[MinnowBoard] LED: Kernel Dump

John 'Warthog9' Hawley warthog9 at eaglescrag.net
Sat Mar 14 22:06:42 UTC 2015


On 03/14/2015 11:45 AM, Abraham Arce wrote:
> Hi,
> 
> While working with Martin Oldfield's documentation
>  http://www.mjoldfield.com/atelier/2014/12/mbmx-leds.html
> I am having the below kernel dump when module seabass-leds is remove
>  https://github.com/mjoldfield/seabass/blob/master/seabass-leds/seabass-leds.c
> 
> [ 1552.096607] ------------[ cut here ]------------
> [ 1552.096623] WARNING: CPU: 0 PID: 16840 at drivers/base/core.c:250
> device_release+0x7b/0x87()
> [ 1552.096627] Device 'leds-gpio' does not have a release() function, it
> is broken and must be fixed.
> [ 1552.096633] Modules linked in: seabass_leds(O-) ledtrig_oneshot
> ledtrig_heartbeat leds_gpio bnep rfcomm bluetooth rfkill nfsd
> auth_rpcgss oid_registry nfs_acl nfs lockd grace fscache sunrpc nls_utf8
> nls_cp437 vfat fat loop coretemp iTCO_wdt kvm_intel iTCO_vendor_support
> kvm snd_hda_codec_hdmi snd_hda_intel snd_hda_controller
> ghash_clmulni_intel snd_hda_codec snd_hwdep snd_pcm snd_seq aesni_intel
> aes_x86_64 ablk_helper cryptd snd_timer lrw snd_seq_device gf128mul
> glue_helper microcode pcspkr efivars snd lpc_ich mfd_core i2c_i801
> joydev soundcore dw_dmac dw_dmac_core i2c_designware_platform
> spi_pxa2xx_platform i2c_designware_core processor evdev ext4 crc16 jbd2
> mbcache hid_generic usbhid hid crc32c_intel sd_mod thermal [last
> unloaded: seabass_leds]
> [ 1552.096736] CPU: 0 PID: 16840 Comm: rmmod Tainted: G        W  O   
> 4.0.0-rc3+ #4
> [ 1552.096741] Hardware name: Intel Corp. Minnowboard Max B3
> PLATFORM/NOTEBOOK, BIOS MNW2MAX1.X64.0073.R02.1409160934 09/16/2014
> [ 1552.096745]  0000000000000000 0000000000000009 ffffffff814dee1e
> ffff88005dbd3e78
> [ 1552.096753]  ffffffff8103e8bb ffffffffa03cb020 ffffffff8135741c
> 0000000000000000
> [ 1552.096760]  ffffffffa03cb020 ffffffffa03cb010 ffff880065d1c7c0
> 00007fff2607a826
> [ 1552.096767] Call Trace:
> [ 1552.096779]  [<ffffffff814dee1e>] ? dump_stack+0x40/0x50
> [ 1552.096788]  [<ffffffff8103e8bb>] ? warn_slowpath_common+0x98/0xb0
> [ 1552.096796]  [<ffffffff8135741c>] ? device_release+0x7b/0x87
> [ 1552.096804]  [<ffffffff8103e96b>] ? warn_slowpath_fmt+0x45/0x4a
> [ 1552.096812]  [<ffffffff8135741c>] ? device_release+0x7b/0x87
> [ 1552.096821]  [<ffffffff811df232>] ? kobject_cleanup+0x43/0x59
> [ 1552.096831]  [<ffffffffa03c901b>] ? seabass_exit+0x1b/0x1000
> [seabass_leds]
> [ 1552.096847]  [<ffffffffa03c9000>] ? 0xffffffffa03c9000
> [ 1552.096855]  [<ffffffff8109316e>] ? SyS_delete_module+0x12d/0x1a3
> [ 1552.096864]  [<ffffffff81002680>] ? do_notify_resume+0x3b/0x48
> [ 1552.096872]  [<ffffffff814e3fa9>] ? int_signal+0x12/0x17
> [ 1552.096880]  [<ffffffff814e3d72>] ? system_call_fastpath+0x12/0x17
> [ 1552.096885] ---[ end trace 6e432b721aa0aeb8 ]---
> [ 1552.096890] seabass: led exit
> [ 1578.843786] seabass: module init
> [ 1578.844231] seabass: led init stat = 0

Quick reading on the kernel dump you've posted shows we likely aren't
going to be able to do much to "fix" it.  Specifically it looks like the
LED-gpio subsystem doesn't really handle removes correctly:

	[ 1552.096627] Device 'leds-gpio' does not have a release()
		       function, it is broken and must be fixed.

I'd claim maybe it's fixed in a newer kernel, but you are running a
4.0.0-rc3 kernel, which it's hard to get much newer right now.  My only
suggestion would be to start looking at why leds-gpio doesn't have a
release() function.

- John 'Warthog9' Hawley


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