2.6.36-rc1: WARNING when loading ehci-hcd module

From: Nick Bowler
Date: Mon Aug 16 2010 - 14:45:22 EST


After installing 2.6.36-rc1, I found a call trace in my dmesg after
boot. Traking it down a bit, it appears to happen when ehci-hcd is
loaded. The log after running 'modprobe ehci-hcd' appended to this
mail. This wasn't a problem in 2.6.35, but I don't have time to bisect
right now.

Now, I see the warning about how ehci should be loaded before uhci. I
also see that this is apparently not a new message. My configuration
has uhci built-in but ehci as a module. If this is not a supported
configuration, probably some dependencies need to be fixed in the
Kconfig.

Other than the trace, there seems to be no problems related to ehci.

ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
Warning! ehci_hcd should always be loaded before uhci_hcd and ohci_hcd, not after
ehci_hcd 0000:00:1a.7: PCI INT C -> GSI 18 (level, low) -> IRQ 18
ehci_hcd 0000:00:1a.7: setting latency timer to 64
ehci_hcd 0000:00:1a.7: EHCI Host Controller
ehci_hcd 0000:00:1a.7: new USB bus registered, assigned bus number 7
ehci_hcd 0000:00:1a.7: debug port 1
ehci_hcd 0000:00:1a.7: cache line size of 32 is not supported
ehci_hcd 0000:00:1a.7: irq 18, io mem 0xfe9f8000
ehci_hcd 0000:00:1a.7: USB 2.0 started, EHCI 1.00
hub 7-0:1.0: USB hub found
hub 7-0:1.0: 6 ports detected
ehci_hcd 0000:00:1d.7: PCI INT A -> GSI 23 (level, low) -> IRQ 23
ehci_hcd 0000:00:1d.7: setting latency timer to 64
ehci_hcd 0000:00:1d.7: EHCI Host Controller
ehci_hcd 0000:00:1d.7: new USB bus registered, assigned bus number 8
ehci_hcd 0000:00:1d.7: debug port 1
ehci_hcd 0000:00:1d.7: cache line size of 32 is not supported
ehci_hcd 0000:00:1d.7: irq 23, io mem 0xfe9f2000
ehci_hcd 0000:00:1d.7: USB 2.0 started, EHCI 1.00
hub 8-0:1.0: USB hub found
hub 8-0:1.0: 6 ports detected
usb 2-1: USB disconnect, address 2
usb 2-2: USB disconnect, address 3
------------[ cut here ]------------
WARNING: at /scratch_space/linux-2.6/lib/kobject.c:595 kobject_put+0x2f/0x42()
Hardware name: Aspire X3810
kobject: '(null)' (ffff88013e02d898): is not initialized, yet kobject_put() is being called.
Modules linked in: ehci_hcd nfs nfs_acl bridge stp llc autofs4 nfsd lockd sunrpc exportfs ipv6 iptable_filter iptable_nat nf_nat nf_conntrack_ipv4 nf_conntrack nf_defrag_ipv4 ip_tables x_tables snd_seq_dummy snd_seq_oss snd_seq_midi_event snd_seq snd_seq_device snd_pcm_oss snd_mixer_oss snd_hda_codec_intelhdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_timer snd soundcore snd_page_alloc ext2 evdev sr_mod cdrom loop tun acpi_cpufreq mperf e1000e
Pid: 256, comm: khubd Not tainted 2.6.36-rc1-00001-g6041d49 #17
Call Trace:
[<ffffffff810329b8>] ? warn_slowpath_common+0x78/0x8c
[<ffffffff81032a6b>] ? warn_slowpath_fmt+0x45/0x4a
[<ffffffff812d389c>] ? notifier_call_chain+0x2e/0x5b
[<ffffffff81132a70>] ? kobject_put+0x2f/0x42
[<ffffffff8124e2a7>] ? usbhid_disconnect+0x2c/0x35
[<ffffffff81222147>] ? usb_unbind_interface+0x45/0xc3
[<ffffffff811f5e25>] ? __device_release_driver+0x65/0xb0
[<ffffffff811f5f24>] ? device_release_driver+0x11/0x1a
[<ffffffff811f532e>] ? bus_remove_device+0x9f/0xb4
[<ffffffff811f39e4>] ? device_del+0x120/0x16a
[<ffffffff812200e7>] ? usb_disable_device+0x6c/0xe0
[<ffffffff8121bdb8>] ? usb_disconnect+0x77/0x109
[<ffffffff8121c447>] ? hub_thread+0x428/0xd84
[<ffffffff8104772f>] ? autoremove_wake_function+0x0/0x2a
[<ffffffff8121c01f>] ? hub_thread+0x0/0xd84
[<ffffffff8121c01f>] ? hub_thread+0x0/0xd84
[<ffffffff8104733a>] ? kthread+0x7a/0x82
[<ffffffff81003654>] ? kernel_thread_helper+0x4/0x10
[<ffffffff810472c0>] ? kthread+0x0/0x82
[<ffffffff81003650>] ? kernel_thread_helper+0x0/0x10
---[ end trace 1f9da30167172bba ]---

--
Nick Bowler, Elliptic Technologies (http://www.elliptictech.com/)
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