops:
[80105.370937] Unable to handle kernel paging request at virtual address bf0ad1d0
[80105.370958] pgd = c0004000
[80105.370968] [bf0ad1d0] *pgd=6e470811, *pte=00000000, *ppte=00000000
[80105.371009] Internal error: Oops: 80000007 [#1] PREEMPT SMP ARM
[80105.376940] Modules linked in: algif_aead ccm gcm algif_rng crypto_user algif_skcipher algif_hash af_alg ghash_generic aes_arm_bs axp20x_ac_power axp20x_usb_power axp20x_adc gpio_axp209 nvmem_sunxi_sid sun4i_ss sun4i_dma virt_dma [last unloaded: sun4i_gpadc_iio]
[80105.400199] CPU: 0 PID: 14663 Comm: kworker/0:0 Tainted: G        W       4.11.0-rc8-next-20170428+ #96
[80105.409581] Hardware name: Allwinner sun7i (A20) Family
[80105.414821] Workqueue: events_freezable thermal_zone_device_check
[80105.420915] task: ee7d2880 task.stack: ea4fa000
[80105.425447] PC is at 0xbf0ad1d0
[80105.428594] LR is at arch_timer_read_counter_long+0x14/0x18
[80105.434166] pc : [<bf0ad1d0>]    lr : [<c010eab8>]    psr: 60070013
               sp : ea4fbea8  ip : ee7d2e00  fp : 00000001
[80105.445630] r10: ea4fbed4  r9 : 0000007b  r8 : 00000000
[80105.450852] r7 : ee7ffc14  r6 : ee7ff800  r5 : c09e2260  r4 : 0000005a
[80105.457373] r3 : c058e3d4  r2 : fac81000  r1 : 000001bf  r0 : 00005dbf
[80105.463897] Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
[80105.471025] Control: 10c5387d  Table: 66c9c06a  DAC: 00000051
[80105.476766] Process kworker/0:0 (pid: 14663, stack limit = 0xea4fa210)
[80105.483288] Stack: (0xea4fbea8 to 0xea4fc000)
[80105.487648] bea0:                   00000001 00000010 ee7ffbc0 ea4fbefc ef26dad4 ef7c2500
[80105.495821] bec0: ea4fbf28 00000000 00000000 bf0ad7e0 00000001 c070e80c c055d600 ef26d800
[80105.503994] bee0: ea4fbefc c055d614 00000000 ef26d800 ef7bef00 c055b040 ea4fbf28 ef26db20
[80105.512167] bf00: ef26db20 edf65680 ef7bef00 c013b374 00000001 00000000 c013b304 c013b798
[80105.520340] bf20: 00000000 00000000 c12624a4 c0dcdf20 00000000 c09c0e10 c0c04900 ef7bef00
[80105.528512] bf40: edf65698 00000008 c0c04900 ef7bef34 ea4fa000 ef7bef00 edf65680 c013b6f8
[80105.536685] bf60: ef7bf09c 00000000 edf65680 edf65380 00000000 e6c90700 edf65680 c013b6c0
[80105.544858] bf80: edf653b8 edf91e84 00000000 c01415c0 e6c90700 c0141484 00000000 00000000
[80105.553030] bfa0: 00000000 00000000 00000000 c01079b8 00000000 00000000 00000000 00000000
[80105.561202] bfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[80105.569374] bfe0: 00000000 00000000 00000000 00000000 00000013 00000000 6fffd861 6fffdc61
[80105.577558] [<c010eab8>] (arch_timer_read_counter_long) from [<00000010>] (0x10)
[80105.584952] Code: bad PC value
[80105.588283] ---[ end trace ff84d9d449c6a5b5 ]---

Regards
Corentin Labbe