Re: WARNING from tty driver in 3.9-rc0

[Larry Finger <Larry.Finger@lwfinger.net>]

On 02/27/2013 03:19 PM, Jiri Slaby wrote:
> On 02/26/2013 10:56 PM, Daniel Mack wrote:
>> On Tue, Feb 26, 2013 at 10:25 PM, Larry Finger
>> <Larry.Finger@lwfinger.net> wrote:
>>> Hi,
>>>
>>> With v3.8-8693-gbf722a0 from the mainline repo, I get the following warning
>>> because the pointer for tty is NULL:
>>>
>>> [   34.956862] WARNING: at drivers/tty/tty_buffer.c:428
>>> flush_to_ldisc+0x1bb/0x1c0()
>>> [   34.956865] Hardware name: HP Pavilion dv2700 Notebook PC
>>> [   34.956867] tty is NULL
>>> [   34.956869] Modules linked in: arc4 b43 mac80211 cfg80211
>>> snd_hda_codec_conexant snd_hda_intel rfkill snd_hda_codec ipv6 snd_pcm
>>> kvm_amd snd_seq kvm bcma rng_core snd_timer snd_seq_device ssb mmc_core snd
>>> pcmcia sr_mod cdrom sg soundcore forcedeth pcmcia_core snd_page_alloc
>>> i2c_nforce2 i2c_core k8temp hwmon ehci_pci battery ac serio_raw joydev video
>>> wmi button autofs4 ext4 mbcache jbd2 crc16 ohci_hcd ehci_hcd usbcore
>>> usb_common thermal processor scsi_dh_alua scsi_dh_hp_sw scsi_dh_rdac
>>> scsi_dh_emc scsi_dh ata_generic pata_acpi pata_amd
>>> [   34.956936] Pid: 270, comm: kworker/1:1 Not tainted 3.8.0+ #92
>>> [   34.956939] Call Trace:
>>> [   34.956944]  [<ffffffff812acc00>] ? flush_to_ldisc+0x120/0x1c0
>>> [   34.956951]  [<ffffffff81040a4a>] warn_slowpath_common+0x7a/0xc0
>>> [   34.956955]  [<ffffffff81040b31>] warn_slowpath_fmt+0x41/0x50
>>> [   34.956959]  [<ffffffff812acc9b>] flush_to_ldisc+0x1bb/0x1c0
>>> [   34.956964]  [<ffffffff810640f1>] process_one_work+0x1f1/0x660
>>> [   34.956968]  [<ffffffff81064085>] ? process_one_work+0x185/0x660
>>> [   34.956972]  [<ffffffff81064900>] worker_thread+0x110/0x380
>>> [   34.956978]  [<ffffffff810a5b7d>] ? trace_hardirqs_on+0xd/0x10
>>> [   34.956982]  [<ffffffff810647f0>] ? rescuer_thread+0x250/0x250
>>> [   34.956987]  [<ffffffff81069e96>] kthread+0xd6/0xe0
>>> [   34.956992]  [<ffffffff81424c9b>] ? _raw_spin_unlock_irq+0x2b/0x50
>>> [   34.956997]  [<ffffffff81069dc0>] ? __init_kthread_worker+0x70/0x70
>>> [   34.957002]  [<ffffffff81425a7c>] ret_from_fork+0x7c/0xb0
>>> [   34.957006]  [<ffffffff81069dc0>] ? __init_kthread_worker+0x70/0x70
>>> [   34.957009] ---[ end trace f467d4f2302660c1 ]---
>>> [   35.585060] forcedeth 0000:00:0a.0: irq 42 for MSI/MSI-X
>>> [   35.585182] forcedeth 0000:00:0a.0 eth0: MSI enabled
>>> [   36.140711] ------------[ cut here ]------------
>>>
>>>
>>> I have not yet bisected this problem yet; however, I can if requested. Being
>>> lazy, I hope that someone already has a patch, or can see the problem by
>>> inspection. :)
>>
>> FWIW, I see the same on an ARM embedded board ...
>
> This one should be solved by Peter's "ldisc patchset". It didn't make it
> to 3.9 though. Anyway, the warning was added for debugging purposes only
> and it's apparently time to disable it now.

Jiri,

Thanks for looking into this. Will you be pushing a 3.9 patch to disable the 
warning?

Larry