22 Nov 2015 fzort   » (Journeyer)

Xperia E1 kernel tweaking (5)

Aaaand... another bug!

<4>[ 0.217984] WARNING: at /home/fzort/projects/xperia/kernel/fs/sysfs/dir.c:508 sysfs_add_one+0x88/0xb8()
<4>[ 0.218192] sysfs: cannot create duplicate filename '/class/sensors'

The device class sensors is registered twice, once by drivers/input/sensor_mgr.c, and then by (mainline kernel) drivers/sensors/sensors_class.c, which fails.

sensor_mgr.c seems to run first (is this deterministic?) so it's probably safe to remove sensors_class.c from the build. By the way, sensor_mgr.c also registers a device attribute called deviceInfor (yuck, camel case). Trying to read it on sysfs causes a kernel crash!

This bug is also present in stock software.

Edit: easy fix for the double /sys/class/sensors registration.

Edit 2: pretty awful kernel crash when doing a cat /sys/class/sensors/light/deviceInfor (or anything under /sys/class/sensors):

<1>[ 2909.524014] Unable to handle kernel NULL pointer dereference at virtual address 00000010
<1>[ 2909.524347] pgd = d4760000
<1>[ 2909.524610] [00000010] *pgd=00000000
<0>[ 2909.525297] Internal error: Oops: 805 [#1] PREEMPT SMP ARM

Edit 3: fixed

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